Temperature and pH requirements for viral haemorrhagic septicemia virus induced cell fusion

Abstract

The rhabdovirus causing viral haemorrhagic septicemia (VHS), an important disease of salmonids, induced formation of large syncytia in fish cell monolayers by cell fusion. For maximal percentage of fusion, not only was a pH of 5.6 needed but also a temperature of at least 14°C. The fusion was dependent on the G protein of VHSV as shown by inhibition of fusion with specific anti-G polyclonal and monoclonal antibodies. Part of the region of the G protein involved in fusion was mapped to amino acids 82 to 109 because anti-peptide antibodies binding to that region also inhibited fusion. The fusion assay described here can be useful for studying the functionality of the G protein of fish rhabdoviruses in the early steps of infection and this information can, in turn, help to designing effective vaccination and/or therapeutic strategies against fish rhabdoviruses. The described fusion assay could also he applied to other fish rhabdoviruses such as infectious haematopoietic necrosis virus (IHNV) anti spring viraemia of carp virus (SVCV).