Molecular characterization of cyprinid herpesvirus 3 (CyHV-3) major capsid protein (MCP) and its impact on immune gene expression in vitro

Authors

1 Hubei Key Laboratory of Animal Nutrition and Feed Science, School of Animal Science and Nutritional Engineering, Wuhan Polytechnic University, Wuhan, China

2 Technology Center of Wuhan Customs, Wuhan, China

10.22092/ijfs.2025.134332

Abstract

Main chitin protein (MCP) is a crucial component of cyprinid herpesvirus 3 (CyHV-3), also known as koi herpesvirus (KHV), found on the surface of the viral capsid. It plays a vital role in protecting viral DNA and assembling viral particles, contributing to the virus's high infectivity and lethality. This study aims to characterize the MCP-encoded protein of CyHV-3, investigate its subcellular localization, and assess its impact on the expression of immune factors through in vitro experiments. Our findings revealed that the CyHV-3 MCP protein consists of 579 amino acids. Despite analyzing evolutionary trees of homologous proteins from three carp herpesvirus sources, no significant similarities were observed. Subcellular localization experiments indicated that the green fluorescent signal of the pEGFP- MCP protein predominantly diffused within the cytoplasm. Remarkably, overexpression of MCP significantly suppressed the expression of immune factors in Channel Catfish Ovary (CCO) and Epithelioma papulosum cyprinid (EPC) cell lines, highlighting its role as a viral immune escape factor. These results enhance our understanding of the immune function of CyHV-3 MCP and provide a theoretical foundation for developing new vaccines against CyHV-3 infections. These results provide further insights into the immune function of CyHV-3 MCP and provide a theoretical basis for the development of new vaccines against CyHV-3 virus infection.

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