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

The rhabdovirus causlng v ~r a l haemorrhaglc septlcema (VHS), an Important disease of salmonlds, Induced forrnatlon of large syncytia in fish cell monolayers by cell fusion For maximal percentage of fus~on, not only was a pH of 5 6 needed but also a temperature of at least 14C The fusion was dependent on the G proteln of VHSV as shown by inhibition of fuslon with speclflc anti-G polyclonal and monoclonal antibodies Part of the region of the G proteln Involved In fusion was mapped to amino acids 82 to 109 because anti-peptide antibodies blndlng to that reglon also inhlblted fuslon The fusion assay descnbed here can b e useful for studying the functionality of the G proteln of fish rhabdovlruses in the early steps of Infection and thls information can In turn, help to designing effectwe vaccination and/or therapeutic strategies against fish rhabdovlruses The descnbed fusion assay could also be a p p l ~e d to other flsh rhabdoviruses such as infect~ous haematopoletic necrosls virus (IHNV) and spnng viraemia of carp vlrus (SVCV) KEY WORDS Viral haemorrhagic septicaemia Rhabdovirus Neutrahzing-enhancing a n t ~b o d y Monoclonal antibodies Fusion