Chagas disease is a chronic, systemic, parasitic infection caused by the protozoan Trypanosoma cruzi, and was discovered in 1909. The disease affects about 8 million people in Latin America, of whom 30-40% either have or will develop cardiomyopathy, digestive megasyndromes, or both. In the past three decades, the control and management of Chagas disease has undergone several improvements. Large-scale vector control programmes and screening of blood donors have reduced disease incidence and prevalence. Although more effective trypanocidal drugs are needed, treatment with benznidazole (or nifurtimox) is reasonably safe and effective, and is now recommended for a widened range of patients. Improved models for risk stratification are available, and certain guided treatments could halt or reverse disease progression (Rassi et al., 2010).
4. Microbial Pathogenesis
Organ and tissue damage during acute T cruzi infection is caused by the parasite itself and by the host's acute immunoinflammatory response, which is elicited by the presence of the parasite. Findings from several studies in experimental models of T cruzi infection have suggested that a strong T-helper-1 immune response with both CD4 and CD8 cells, and characterised by the production of some specific cytokines—such as interferon γ, tumour necrosis factor α, and interleukin 12—is important in the control of parasitism. By comparison, production of interleukin 10 and transforming growth factor β is related to parasite replication by inhibition of macrophage trypanocidal activity. The T-helper-1 immune response has a protective role mainly through the synthesis of nitric oxide, which exerts a potent trypanocidal action. During chronic infection, the balance between immune-mediated parasite containment and damaging inflammation of the host tissues probably determines the course of disease. If the immunological response is inefficient, or paradoxically leads to tissue damage, both parasite load and immune-mediated inflammation increase. By contrast, a well executed immune response, in which parasite burden is lowered and inflammatory consequences are kept to a minimum, results in reduced tissue damage (Rassi et al., 2010).
5. Host Ranges and Animal Models
Chagas disease is transmitted to human beings and to more than 150 species of domestic animals (eg, dogs, cats, and guineapigs) and wild mammals (eg, rodents, marsupials, and armadillos) mainly by large, blood-sucking reduviid bugs of the subfamily Triatominae, within three overlapping cycles: domestic, peridomestic, and sylvatic. Although more than 130 species of triatomine bugs have been identified, only a handful are competent vectors for T cruzi. Triatoma infestans, Rhodnius prolixus, and Triatoma dimidiata are the three most important vector species in the transmission of T cruzi to man (Rassi et al., 2010).
Molecule Role Annotation :
To examine the efficacy of a new mode of recombinant viral vaccine, a vaccine was constructed of two non-transmissible Sendai viruses (rSeV/dF) encoding the full-length parasite antigen amastigote surface protein-2 (ASP2) or ASP2 fused with a mono-ubiquitin on its N-terminus (UASP2). C57BL/6 mice immunized intranasally with rSeV/dF expressing either ASP2 or UASP2 showed significantly suppressed parasitemia and could be protected from lethal T. cruzi challenge (Duan et al., 2009).
Molecule Role Annotation :
A complement regulatory protein (CRP) of Trypanosoma cruzi was evaluated as a vaccine candidate in a murine model of experimental T. cruzi infection. Recombinant CRP derived from an Escherichia coli expression system and a plasmid encoding the full-length crp structural gene under the control of a eukaryotic promoter were used to immunize BALB/c mice. Immunization with both protein and DNA vaccines resulted in a Th1-type T-cell response, comparable antibody titers, and similar immunoglobulin G isotype profiles. Only mice immunized with the crp DNA plasmid produced antibodies capable of lysing the parasites in the presence of complement and were protected against a lethal challenge with T. cruzi trypomastigotes (Sepulveda et al., 2000).
Molecule Role Annotation :
To study the protective effects in vivo of cruzipain-specific Th1 responses against systemic T. cruzi challenges, mice were immunized with recombinant cruzipain plus interleukin 12 (IL-12) and a neutralizing anti-IL-4 MAb. These immunized mice developed potent cruzipain-specific memory Th1 cell responses and were significantly protected against normally lethal systemic T. cruzi challenges. To study whether cruzipain could induce mucosal immune responses relevant for vaccine development, recombinant attenuated Salmonella enterica serovar Typhimurium vaccines expressing cruzipain were prepared. BALB/c mice immunized with salmonella expressing cruzipain were significantly protected against T. cruzi mucosal infection (Schnapp et al., 2002).
Molecule Role Annotation :
The vaccine efficacy of a putative candidate antigen against T. cruzi infection and disease in a mouse model. C57BL/6 mice vaccinated with a T. cruzi G2-encoding plasmid and cytokine (interleukin-12 and granulocyte-macrophage colony-stimulating factor) expression plasmids elicited a strong Th1-type antibody response dominated by immunoglobulin G2b (IgG2b)/IgG1 isotypes. The dominant IgG2b/IgG1 antibody response was maintained after a challenge infection and was associated with 50% control of the acute-phase tissue parasite burden and an almost undetectable level of tissue parasites during the chronic phase, as determined by a sensitive T. cruzi 18S rRNA gene-specific real-time PCR approach (Bhatia and Garg, 2008).
Molecule Role Annotation :
Female MyD88−/− mice on a C57BL/6 background were grown under specific pathogen-free conditions at the University of Michigan (Rudd et al., 2007).
Molecule Role Annotation :
C57BL/6 mice were immunized s.c. with recombinant PFR-1 (PAR1) protein co-adsorbed to alum with rIL-12. rPFR-1 immunized animals were able to successfully resolve parasitemia by day 30 p.i., with the peak parasitemia occurring between days 17 and 21 p.i. (Luhrs et al., 2003).
>AAU47268.1 protein G4 [Trypanosoma cruzi]
MSAKAPPKTLHQVRNVAYIFAAWAGLQKGFAEKSANDKMWVEHQRRLRQENAKRQHAAHALEELKQDEEL
ERSIPTIVPKELHELVKALEK
Molecule Role :
Protective antigen
Molecule Role Annotation :
The vaccine efficacy of a putative candidate antigen against T. cruzi infection and disease in a mouse model. C57BL/6 mice vaccinated with a T. cruzi G4-encoding plasmid and cytokine (interleukin-12 and granulocyte-macrophage colony-stimulating factor) expression plasmids elicited a strong Th1-type antibody response dominated by immunoglobulin G2b (IgG2b)/IgG1 isotypes. The dominant IgG2b/IgG1 antibody response was maintained after a challenge infection and was associated with 90% control of the acute-phase tissue parasite burden and an almost undetectable level of tissue parasites during the chronic phase, as determined by a sensitive T. cruzi 18S rRNA gene-specific real-time PCR approach (Bhatia and Garg, 2008).
>XP_802646.1 paraxonemal rod protein PAR2, partial [Trypanosoma cruzi strain CL Brener]
QDEAWRRIQELERVLQRLGTERFEEVKRRIEENDREEKRKVEYQQFLDVCGQHKKLLELSVYNCDLAMRC
IGMMEELVAEGCSAIKSRHDKTNEELGDLRLQVHQEYLEAFRRLYKTLGQLVYKKEKRLEEIDRNIRTTH
IQLEFAIETFDPNAKKHSDAKKELYKLRAQVEEELEMLKDKMAQALEMFGPTEDALNQAGIEFVHPAEEV
EDGNLTRRSKMVEYRAHLAKQEEVKIAAEREELKRSKTLQSQQYRGKTVQQITQ
Molecule Role :
Protective antigen
Molecule Role Annotation :
C57BL/6 mice were immunized s.c. with recombinant PFR-2 (PAR2) protein co-adsorbed to alum with rIL-12. rPFR-2 immunized animals were able to successfully resolve parasitemia by day 30 p.i., with the peak parasitemia occurring between days 17 and 21 p.i. (Luhrs et al., 2003).
Protein Note :
EF-hand, calcium binding motif; A diverse superfamily of calcium sensors and calcium signal modulators; most examples in this alignment model have 2 active canonical EF hands. Ca2+ binding induces a conformational change in the EF-hand motif, leading to...; cd00051
Protein Note :
EF-hand, calcium binding motif; A diverse superfamily of calcium sensors and calcium signal modulators; most examples in this alignment model have 2 active canonical EF hands. Ca2+ binding induces a conformational change in the EF-hand motif, leading to...; cd00051
Protein Note :
Glutathione S-transferase (GST) family, N-terminal domain; a large, diverse group of cytosolic dimeric proteins involved in cellular detoxification by catalyzing the conjugation of glutathione (GSH) with a wide range of endogenous and xenobiotic...; cd00570
Molecule Role Annotation :
To develop a vaccine strategy taking advantage of activated CD8(+)T cells,a DNA vaccine, designated pGFP-TSA1, encoding a fusion protein linking GFP to a single CTL epitope of TSA1(TS), a leading candidate for vaccine against T. cruzi was constructed. C57BL/6 mice vaccinated with this plasmid showed suppressed parasitemia and prolonged survival. Vaccination with pGFP-TSA1 enhanced epitope-specific cytotoxicity and IFN-gamma secretion by CD8(+)T cells (Chou et al., 2008).
Molecule Role Annotation :
Following the intramuscular immunization of H-2(b) and H-2(d) mice with a plasmid DNA encoding an N-terminally truncated TSA-1 lacking or containing the C-terminal nonapeptide tandem repeats, the antibody level, CTL response, and protection against challenge with T. cruzi were assessed. In H-2(b) mice, antiparasite antibodies were induced only by immunization with the DNA construct encoding TSA-1 containing the C-terminal repeats. However, both DNA constructs were efficient in eliciting long-lasting CTL responses against the protective H-2Kb-restricted TSA-1515-522 epitope. In H-2(d) mice, inoculation with either of the two TSA-1-expressing vectors effectively generated antiparasite antibodies and primed CTLs that lysed T. cruzi-infected cells in an antigen-specific, MHC class I-restricted, and CD8(+)-T-cell-dependent manner. When TSA-1 DNA-vaccinated animals were challenged with T. cruzi, 14 of 22 (64%) H-2(b) and 16 of 18 (89%) H-2(d) mice survived the infection (Wizel et al., 1998).
1. T. cruzi DNA prime/Protein-boost vaccine encoding TcG2 and TcG4
a. Type:
Prime-boost vaccine with DNA vaccine priming
b. Status:
Research
c. Host Species for Licensed Use:
None
d. Antigen
TcG2 and TcG4 (Gupta et al., 2015) - T. cruzi encoding plasmids which have elicited a strong Th1 - type antibody response dominated by immunoglobin G2b (IgG2b)/IgG1 isotypes. (Bhatia and Garg, 2008)
A DNA-prime/protein boost therapeutic vaccine encoding TcG2 and TcG4 aimed to determine if GPx1, an antioxidant, protects the heart form chagasic pathogenesis. (Gupta et al., 2015)
k.
Mouse Response
Host Strain:
C57BL/6
Vaccination Protocol:
Mice were infected with T. cruzi (10,000 trypomastigotes per mouse, intraperitoneal). Forty-five days later, mice were immunized with the 1st vaccine dose consisting of the TcG2- and TcG4-encoding plasmids with IL-12- and GM-CSF-expression plasmids (25-μg each plasmid DNA/mouse, intramuscularly). Twenty one days after the primary immunization, mice were given 2nd vaccine dose constituted of recombinant proteins (TcG2 and TcG4, 25 μg of each protein emulsified in 5 μg saponin/100 μl PBS/mouse, intradermally). (Gupta et al., 2015)
Immune Response:
Myocardial degeneration with enlarged myocytes was particularly evident in chagasic WT mice. Therapeutic vaccination resulted in a substantial decline in myocardial and skeletal muscle levels of inflammatory infiltrate in chagasic WT mice. (Gupta et al., 2015)
l.
Mouse Response
Host Strain:
GPxtg
Immune Response:
Chronically-infected GPxtg mice presented a lower level of inflammatory infiltrate in heart and skeletal muscle therefore the antioxidants aided in arresting the chronic infiltration of the inflmamatory infiltrate in the heart in chagasic mice. (Gupta et al., 2015)
2. T. cruzi DNA prime/rTc80 + ODN-CpG boost vaccine
T. cruzi vaccine involving priming with Tc80 DNA delivered by a bacterial vector followed by a boosting with rTc80 + ODN - CpG (Bivona et al., 2018)
i.
Mouse Response
Host Strain:
C3H/HeN
Vaccination Protocol:
Mice were immunized with four doses separated by ten days. Mice received two does of Tc80 DNA delivered by the attenuated Salmonella (1x10^9 CFU/mouse) followed by two does of 10 ug rTc80 + 10 ug CpG - ODN intramuscularly. Control group mice were intramuscularly injected twice with PBS + 10 ug CpG-ODN and then two does of attenuated Salmonella carrying an empty plasmid pcDNA 3.1 orally. (Bivona et al., 2018)
Immune Response:
Mice immunized at least twice with the recombinant protein (Pboost group) elicited antibody titers considerably higher than control group. Pboost group showed an IgG2a/IgG1 ratio about 25-fold higher than rTc80im group, indicating that STc80 priming accentuated the bias towards a Th1 response. (Bivona et al., 2018)
Challenge Protocol:
Two weeks after last immunization, immunized female C3H/HeN mice were challenged intraperitoneally with 200 blood trypomastigotes of T. cruzi strain RA. (Bivona et al., 2018)
Efficacy:
Immunized groups showed a decreased parasitemia and higher survival rate compared with non-immunized control mice. Moreover, during the chronic phase of the infection, immunized mice presented: lower levels of myopathy-linked enzymes, parasite burden, electrocardiographic disorders and inflammatory cells. (Bivona et al., 2018)
Immune Response:
Vaccination with a plasmid expressing amastigote surface protein 2 (ASP-2) generates specific CD4+ Th1 and CD8+ Tc1 immune responses (Araújo et al., 2005).
Efficacy:
DNA vaccination with the gene encoding amastigote surface protein 2 (ASP-2) protects approximately 65% of highly susceptible A/Sn mice against the lethal Trypanosoma cruzi infection (Araújo et al., 2005).
Vaccination Protocol:
100 μg of pBC12BI.crp-daf DNA or vector DNA was dissolved in 50 μl of PBS and injected intramuscularly in the tibialis anterior muscles of mice that had been briefly anesthetized by metaphane inhalation (Sepulveda et al., 2000).
Challenge Protocol:
BALB/c mice immunized with DNA were challenged intravenously (i.v.) 2 weeks after the last boost with 2 × 10^6 T. cruzi strain Y trypomastigotes (Sepulveda et al., 2000).
Efficacy:
Mice immunized with the crp DNA plasmid produced antibodies capable of lysing the parasites in the presence of complement and were protected against a lethal challenge with T. cruzi trypomastigotes (Sepulveda et al., 2000).
Vaccination Protocol:
C57BL/6 mice were injected in the quadriceps muscle thrice at 2-week intervals with antigen-encoding plasmid (pCDNA3.TcG2 25 μg per DNA/mouse) and cytokine-encoding plasmids (pcDNA3.msp35, pcDNA3.msp40 [IL-12], and pCMVI.GM-CSF; 25 μg per plasmid DNA/mouse) (Bhatia and Garg, 2008).
Challenge Protocol:
Two weeks after the last immunization, mice were challenged with culture-derived T. cruzi trypomastigotes (2.5 × 10^4/mouse, intraperitoneally) and sacrificed at days 30, 75, and 120 postinfection (p.i.), corresponding to the acute phase of peak parasitemia, the intermediate phase of immune control of parasites, and the chronic phase of disease development, respectively (Bhatia and Garg, 2008).
Efficacy:
The dominant IgG2b/IgG1 antibody response was maintained after a challenge infection and was associated with 50% control of the acute-phase tissue parasite burden and an almost undetectable level of tissue parasites during the chronic phase (Bhatia and Garg, 2008).
Vaccination Protocol:
C57BL/6 mice were injected in the quadriceps muscle thrice at 2-week intervals with antigen-encoding plasmid (pCDNA3.TcG4 25 μg per DNA/mouse) and cytokine-encoding plasmids (pcDNA3.msp35, pcDNA3.msp40 [IL-12], and pCMVI.GM-CSF; 25 μg per plasmid DNA/mouse) (Bhatia and Garg, 2008).
Challenge Protocol:
Two weeks after the last immunization, mice were challenged with culture-derived T. cruzi trypomastigotes (2.5 × 10^4/mouse, intraperitoneally) and sacrificed at days 30, 75, and 120 postinfection (p.i.), corresponding to the acute phase of peak parasitemia, the intermediate phase of immune control of parasites, and the chronic phase of disease development, respectively (Bhatia and Garg, 2008).
Efficacy:
The dominant IgG2b/IgG1 antibody response was maintained after a challenge infection and was associated with 50% control of the acute-phase tissue parasite burden and an almost undetectable level of tissue parasites during the chronic phase (Bhatia and Garg, 2008).
T. cruzi DNA vaccine encoding PFR Ag coadsorbed to alum with either recombinant IL-12 or adenovirus-expressing IL-12. (Wrightsman and Manning, 2000)
g.
Mouse Response
Vaccination Protocol:
Six- to 8-week-old female C57BL/6J mice were immunized by subcutaneous (s.c.) injection with 40 μg PFR protein adsorbed to alum or emulsified with Freund's complete adjuvant. The mice were boosted twice at two-week intervals with 20 μg PFR protein adsorbed to alum or emulsified with Freund's incomplete adjuvant. Alum-PFR Ag mixtures were prepared by combining equal volumes of Rehsorpter aluminum hydroxide adsorptive gel and PFR Ag at 400 μg/ml in 0.9% saline with gentle mixing for 1 h at room temperature. In some experiments murine recombinant IL-12 (rIL-12; a generous gift from Genetics Institute, Cambridge, MA) was mixed with the PFR protein during the adsorption procedure. The amount of rIL-12 added to the mixture gave a final concentration of either 0.5 μg rIL-12/40 μg PFR (initial immunization) or 0.5 μg rIL-12/20 μg PFR (boosts). (Wrightsman and Manning, 2000)
Immune Response:
T cells and CD4+ T cells from mice immunized with either PFR Ag/Freund's or PFR Ag/alum/IL12 secreted high levels of IFN-γ in the presence of macrophages incubated with PFR Ag or macrophages infected with T. cruzi. Only negligible amounts of IFN-γ were observed with the CD8+ T cell population, and no measurable IFN-γ could be detected when any of these T cells were incubated with untreated macrophages. (Wrightsman and Manning, 2000)
Challenge Protocol:
Two weeks after the last injection, mice were challenged with s.c. injection of 102 bloodstream trypomastigotes. Following challenge, mice were checked daily, and survival was recorded at days postinfection. (Wrightsman and Manning, 2000)
8. T. cruzi DNA vaccine encoding PFR2 fused with HSP70
a. Product Name:
pCMV4-PFR2-H70
b. Type:
Recombinant vector vaccine
c. Status:
Research
d. Host Species for Licensed Use:
Mouse
e. Antigen
PFR2 and PFR3 genes (Morell et al., 2006) - paraflagellar rod proteins present in the flagellum of T. cruzi that induce an immune respons that results in reduction in the level of circulating parasites.
T. cruzi DNA vector vaccine containing the PFR2 and PFR3 genes fused to HSP70
i.
Mouse Response
Host Strain:
BALB/c + C57BL/6
Vaccination Protocol:
Groups of nine BALB/c and of five C57BL/6-A2.1/Kb mice were intramuscularly injected with 100 μg of plasmids: pCMV4 (control), pCMV4-PFR2, and pCMV4-PFR3 (carrying PFR2 and PFR3 gene, respectively) and pCMV4-PFR2-H70 and pCMV4-PFR3-H70 (bearing the PFR2-HSP70 and PFR3-HSP70 fused genes, respectively) in 100 μl. Sterile 0.9% sodium chloride solution was injected to the control group. Each mouse was immunized four times at 3-week intervals. Groups of five immunized BALB/c and B6-A2/Kb mice were used to determine the induced cellular response. (Morell et al., 2006)
Immune Response:
High antibody titers were present 2 weeks after the third dose in the sera of the BALB/c mice immunized with the constructs containing the PFR2 gene alone or fused to HSP70 gene. The mice immunized with the plasmid bearing only the PFR3 gene or fused to the HSP70 gene also reached significant anti-PFR3 reactivity after the fourth immunization. The percentage of spleen cells expressing IFN-γ and IL12 was significantly higher (p < 0.05) in mice immunized with the PFR2-HSP70 fused genes than that observed in mice that received saline solution, empty pCMV4 vector or the PFR2 coding gene alone. In the mice immunized with the PFR2-HSP70 fused genes a lower percentage of cells expressing IL4 was also observed relative to that observed in mice that received saline solution, empty pCMV4 vector or the PFR2 coding gene alone. In contrast, an increase in the number of cells expressing IL-4 was observed in mice immunized with the PFR3-HSP70 fused genes, although it was not statistically significant. (Morell et al., 2006)
Challenge Protocol:
Groups of four immunized BALB/c mice were challenged with 2.5 × 103 of attenuated trypomastigote forms 10 weeks after the last immunization. The protection assays were carried in two of the three experiments done to analyze the immune response. (Morell et al., 2006)
Efficacy:
Two out of eight control mice that received saline solution died at days 26 and 27 post-infection. One mouse of the group of eight mice inoculated with pCMV4 died at day 30 post-infection. In contrast, in mice immunized with the PFR2 gene or the PFR2-HSP70 construct circulating parasites could be detected only the first 3 weeks post-infection. Parasites could not be detected afterwards. Mice immunized with the PFR3 gene or the PFR3-HSP70 construct were able to control infection at week fourth post-infection. Controls mice controlled infection at week fifth post-infection. (Morell et al., 2006)
T. cruzi DNA vaccine encoding TcSSP4 protein emulsified in Freund's complete adjuvant aimed to induce an immune response (Arce-Fonseca et al., 2011)
g.
Mouse Response
Host Strain:
BALB/c
Vaccination Protocol:
For protein immunization, each mouse was immunized i.p. with 10 μg of rTcSSP4 protein emulsified with Freund's complete adjuvant. DNA immunizations were done twice at 2 week intervals in the tibialis anterioris muscle with the plasmids pBCSSP4 or pBk-CMV resuspended in PBS. (Arce-Fonseca et al., 2011)
Immune Response:
When compared with controls, statistically significant differences were found in IL-6 levels in mice immunized with either rTcSSP4 protein or pBCSSP4 plasmid. The IL-6 levels were higher at 3h (p<0.01) and lower at 12 h (p<0.01). For TNF-α, statistically significant differences were found in mice immunized with rTcSSP4 protein at 3 h (p<0.01) and 12 h (p<0.01) when compared with control mice, and no significant differences were found in mice immunized with pBCSSP4 plasmid. However, a clear difference was found regarding IFN-γ production; only 3 h sera from animals immunized with the pBCSSP4 plasmid showed significant amounts of this cytokine. No detectable amounts of IFN-γ were found in the other conditions. (Arce-Fonseca et al., 2011)
Challenge Protocol:
Mice immunized with the rTcSSP4 protein were challenged i.p. with 1x10^4 or 3x10^4 bloodstream trypomastigotes (BT) 3 or 7 days post-immunization. Mice immunized with DNA were challenged 2 weeks after the last immunization with 1x104 BT. Parasitemia was monitored every 3 days. (Arce-Fonseca et al., 2011)
10. T. cruzi DNA vaccine encoding TcTASV-C
a. Type:
DNA vaccine
b. Status:
Research
c. Host Species for Licensed Use:
Mouse
d. Antigen
TcTASV-C (Caeiro et al., 2020) - highly conserved antigen in different strains of T. cruzi and is mainly found in extracellular vesicles and has a great expression increment in bloodstream trypomastigotes in vivo. These features indicate that TcTASV-C may play a role during the early acute phase of infection. (Caeiro et al., 2018)
e. Immunization Route
Intramuscular injection (i.m.)
f. Description
T. cruzi DNA vaccine encoding the TcTASV-C protein adminstrated with U-Omp19
g.
Mouse Response
Host Strain:
C3H/He
Vaccination Protocol:
C3H/He mice (n = 5 per group) were vaccinated with recombinant proteins. Briefly, three doses of subcutaneous injections of mixed TcTASV-CGST and TcTASV-CHIS (25 µg each one) with a colloidal suspension of aluminum hydroxide (Sigma), 25 µg of saponin (Sigma) and/or purified 150 µg of U-Omp19-His [60], [22]. Control groups were immunized with the same procedure but with 50 μg of GST or with TcTASV-C with PBS as adjuvant. (Caeiro et al., 2020)
Immune Response:
Mice immunized with TcTASV-C and formulations with aluminum hydroxide induced a specific IgG immune response with titers higher than 6400. The TcTASV-C + U-Omp19 vaccinated group showed an IgG response similar to the group immunized with the protein alone (titer: 3200). Mixed IgG1 and IgG2a responses were observed with all the different adjuvants formulations tested. However, in the TcTASV-C + PBS group the specific response was mostly IgG1. The TcTASV-C + U-Omp19 immunization scheme induced IFN-γ and IL-17 production in a dose-dependent manner regarding the TcTASV-C concentration used for cell stimulation. This did not occur with TcTASV-C + PBS immunization or with TcTASV-C and all adjuvants together. (Caeiro et al., 2020)
Challenge Protocol:
Fifteen days after the last dose, mice were challenged with 100 bloodstream trypomastigotes of the RA strain by the intraperitoneal route. (Caeiro et al., 2020)
Efficacy:
After T. cruzi challenge, the IgG2a response was predominant, with antibodies of IgG1 isotype in surviving mice at 90 d.p.i. resulting undetectable.
11. T. cruzi DNA vaccine encoding trans-sialidase
a. Type:
DNA vaccine
b. Status:
Research
c. Host Species for Licensed Use:
Mouse
d. Antigen
trans-sialidase - In past studies, immunization of BALB/c mice with the TS gene elicited immune responses, as measured by antibody production and T-cell activation and had a significant reduction in peak parasitemia and survived lethal T. cruzi infection (Costa et al., 1998)
e. Immunization Route
Intramuscular injection (i.m.)
f. Description
T. cruzi DNA vaccine encoding the trans-sialidase gene intended to fight T. cruzi infection and induce an immune response (Rodrigues et al., 1999)
Efficacy:
Both preventive and therapeutic vaccination significantly reduced parasitemia, cardiac inflammation and cardiac parasite burden, and tended to reduce the development of cardiac arrhythmias (Quijano-Hernández et al., 2013).
Vaccination Protocol:
Groups of B6 and BALB/c mice were injected intramuscularly into each tibialis anterior muscle with 50 μg of VR1012 TSA1.7, VR1012 TSA2.1, or control VR1012 suspended in 50 μl of PBS by using a 27-gauge needle. Mice were boosted 4 weeks later with an identical dose of plasmid (100 μg total) given by the same bilateral intramuscular injection (Wizel et al., 1998).
Challenge Protocol:
Two weeks after the second dose, animals were infected by intraperitoneal injection of 10^5 (B6) or 10^3 (BALB/c) T. cruzi BFT. Parasitemias were monitored periodically by hemacytometer counts of 10 μl of tail vein blood in an ammonium chloride solution (Wizel et al., 1998).
Efficacy:
When TSA-1 DNA-vaccinated animals were challenged with T. cruzi, 14 of 22 (64%) H-2(b) and 16 of 18 (89%) H-2(d) mice survived the infection (Wizel et al., 1998).
14. T. cruzi DNA vaccine encoding TSA-1, ASP-1, ASP-2
Immune Response:
Immunization of mice with plasmids encoding ASP-1, ASP-2, or TSA-1 elicited poor antigen-specific cytotoxic-T-lymphocyte (CTL) activity and T. cruzi-specific antibody responses. Codelivery of interleukin-12 and granulocyte-macrophage colony-stimulating factor plasmids with antigen-encoding plasmids resulted in a substantial increase in CTL activity and antibody production and in increased resistance to T. cruzi infection (Garg and Tarleton, 2002).
Efficacy:
Immunization with this mixture of ts-encoding plasmids elicited moderate parasite-specific antibody responses and substantial CTL activity and subsequently provided significant resistance to T. cruzi infection. In conclusion, genetic vaccines composed of ASP-1, ASP-2, and TSA-1 provide partial protection from lethal T. cruzi infection (Garg and Tarleton, 2002).
Vaccination Protocol:
B6 mice were immunized four times at two-week intervals with 6 μg of each plasmid using a Helios Gene Gun (BioRad, NY, USA) (Chou et al., 2008).
Challenge Protocol:
Two weeks after the last vaccination, mice were infected with 1000 blood-derived T. cruzi trypomastigotes by s.c. injection at the base of the tail. Parasitemia levels were evaluated by counting the number of parasites in 5 μl of blood from the tail vein (Chou et al., 2008).
Efficacy:
C57BL/6 mice vaccinated with this plasmid showed suppressed parasitemia and prolonged survival. Vaccination with pGFP-TSA1 enhanced epitope-specific cytotoxicity and IFN-gamma secretion by CD8(+)T cells (Chou et al., 2008).
17. T. cruzi DNA vaccine pTS encoding T. cruzi antigens
Immune Response:
Vaccination of mice with pTS alone or pTS + pIL-15 elicited strong TS-specific T cell responses as detected 3 months after vaccination. In addition to enhancing TS-specific CD8+ T cell responses, the pIL-15 adjuvant enhanced TS-specific CD4+ T cell responses induced by pTS vaccination (Eickhoff et al., 2011).
Efficacy:
We challenged 5 mice per group with a lethal dose of T. cruzi BFT (5,000 BFT s.c.) 30 days following the final immunization, and followed survival for >2 months. All mice vaccinated with pTS (with or without pIL-15 co-immunization) survived lethal T. cruzi challenge, whereas all mice vaccinated with pIL-15 alone died (Eickhoff et al., 2011).
Immune Response:
The absolute number of both IFN-γ+CD8+ T cells and GZM-b+CD8+ T cells in the spleen was significantly higher in pUB-ASP-2 immunized mice. Immunization with pUB-ASP-2 promotes CD8+ T cell activation, and enhances the expression level of IFN-γ and GZM-b in CD8+ T cells (Chou et al., 2010).
Efficacy:
After being challenged with T. cruzi, mice immunized with pUB-ASP-2 developed a lower parasitemia than control pcDNA immunized groups; survival was also prolonged by immunization with pUB-ASP-2. Six out of seven pUB-ASP-2 immunized mice survived until the end of the experiment (Chou et al., 2010).
19. T. cruzi DNA-prime/MVA-boost vaccine encoding TcG2 and TcG4
a. Type:
Prime-boost vaccine with DNA vaccine priming
b. Status:
Research
c. Host Species for Licensed Use:
None
d. Antigen
TcG2 and TcG4 (Gupta and Garg, 2012) - antigens phylogenetically conserved in clinically important T. cruzi strains, expressed in infective and intracellular stages of the parasite, and recognized by parasite-specific cellular and humoral immune responses in multiple T. cruzi-infected hosts (Bhatia et al., 2004).
Two vectors: pCDA3.1 plasmid DNA vaccine vector, and the MVA vaccine vector
h. Immunization Route
Intramuscular injection (i.m.)
i. Description
The vaccine uses a DNA-prime/MVA-boost regimen, which includes two components: (1) a DNA vaccine with pCDNA3.1 encoding T. cruzi TcG2 and TcG4, and (2) a recombinant Modified Vaccinia Ankara (MVA) viral vector expressiong the same T. cruzi TcG2 and TcG4. The DNA vaccine is used for priming vaccination, and t he MVA recombinant vaccine is used for booster vaccination (Gupta and Garg, 2012).
j.
Mouse Response
Host Strain:
C57BL/6
Vaccination Protocol:
C57BL/6 mice were injected with pCDNA3.TcG2 or pCDNA3.TcG4 (25-μg/mouse, i.m.), and corresponding rMVA (106-pfu/mouse, i.d.) at 3-weeks interval (controls: empty vector). (Gupta and Garg, 2012)
Immune Response:
Mice immunized with TcG2 and TcG4 elicited a strong parasite and antigen-specific type 1 (IgG2b>IgG1) antibody response. indicating that delivery of antigens by DNA/rMVA approach primed the immunized mice to respond with pathogen-specific effector antibodies. Indeed, challenge infection resulted in a rapid and potent expansion of antibody response in immunized mice. (Gupta and Garg, 2012)
Challenge Protocol:
Two-weeks after the last immunization, mice were challenged with T. cruzi (10,000 trypomastigotes/mouse, i.p.). (Gupta and Garg, 2012)
Vaccination Protocol:
Six-to-eight-week-old female C57BL/6 mice were immunized by subcutaneous (s.c.) injection of 40 μg of pPFR or rPFR proteins co-adsorbed to alum with 0.5 μg recombinant murine IL-12 and were boosted twice at 2-week intervals with 20 μg protein co-adsorbed to alum with 0.5 μg rIL-12 (Luhrs et al., 2003).
Challenge Protocol:
Two weeks after the last injection, mice were challenged with s.c. injection of 10^2 bloodstream Peru strain trypomastigotes (Luhrs et al., 2003).
Efficacy:
rPFR-1 immunized animals were able to successfully resolve parasitemia by day 30 p.i., with the peak parasitemia occurring between days 17 and 21 p.i. (Luhrs et al., 2003).
Vaccination Protocol:
Six-to-eight-week-old female C57BL/6 mice were immunized by subcutaneous (s.c.) injection of 40 μg of pPFR or rPFR proteins co-adsorbed to alum with 0.5 μg recombinant murine IL-12 and were boosted twice at 2-week intervals with 20 μg protein co-adsorbed to alum with 0.5 μg rIL-12 (Luhrs et al., 2003).
Challenge Protocol:
Two weeks after the last injection, mice were challenged with s.c. injection of 10^2 bloodstream Peru strain trypomastigotes (Luhrs et al., 2003).
Efficacy:
rPFR-2 immunized animals were able to successfully resolve parasitemia by day 30 p.i., with the peak parasitemia occurring between days 17 and 21 p.i. (Luhrs et al., 2003).
22. T. cruzi Tc24 vaccine
a. Type:
Subunit vaccine
b. Status:
Research
c. Host Species for Licensed Use:
Mouse
d. Antigen
Tc24 (Barry et al., 2019) - Tc24 has been found to induce strong CD8+ T-cell responses in past studies and has shown promise to be effective against a wide diversity of T. cruzi parasite strains (Arnal et al., 2020)
Vaccine containing recombinant protein Tc24 formulated with an emulsion containing the Toll-like receptor 4 against E6020 to combat chronic T. cruzi infection. (Barry et al., 2019)
h.
Mouse Response
Host Strain:
BALB/c
Vaccination Protocol:
Mice were infected with T. cruzi and allowed to progress past the acute phase of disease, characterized by elevated parasitemia resolving by 40 days post-infection, before vaccination at 70 days post-infection with Tc24+E6020-SE or a sham vaccine. (Barry et al., 2019)
Immune Response:
The vaccine elicits a greater than 5-fold increase in Tc24-specific secreted IFNγ compared to the Tc24 control. IgG2a, a mouse antibody isotype associated with a TH1-bias, is most robust in the vaccine compared to the controls, further validating the cytokine results. In comparison, both the Tc24+E6020-SE vaccine and the Tc24 control produce a robust IgG1 antibody response. These results indicate that the Tc24 recombinant protein is capable of producing an antigen-specific immune response, but that the E6020-SE adjuvant is necessary to induce a favorable TH1-biasing of the resulting immune response. (Barry et al., 2019)
23. T. cruzi Tsf-ISPA vaccine
a. Type:
Subunit vaccine
b. Status:
Licensed
c. Host Species for Licensed Use:
Human
d. Antigen
TsF (trans-sialidase) - In previous studies, a trans-sialidase based vaccine was able to confer protection against a virulent T.cruzi strain, stimulating the effector immune response and decreasing C11b+ GR-1 splenocytes significantly.
e. Gene Engineering of
trans-sialidase(TsF) from Trypanosoma cruzi
A T. cruzi subunit trans-sialidase (TSf - ISPA) based vaccine which aims to target MDSCs (myeloid derived suppressor cells)
h.
Mouse Response
Host Strain:
BALB/c
Vaccination Protocol:
BALB/ mice were immunized with three subcutaneous doses, one every two weeks, containing 10ug of a fraction of the trans-sialidase protein (TSf) with 3 ul of ISPA as adjuvant. Control groups were immunized with phosphate buffered saline (PBS) solution, following the same protocol.(Gamba et al., 2021)
Immune Response:
PBS-treated mice do not tolerate a challenge with 900 Tulahuen T. cruzi parasites if MDSCs are depleted by 5FU treatment at day 15 p.i. In contrast, a proportion of TSf-ISPA-immunized and infected mice tolerated and survived infection allowing the in vivo study of the influence of MDSCs on several components of the effector and regulatory immune response during the acute phase of T. cruzi infection. TSf-ISPA immunization causes a slight but significant increase of CD11b+ GR-1+ splenocytes, here we also targeted those cells at the stage of immunization, prior to T. cruzi challenge. Notably, 5FU administration before each dose of TSf-ISPA vaccine was able to significantly ameliorate survival and decrease parasitemia levels of TSf-ISPA-vaccinated and infected mice.(Gamba et al., 2021)
Challenge Protocol:
Mice were challenged intraperitoneally with 900 or 1500 bloodstream trypomastigotes of Tulahuen strain, as indicated, 15 days after the last immunization.(Gamba et al., 2021)
This prime-booster vaccine encoding ASP2 alongside rapamycin treatment is made by having pCDNA plasmid encoding ASP2 and a recombinant replication-deficient human adenovirus type 5 (HuAd5) vaccine vector also encoding ASP2 (Rigato et al., 2011),; futhermore, the rapamycin treatment is used as an adjuvant to enhance the vaccine immune response (Moraschi et al., 2021).
h.
Mouse Response
Host Strain:
C57BL/6
Vaccination Protocol:
The protocol consists of a dose of plasmid DNA, with the vectors pcDNA3 (control) or pIgSPClone9, at 10 or 100 μg/mouse. Three weeks after the first immunization, mice were immunized with 2 x 10^7 or 2 x 10^8 pfu of the adenoviral vectors Adβ-Gal (control) or AdASP-2. Both immunizations were performed by intramuscular route in the Tibialis anterior muscle. Experimental groups were delineated as follows: 1) Control: immunized with the control vectors pcDNA3 and Adβ-Gal; 2) ASP2: immunized with pIgSPCl.9/AdASP-2 and vehicle-injected (PBS); 3) ASP2/rapamycin: immunized with pIgSPCl.9/AdASP-2 and rapamycin-treated. Mice were treated every 24 hours with 2 μg rapamycin (Sigma Aldrich) per mouse (0.075 mg/kg/day), diluted in 0.2 mL PBS via intraperitoneal (i.p.) for 34 days, starting at priming. Control mice were treated with the vehicle (PBS) (Moraschi et al., 2021).
Immune Response:
The number of CD8+ T-cells that simultaneously express IFNγ, TNF and CD107a, named polyfunctional subpopulation, were increased in rapamycin-treated mice (Gr.3), compared with vehicle-injected mice (Gr.2). the magnitude of responding CD8+ T-cells (frequency of cells that express at least one of the three molecules IFNγ or TNF or CD107a after ex vivo stimulus with the specific peptide) was also higher in rapamycin treated mice (Moraschi et al., 2021).
Vaccination Protocol:
All mice (female BALB/c mice 6–8 weeks old) were randomly assigned into control or vaccinated groups of eight mice each. 100 μg of recombinant plasmid (pBKTcENO) or vector DNA (pBK-CMV) (Stratagene) was dissolved in 50 μL of sterile PBS, injected intramuscularly (i.m.) in the tibialis anterioris muscle and boosted twice every 2 weeks. Two weeks after the last immunization, they received an i.p. injection of 8 × 104 bloodstream trypomastigotes of T. cruzi. (Arce-Fonseca et al., 2018)
Immune Response:
The immunizations with pBKTcENO induced a significant production of IgGs against the rTcENO antigen seven days after the last immunization. The mice immunized with pBKTcENO showed IgG2a>IgG2b>IgG1 with an IgG2b/IgG1 ratio > 1, suggesting that a predominantly Th1-like immune response was induced. The pBKTcENO plasmid reduced the parasite load in the mice at 70% and 42% during the parasitemia peak (day 24 after challenge) compared to the PBS and pBK-CMV controls, respectively. All mice immunized with pBKTcENO eventually died, not exceeding day 33 post-infection. (Arce-Fonseca et al., 2018)
26. T. cruzi vaccine encoding recombinant enolase from H8 strain
Vaccine encoding rTcENO (recombinant enloase) from the H8 strain emulsified in Freund's Complete Adjuvant and Freund's Incomplete Adjuvant (Arce-Fonseca et al., 2018)
i.
Mouse Response
Host Strain:
BALB/c
Vaccination Protocol:
All mice were randomly assigned into control or vaccinated groups of eight mice each in two independent experiments. The mice were immunized by intraperitoneal (i.p.) injection with 10 μg of the recombinant protein (rTcENO) emulsified in Freund's complete adjuvant (CFA) (Sigma) and boosted twice with 10 μg of the rTcENO in Freund's incomplete adjuvant (IFA) every 2 weeks. were randomly assigned into control or vaccinated groups of eight mice each in two independent experiments. The mice were immunized by intraperitoneal (i.p.) injection with 10 μg of the recombinant protein (rTcENO) emulsified in Freund's complete adjuvant (CFA) (Sigma) and boosted twice with 10 μg of the rTcENO in Freund's incomplete adjuvant (IFA) every 2 weeks. (Arce-Fonseca et al., 2018)
Immune Response:
The immunizations with rTcENO induced a significant production of IgGs against the rTcENO antigen seven days after the last immunization. Antigen-specific isotypes of immunoglobulins in the sera of immunized animals with rTcENO revealed high levels of IgG1>IgG2b>IgG2a, indicating that this antigen induced a mixed Th1-/Th2-like immune response. The mice immunized with rTcENO exhibited high titers of antibodies compared to the control groups inoculated with PBS or pBK-CMV. (Arce-Fonseca et al., 2018)
Challenge Protocol:
Challenged the immunized mice with a lethal dose of T. cruzi. The mice immunized with rTcENO showed typical immunoglobulins for Th1/Th2 immune responses, a significant reduction in the level of parasite burden in the blood, and 75% survival rate in comparison to the control groups. Moreover, the detection of IFN-γ, TNF (alpha and beta), and IL-2, but not IL-4, showed a polarized Th1 immune response when mice were challenged with T. cruzi. (Arce-Fonseca et al., 2018)
T. cruzi sub-unit vaccine formulated with recombinant Tc80 plus oligodeoxynucleotides CpG (ODN-CpG) as adjuvant. (Bivona et al., 2018)
i.
Mouse Response
Host Strain:
C3H/HeN
Vaccination Protocol:
Mice were immunized with four doses separated by ten days intramuscularly in the quadriceps with 10ug of rTc80 adjuvanted with 10 ug of ODN-CpG 1826. Control group mice were intramuscularly injected twice with PBS + 10 ug CpG-ODN and then two does of attenuated Salmonella carrying an empty plasmid pcDNA 3.1 orally. (Bivona et al., 2018)
Immune Response:
Mice elicited antibody titers considerably higher than control group. Splenocyts from all immunized mice were able to secrete IL-2 and IFN-y upon antigen recall. Mice presented a higher percentage of IFN-y and TNF-a producing CD4+ T cells compared with control group. (Bivona et al., 2018)
Challenge Protocol:
Two weeks after the last dose of vaccination protocols, immunized male C3H/HeN mice were challenged intraperitoneally with 2.5x105 blood trypomastigotes of the sub-lethal T. cruzi strain K98. (Bivona et al., 2018)
Efficacy:
All immunized mice presented significantly reduced parasitemias during the acute phase of infection compared to the control. rTc80im group achieved the highest control of parasitemia. (Bivona et al., 2018)
28. T. cruzi vaccine encoding TcG2 and TcG4
a. Type:
DNA vaccine
b. Status:
Research
c. Host Species for Licensed Use:
Human
d. Antigen
TcG2 and TcG4 (Gupta et al., 2019) - antigens phylogenetically conserved in clinically important T. cruzi strains, expressed in infective and intracellular stages of the parasite, and recognized by parasite-specific cellular and humoral immune responses in multiple T. cruzi-infected hosts (Bhatia et al., 2004).
A DNA vaccine containing recombinant proteins TcG2 and TcG4 formulated with fTr (fixed T. rangeli) epimastigotes (Gupta et al., 2019).
j.
Mouse Response
Host Strain:
C57BL/6
Vaccination Protocol:
Mice were vaccinated in following groups: DNA vaccine only, two doses; DNA vaccine + fTr, two doses; DNA vaccine + QA, two doses; DNA vaccine + fTr + QA, two doses. To determine if fTr boosts the DNA vaccine-induced immune responses, mice were vaccinated with DNA vaccine followed by fTr (gp5) or fTr+QA (gp6). Each dose of DNA vaccine was constituted of 25-μg of each plasmid (pCDNA3.TcG2 and pCDNA3.TcG4) and delivered in 100 μl PBS by intramuscular (im) injection in the hind thighs. When used, fTr (1 × 108 Tr in 100 μl PBS) was delivered by subcutaneous (sc) injection. When added, vaccine was emulsified with 5 μg QA per dose per mouse. Non-vaccinated (N) mice were used as controls. Prime and booster doses of vaccine were given at 21-day intervals. (Gupta et al., 2019)
Immune Response:
TcG2/TcG4 vaccine adjuvanted with fTr also resulted in maximal levels of Tc-specific IgG sub-types. Tr-specific IgGs constituted of IgG1, IgG2a, and IgG2b subtypes were also detected in mice that received fTr as an adjuvant with TcG2/TcG4 DNA or as a booster vaccine, and maximal Tr-specific antibodies were measured in sera of mice given fTr as an adjuvant with TcG2/TcG4. (Gupta et al., 2019)
Challenge Protocol:
Mice were immunized, challenged with Tc (10,000 trypomastigotes/mouse, intraperitoneal) at 21 days after the 2nd vaccine dose, and euthanized at 21 days' post-infection (pi). Non-vaccinated mice infected with Tc (T) and euthanized at similar time-points were used as controls. (Gupta et al., 2019)
29. T. cruzi Vaccine TcVac2
a. Type:
DNA vaccine
b. Status:
Research
c. Host Species for Licensed Use:
Human
d. Antigen
TcG1, TcG2, and TcG4 (Gupta and Garg, 2010) - T. cruzi encoding plasmids which have elicited a strong Th1 - type antibody response dominated by immunoglobin G2b (IgG2b)/IgG1 isotypes. (Bhatia and Garg, 2008)
TcVAc2 is a DNA-prime/protein-boost subunit vaccine (TcVac2) constituted of candidate antigens (TcG1-, TcG2-, and TcG4) along with adjuvants IL-12 and GM-CSF.(Gupta and Garg, 2010)
k.
Mouse Response
Host Strain:
C57BL/6
Vaccination Protocol:
C57BL/6 mice were injected in the quadriceps muscle twice at three-week intervals with antigen-encoding plasmids and cytokine-encoding plasmids. Mice were then immunized with two doses of TcG1-, TcG2-, and TcG4- recombinant proteins (25 µg each, total 75 µg protein emulsified in 5 µg saponin/100 µl PBS/mouse, intra-dermal). (Gupta and Garg, 2010)
Immune Response:
We detected a substantial level of TcTL- and TcG1-, TcG2- and TcG4-specific IgG antibodies in mice immunized with TcVac2. The level of antigen-specific antibody response was detected in the order of TcG4>TcG2>TcG1; and the antigen-specific antibody response was predominantly of the Th1 type with IgG2b/IgG1 ratio>1. (Gupta and Garg, 2010)
Challenge Protocol:
Two weeks after the last immunization, mice were challenged with T. cruzi (10,000 trypomastigotes/mouse, i.p.).(Gupta and Garg, 2010)
30. T. cruzi Vaccine TcVac3 encoding TcG2 and TcG4
a. Type:
DNA vaccine
b. Status:
Research
c. Host Species for Licensed Use:
Baboon
d. Antigen
TcG2 and TcG4 (Gupta and Garg, 2013) - T. cruzi encoding plasmids which have elicited a strong Th1 - type antibody response dominated by immunoglobin G2b (IgG2b)/IgG1 isotypes. (Bhatia and Garg, 2008)
DNA-prime/MVA-boost vaccine (TcVac3) constituted of antigenic candidates (TcG2 and TcG4) (Gupta and Garg, 2013)
l.
Mouse Response
Host Strain:
C57BL/6
Vaccination Protocol:
Mice were injected with antigen-encoding plasmids with our without IL-12 and GM-CSF encoding plasmids. Three weeks later, mice were given booster vaccine constituted of rMVA.TcG2 and rMVA.TcG4. Mice injected with empty vectors were used as controls. (Gupta and Garg, 2013)
Challenge Protocol:
Two weeks after the last immunization, mice were challenged with T. cruzi. Mice were sacrificed at day 30 and 120-post infection corresponding to the acute phase of peak parasitemia and the chronic phase of disease development, respectively. (Gupta and Garg, 2013)
31. T. cruzi Vaccine TcVac4
a. Type:
Prime-boost vaccine with DNA vaccine priming
b. Status:
Research
c. Host Species for Licensed Use:
Human
d. Host Species as Laboratory Animal Model:
dog
e. Antigen
TcG1, TcG2, and TcG4 (Aparicio-Burgos et al., 2015) - T. cruzi encoding plasmids which have elicited a strong Th1 - type antibody response dominated by immunoglobin G2b (IgG2b)/IgG1 isotypes. (Bhatia and Garg, 2008)
A DNA - prime/T. rangeli - boost (TcVac4) vaccine encoding TcG1, TcG2, and TcG4 antigens plus IL-12 and GM-CSF-encoding plasmids(Aparicio-Burgos et al., 2015)
m.
Dog Response
Host Strain:
Mongrel
Vaccination Protocol:
Randomly assigned dogs to the following groups: a) pcDNA3.1/ no Tc(empty plasmid DNA and no challenge infection, n = 6); b) pcDNA3.1/Tc (empty plasmid followed by Tc challenge infection, n = 6); c) TcVac4/Tc (two doses of DNA vaccine followed by two doses of TrIE and challenge infection, n = 6); and d) TrIE/Tc (two doses of TrIE followed by challenge infection, n = 3). Each dose of DNA vaccine was delivered at two sites; intramuscular (180 μg each DNA in 0.9 ml PBS) and intradermal (20 μg each DNA in 0.1 ml PBS). TrIE vaccine was also delivered at two sites; subcutaneous (0.9x109 TrIE in 0.9 ml PBS-saponin) and intradermal (1x108 TrIE in 0.1 ml PBS- saponin).(Aparicio-Burgos et al., 2015)
Immune Response:
Immunization with TcVac4, delivered as two doses of subunit DNA vaccine and two doses of TrIE, elicited a strong parasite-specific IgG response with predominance of IgG2 subtype (IgG2/IgG1 = 2.7). Upon challenge infection, IgG1 response was expanded and IgG2 response barely changed, resulting in a balanced IgG2/IgG1 ratio (0.95) in TcVac4/Tc dogs. (Aparicio-Burgos et al., 2015)
Challenge Protocol:
Challenge infection with T. cruzi (3.5 x 10^3 culture-derived trypomastigotes/kg body weight, intraperitoneally) was performed six weeks after the last vaccine dose. The selected dose of the parasites was sufficient to produce acute parasitemia within 1–2 weeks of inoculation, and electrocardiographic changes within 6–8 weeks post-infection. All dogs were observed daily for general physical condition, at weekly intervals for clinical condition, and at 2-week intervals for cardiac function.(Aparicio-Burgos et al., 2015)
32. T. cruzi vaccine using attenuated Salmonella expressing T. cruzi Cruzipain
Vaccination Protocol:
Mice were vaccinated four times intranasally with control and cruzipain-expressing salmonella cells. The mice were lightly anesthetized with ketamine-xylazine given intraperitoneally, and salmonella vaccines were administered in 10-μl volumes of PBS. A total of 2 × 10^6 CFU of salmonella was given for primary vaccinations, and 2 × 10^7 CFU of salmonella was given for booster vaccinations. The second vaccinations were given 4 weeks after the priming doses, and the three booster vaccinations were given at 2-week intervals (Schnapp et al., 2002).
Challenge Protocol:
One month after the final vaccinations, the mice were challenged orally with 2,000 T. cruzi IMT (Schnapp et al., 2002).
Efficacy:
As early as 15 days after immunization, the parasitemias detected in the cruzipain-immunized group were significantly lower than those in the phage10-immunized and unimmunized groups. Significantly reduced parasitemias persisted in the cruzipain-immunized group throughout the remainder of the first month postchallenge (Schnapp et al., 2002).
33. T. cruzi vaccine using Sendai virus vector expressing amastigote surface protein-2
Vaccination Protocol:
B6 mice were administrated intranasally with 5 × 10^6 CIU SeV-GFP or SeV-ASP2 (Duan et al., 2009).
Challenge Protocol:
For challenge infections, mice were inoculated with 1000 blood-derived trypomastigotes at the base of the tail 2 weeks after immunization (Duan et al., 2009).
Efficacy:
C57BL/6 mice immunized intranasally with rSeV/dF expressing ASP2 showed significantly suppressed parasitemia and could be protected from lethal T. cruzi challenge (Duan et al., 2009).
A T. cruzi attenuated bacterial Salmonella vector vaccine delivering the Tc80 gene.
j.
Mouse Response
Host Strain:
C3H/HeN
Vaccination Protocol:
Mice received 4 doses of attenuated Salmonella carrying a Tc80-coding eukaryotic plasmid separated by ten days via oral administration (1x10^9 CFU/mouse). Control group mice were intramuscularly injected twice with PBS + 10 ug CpG-ODN and then two does of attenuated Salmonella carrying an empty plasmid pcDNA 3.1 orally. (Bivona et al., 2018)
Immune Response:
STc80 group which was immunized only with Tc80 DNA carried by Salmonella, did not elicit significant specific antibody titer comparing to SaroA. Antibodies isotypes reflected a Th1-biased response since IgG2a levels were higher than IgG1. Splenocytes from all immunized mice were able to secrete IL-2 and IFN -y upon antigen recall. STc80 group presented a significantly higher percentage of IFN-y or TNF-a producing CD4+ T cells. (Bivona et al., 2018)
Challenge Protocol:
Two weeks after last immunization, immunized female C3H/HeN mice were challenged intraperitoneally with 200 blood trypomastigotes of T. cruzi strain RA. (Bivona et al., 2018)
Efficacy:
All immunized mice presented significantly reduced parasitemias during the acute phase of infection compared to the control. (Bivona et al., 2018)
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