Viral Hemorrhagic Septicemia (VHS) is a deadly fish virus and aquatic invasive species that attacks and weakens the blood vessels of fish. Broken blood vessels and severe blood loss ultimately causes death. It afflicts more than 50 species of freshwater and marine fish in several parts of the northern hemisphere. Scientists are not sure how the virus arrived. It may have come in with migrating fish, or may have hitchhiked in ballast water from ships. VHS was first found in European freshwater trout in the late 1930s and continues to cause epidemics in European trout farms. It appeared on the U.S. West Coast in 1988 in marine trout and salmon (WISC - VHSV).
The first 64 participants received the YF vaccine from one lot. Immediately after the administration of the YF vaccine subcutaneously into the deltoid, immunoglobulin (Ig) or saline injections were administered intramuscularly into the upper outer quadrants of the buttocks. The placebo for Ig was sterile saline (0.9% sodium chloride injection, USP; Hospira Inc., Lake Forest, IL) administered similarly. Participants returned on post-vaccination days 1, 2, 3, 5, 7, 9, 11, 14, 30, and 91 for determination of viremia and immunological and safety assessment. (Edupuganti et al., 2013)
g. Immunization Route
Intramuscular injection (i.m.)
h. Description
Yellow fever (YF) virus vaccine with human immunoglobulin (Ig) that contained YF virus-neutralizing antibodies. (Edupuganti et al., 2013)
2. VHSV DNA vaccine pCMV-vhsG encoding glycoprotein G
Efficacy:
Young rainbow trout injected with the G construct, alone or together with the N construct, were strongly protected against challenge with live virus (Heppel et al., 1997).
3. VHSV DNA vaccine pCMV-vhsN encoding nucleocapsid protein N and glycoprotein G
Efficacy:
Young rainbow trout injected with the G construct together with the N construct were strongly protected against challenge with live virus (Heppel et al., 1997).
Efficacy:
Challenge experiments revealed that immunity established shortly after vaccination was cross-protective between the VHSV and IHNV whereas no increased survival was found upon challenge with bacterial pathogens. Within two months after vaccination, the cross-protection disappeared while the specific immunity to homologous virus remained high (Lorenzen et al., 2002).
VHSV (10 TCID50/mL) was inactivated by adding 0.3% formalin with continuous stirring using a magnetic stirrer at 4 ◦C for 24 h. Complete inactivation of the inactivated VHSV (IV) was confirmed by re- inoculation into FHM cells and infection in olive flounder. The combination of saponin and chitosan was used for the evaluation of survival rate at two different concentrations (0.29 and 2.9 mg/g of fish body weight/day). Adjuvant mixtures were mixed using a magnetic stirrer. IV (10^8.8 TCID50/mL) (50% of the total volume) was added to each combination and homogenised on ice for 15 min using PolytronPT 1200E homogeniser (Kinematica, Switzerland) followed by gentle vortexing. (Jung et al., 2022)
g. Immunization Route
oral
h. Description
Inactivated VHSV vaccine using Chitosan adjuvant protects olive flounder against VHSV challenge. (Jung et al., 2022)
i.
Fish Response
Vaccination Protocol:
Trial III was conducted to study the duration of protection of saponin (0.29 or 2.9 mg) + IV (inactivated virus), chitosan (0.29 or 2.9 mg) + IV, and saponin (0.29 or 2.9 mg) + chitosan (0.29 or 2.9 mg) + IV vaccines. In this study, for primary immunisation, 120 fish (12.1 ± 0.2 g, 10.4 ± 0.6 cm) in each group were orally administered saponin + IV, chitosan + IV, and saponin + chitosan + IV. Each formulation was mixed with feed constituting 1% of total body weight and orally administered for 10 days. Additionally, 120 fish in the non-administered (virus-injected control) and naive groups were maintained at 21–23 ◦C in tanks (200 L) with continuous supply of seawater and aeration. (Jung et al., 2022)
Side Effects:
The group administered 2.9 mg of chitosan displayed severe red liver after 14 days of initial administration. Therefore, our results indicated that oral administration of chitosan at a dose of 2.9 mg (2916 mg/kg of fish) was toxic to olive flounder. (Jung et al., 2022)
Challenge Protocol:
At 4, 9, 14, and 20 wpv (weeks post vaccination), each group of 15 fish was infected with VHSV (106.8 TCID50/100 μL/fish) via i. p. route and maintained for 21, 21, 35, and 91 days, respectively, in an aquarium containing 30 L of UV-treated seawater at 15 ◦C. All survivors from 20 wpv groups (Trial III) at 70 dpi were re-challenged with VHSV. The survivors were administered vaccines containing saponin + IV (10 and 9 fish), chitosan + IV (9 and 8 fish) and saponin + chitosan + IV (10 and 10 fish), respectively, for the administration doses of 0.29 and 2.9 mg. (Jung et al., 2022)
Efficacy:
For the first challenge, the RPS values obtained after were 15%, 0%, 42.9%, and 25% (0.29 mg chitosan + IV), and 10%, 0%, 0%, and 12.5% (2.9 mg chitosan + IV) for the respective challenge time points. For re-challenge, the survival rate was 100% for chitosan (2.9 mg) + IV and 80% in the chitosan (0.29 mg) + IV group. Specific mortality was observed after six days in the virus-infected control group (not previously exposed to virus) with characteristic clinical signs of VHSV and 100% mortality rate at 12 dpi. (Jung et al., 2022)
VHSV (10 TCID50/mL) was inactivated by adding 0.3% formalin with continuous stirring using a magnetic stirrer at 4 ◦C for 24 h. Complete inactivation of the inactivated VHSV (IV) was confirmed by re- inoculation into FHM cells and infection in olive flounder. The combination of saponin and chitosan was used for the evaluation of survival rate at two different concentrations (0.29 and 2.9 mg/g of fish body weight/day). Adjuvant mixtures were mixed using a magnetic stirrer. IV (108.8 TCID50/mL) (50% of the total volume) was added to each combination and homogenised on ice for 15 min using PolytronPT 1200E homogeniser (Kinematica, Switzerland) followed by gentle vortexing. (Jung et al., 2022)
g. Immunization Route
oral
h. Description
Inactivated VHSV vaccine using mixture of Saponin and Chitosan adjuvants protects olive flounder against VHSV challenge. (Jung et al., 2022)
i.
Fish Response
Vaccination Protocol:
Trial III was conducted to study the duration of protection of saponin (0.29 or 2.9 mg) + IV (inactivated virus), chitosan (0.29 or 2.9 mg) + IV, and saponin (0.29 or 2.9 mg) + chitosan (0.29 or 2.9 mg) + IV vaccines. In this study, for primary immunisation, 120 fish (12.1 ± 0.2 g, 10.4 ± 0.6 cm) in each group were orally administered saponin + IV, chitosan + IV, and saponin + chitosan + IV. Each formulation was mixed with feed constituting 1% of total body weight and orally administered for 10 days. Additionally, 120 fish in the non-administered (virus-injected control) and naive groups were maintained at 21–23 ◦C in tanks (200 L) with continuous supply of seawater and aeration. (Jung et al., 2022)
Side Effects:
Results indicated toxic effects of saponin at a concentration of 2.9 mg/fish. The group administered 2.9 mg of chitosan displayed severe red liver after 14 days of initial administration. These observations suggested that a combination containing saponin and chitosan, each at a concentration of 0.29 mg (291.6 mg/kg of fish), was less toxic and acceptable for vaccination studies. (Jung et al., 2022)
Challenge Protocol:
At 4, 9, 14, and 20 wpv (weeks post vaccination), each group of 15 fish was infected with VHSV (106.8 TCID50/100 μL/fish) via i. p. route and maintained for 21, 21, 35, and 91 days, respectively, in an aquarium containing 30 L of UV-treated seawater at 15 ◦C. All survivors from 20 wpv groups (Trial III) at 70 dpi were re-challenged with VHSV. The survivors were administered vaccines containing saponin + IV (10 and 9 fish), chitosan + IV (9 and 8 fish) and saponin + chitosan + IV (10 and 10 fish), respectively, for the administration doses of 0.29 and 2.9 mg. (Jung et al., 2022)
Efficacy:
For first challenge, at 4, 9, 14, and 20 wpv, the RPS values obtained after administration were 15%, 26.7%, 42.9%, and 37.5% (0.29 mg saponin +0.29 mg chi- tosan + IV), and 10%, 26.7%, 42.9%, and 37.5% (2.9 mg saponin +2.9 mg chitosan + IV) for the respective challenge time points. For re-challenge, survival rate was 100% for saponin (0.29 and 2.9 mg) + chitosan (0.29 and 2.9 mg) + IV. Specific mortality was observed after six days in the virus-infected control group (not previously exposed to virus) with characteristic clinical signs of VHSV and 100% mortality rate at 12 dpi. (Jung et al., 2022)
VHSV (10 TCID50/mL) was inactivated by adding 0.3% formalin with continuous stirring using a magnetic stirrer at 4 ◦C for 24 h. Complete inactivation of the inactivated VHSV (IV) was confirmed by re- inoculation into FHM cells and infection in olive flounder. The combination of saponin and chitosan was used for the evaluation of survival rate at two different concentrations (0.29 and 2.9 mg/g of fish body weight/day). Adjuvant mixtures were mixed using a magnetic stirrer. IV (10^8.8 TCID50/mL) (50% of the total volume) was added to each combination and homogenised on ice for 15 min using PolytronPT 1200E homogeniser (Kinematica, Switzerland) followed by gentle vortexing. (Jung et al., 2022)
g. Immunization Route
oral
h. Description
Inactivated VHSV vaccine using Saponin adjuvant protects olive flounder against VHSV challenge. (Jung et al., 2022)
i.
Fish Response
Vaccination Protocol:
Trial III was conducted to study the duration of protection of saponin (0.29 or 2.9 mg) + IV (inactivated virus), chitosan (0.29 or 2.9 mg) + IV, and saponin (0.29 or 2.9 mg) + chitosan (0.29 or 2.9 mg) + IV vaccines. In this study, for primary immunisation, 120 fish (12.1 ± 0.2 g, 10.4 ± 0.6 cm) in each group were orally administered saponin + IV, chitosan + IV, and saponin + chitosan + IV. Each formulation was mixed with feed constituting 1% of total body weight and orally administered for 10 days. Additionally, 120 fish in the non-administered (virus-injected control) and naive groups were maintained at 21–23 ◦C in tanks (200 L) with continuous supply of seawater and aeration. (Jung et al., 2022)
Side Effects:
Results indicated toxic effects of saponin at a concentration of 2.9 mg/fish (2916 mg/kg of fish); therefore, a concentration below 1.45 mg/fish is recommended as safe for administration to olive flounder. (Jung et al., 2022)
Challenge Protocol:
At 4, 9, 14, and 20 wpv (weeks post vaccination), each group of 15 fish was infected with VHSV (10^6.8 TCID50/100 μL/fish) via i. p. route and maintained for 21, 21, 35, and 91 days, respectively, in an aquarium containing 30 L of UV-treated seawater at 15 ◦C. All survivors from 20 wpv groups (Trial III) at 70 dpi were re-challenged with VHSV. The survivors were administered vaccines containing saponin + IV (10 and 9 fish), chitosan + IV (9 and 8 fish) and saponin + chitosan + IV (10 and 10 fish), respectively, for the administration doses of 0.29 and 2.9 mg. (Jung et al., 2022)
Efficacy:
After first challenge, the RPS values obtained after vaccine administration were 20%, 13.4%, 14.3%, and 37.5% (0.29 mg saponin + IV), and 10%, 26.7%, 28.6%, and 25% (2.9 mg saponin + IV) for the respective challenge time points. After re-challenge. survival rate was 100% in saponin (0.29 and 2.9 mg) + IV. Specific mortality was observed after six days in the virus-infected control group (not previously exposed to virus) with characteristic clinical signs of VHSV and 100% mortality rate at 12 dpi. (Jung et al., 2022)
IV. References
1. Heppel et al., 1997: JOËL HEPPELL, NIELS LORENZEN, NEIL K. ARMSTRONG, TONG WU, ELLEN LORENZEN, KATJA EINER-JENSEN, JOACHIM SCHORR, HEATHER L. DAVIS. Development of DNA vaccines for fish: vector design, intramuscular injection and antigen expression using viral haemorrhagic septicaemia virus genes as model. Fish & Shellfish Immunology. 1997; 8(4); 271-286.
2. Lorenzen et al., 2002: Lorenzen N, Lorenzen E, Einer-Jensen K, LaPatra SE. Immunity induced shortly after DNA vaccination of rainbow trout against rhabdoviruses protects against heterologous virus but not against bacterial pathogens. Developmental and comparative immunology. 2002; 26(2); 173-179. [PubMed: 11696382].
3. Standish et al., 2016: Standish IF, Millard EV, Brenden TO, Faisal M. A DNA vaccine encoding the viral hemorrhagic septicemia virus genotype IVb glycoprotein confers protection in muskellunge (Esox masquinongy), rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta), and lake trout (Salvelinus namaycush). Virology journal. 2016; 13(1); 203. [PubMed: 27912771].
