Protection of rainbow trout (Oncorhynchus mykiss) against VHSV genotype Ia and IHNV by immunization with VHSV genotype IVa backbone-based single-cycle viruses

So Yeon Kim; Jae Young Kim; Hyoung Jun Kim; Min Sun Kim; Ki Hong Kim

doi:10.1016/j.fsi.2022.108476

Protection of rainbow trout (Oncorhynchus mykiss) against VHSV genotype Ia and IHNV by immunization with VHSV genotype IVa backbone-based single-cycle viruses

Fish Shellfish Immunol. 2023 Jan:132:108476. doi: 10.1016/j.fsi.2022.108476. Epub 2022 Dec 5.

Authors

So Yeon Kim¹, Jae Young Kim², Hyoung Jun Kim³, Min Sun Kim¹, Ki Hong Kim⁴

Affiliations

¹ Department of Biological Sciences, Kongju National University, Gongju, 32588, South Korea.
² Department of Aquatic Life Medicine, Pukyong National University, Busan, 48513, South Korea.
³ OIE Reference Laboratory for VHS, National Institute of Fisheries Science, Busan, 46083, South Korea.
⁴ Department of Aquatic Life Medicine, Pukyong National University, Busan, 48513, South Korea. Electronic address: khkim@pknu.ac.kr.

PMID: 36481290
DOI: 10.1016/j.fsi.2022.108476

Abstract

To evaluate the protective effect of viral hemorrhagic septicemia virus genotype IVa (VHSV IVa) genome-based single-cycle viruses against VHSV genotype Ia (VHSV Ia) and infectious hematopoietic necrosis virus (IHNV) in rainbow trout, three kinds of single-cycle VHSVs were rescued using reverse genetic technology: i) rVHSV-IaGΔTM^-IVaG containing the transmembrane and cytoplasmic region-deleted G protein (GΔTM) of VHSV Ia instead of VHSV IVa full G gene ORF and having VHSV IVa G proteins on the envelope; ii) rVHSV-IaGΔTM^-IaG containing VHSV Ia GΔTM instead of VHSV IVa full G gene ORF and having VHSV Ia G proteins on the envelope; iii) rVHSV-IaGΔTM-ihnvGΔTM^-IVaG containing not only VHSV Ia GΔTM instead of full G gene but also IHNV GΔTM instead of NV gene and having VHSV IVa G proteins on the envelope. Rainbow trout immunized with rVHSV-IaGΔTM^-IaG and rVHSV-IaGΔTM^-IVaG showed significantly higher serum antibody titers against both VHSV Ia and VHSV IVa, and showed no mortality against VHSV Ia infection, while fish in the control groups showed 100% mortalities. Fish immunized with rVHSV-IaGΔTM-ihnvGΔTM^-IVaG showed significantly higher serum antibody titers against VHSV IVa, VHSV Ia, and IHNV compared to fish in the control group. Immunization with rVHSV-IaGΔTM-ihnvGΔTM^-IVaG induced significantly higher protection against not only VHSV Ia but also IHNV. These results suggest that the present single-cycle rVHSV-based system can be used as a platform to produce combined vaccines that can protect fish from multiple pathogenic species. However, the mechanism of the high protection against IHNV despite comparatively low antibody titer remains to be investigated.

Keywords: Bivalent vaccine; IHNV; Reverse genetics; Single-cycle virus; VHSV genotype IVa; VHSV genotype Ia.

MeSH terms

Animals
Fish Diseases* / prevention & control
Genotype
Hemorrhagic Septicemia, Viral*
Immunization
Infectious hematopoietic necrosis virus* / genetics
Novirhabdovirus*
Oncorhynchus mykiss*
Rhabdoviridae Infections*