• Vaccine Ontology ID: VO_0011450
• Type: Subunit vaccine
• Status: Research
• Antigen: E. histolytica alkyl hydroperoxide reductase Eh29
• gEh29 gene engineering:
  • Type: Recombinant protein preparation
  • Description: The full coding region of the gEh29 gene which encodes Eh29 (GenBank Accession No. X70996.1) was amplified by PCR and the 0.7 Kb amplicon was cloned into the expression vector pRSET-A (Invitrogen, CA, USA) following standard methods. After transformation into Escherichia coli BL21 (DE3) pLysS (Stratagene, CA, USA) positive clones were selected on ampicillin and chloramphenicol and were induced for expression of amino-terminal His-tagged Eh29 by incubation with 2 mM IPTG (Carrero et al., 2010).
  • Detailed Gene Information: Click Here.
• Adjuvant:
  • VO ID: VO_0000142
• Immunization Route: Intraperitoneal injection (i.p.)

• Vaccine Ontology ID: VO_0011451
• Type: Subunit vaccine
• Status: Research
• Antigen: E. histolyica Gal/GalNAc lectin
• Gal/GalNAc lectin gene engineering:
  • Type: Recombinant protein preparation
  • Description: The native E. histolytica Gal/GalNAc lectin was purified from strain HM1:IMSS trophozoites grown under axenic conditions as described previously [5]. A large fragment of the Gal/GalNAc lectin heavy subunit spanning amino acids 578–1154 (“LecA”) was cloned into a pRSET-A vector (Invitrogen, Carlsbad, CA) with a kanamycin resistance gene and expressed in E. coli. The E. coli cells were lyzed by sonication and isolated inclusion bodies were denatured in inclusion body solubilization reagent (Pierce, Rockford, IL) (Houpt et al., 2004).
  • Detailed Gene Information: Click Here.
• Adjuvant:
  • VO ID: VO_0000139
• Adjuvant:
  • VO ID: VO_0000142
• Immunization Route: Intraperitoneal injection (i.p.)

Mouse Response

• Host Strain: C3H/HeJ
• Vaccination Protocol: Mice were divided into seven groups of 10 animals. Two groups were left unimmunized. The remaining five groups were immunized using Eh29 combined with CT (Eh29 + CT), Eh29–CTxB fusion protein, CT alone, CTxB alone, or ARF combined with CT (ARF + CT). Mice were immunized orally with a dose of the relevant protein solution on days 1, 7, and 21 using a plastic cannula (standard wall spaghetti tubing; Chemplast Inc., USA). The protein solutions were prepared in 0.2 M NaHCO3, pH 8.3 such that one dose contained 100 μg of either recombinant Eh29, Eh29–CTxB or ARF, and 10 μg of commercial CT or CTxB, as pertinent. Additionally, on day 14, all immunized groups received an intraperitoneal boost with 25 μg of the corresponding recombinant protein emulsified in incomplete Freund’s adjuvant. The groups receiving only CT or CTxB were boosted with adjuvant emulsified in PBS (Carrero et al., 2010).
• Challenge Protocol: On day 27 all mice (except those from one of the unimmunized groups) were infected intracecally with E. histolytica trophozoites recovered after three passages from hamster liver abscesses (Carrero et al., 2010).
• Efficacy: 80% of C3H/HeJ mice immunized with Eh29 administered in combination with a subclinical dose of whole cholera toxin, but not as an Eh29-CTxB fusion, showed no evidence of infection in tissue sections harvested following intracecal challenge with virulent E. histolytica trophozoites. These results suggest that Eh29 is capable of inducing protective anti-amoebic immune responses in mice following oral immunization and could be used in the development of oral vaccines against amoebiasis (Carrero et al., 2010).

Mouse Response

• Host Strain: C3H/HeJ
• Vaccination Protocol: Mice were immunized with a combined intranasal and intraperitoneal regimen over 6–9 weeks. Intranasal immunizations used 10 μg of antigen and 1 μg of cholera toxin (Sigma) administered intranasally in 20 μl of PBS into C3H mice under isoflurane anesthesia. Intraperitoneal immunizations used 15 μg of antigen emulsified in equal volumes of either complete (CFA) or incomplete Freund’s adjuvant (IFA) (Gibco, Grand Island, NY) injected via 20 gauge syringe. The lectin-1 trial utilized 150 μl of complete Freund’s adjuvant, the week 4 immunization of the lectin-2 trial two utilized 100 μl of CFA, and all other i.p. immunizations utilized 150 μl of incomplete Freund’s adjuvant. Sham-immunized mice from each trial were administered an identical regimen of PBS with adjuvant (Houpt et al., 2004).
• Challenge Protocol: Mice were challenged intracecally with trophozoites 2 weeks after the final immunization (Houpt et al., 2004).
• Efficacy: Vaccination prevented intestinal infection with efficacies of 84 and 100% in the two native lectin trials and 91 and 34% in the two LecA trials. Results show for the first time that immunization with the Gal/GalNAc lectin can prevent intestinal amebiasis in mice (Houpt et al., 2004).