Characterization of aquabirnaviruses from flounder Pseudopleuronectes americanus and mummichog Fundulus heteroclitus in the Chesapeake Bay, Virginia, USA

Viruses were isolated in cell culture from tissue homogenates of flounder Pseudopleuronectes americanus and mummichog Fundulus heteroclitus in the Chesapeake Bay, Virginia, USA. Neutralization and immunofluorescence tests with aquabirnavirus (West Buxton strain)-specific polyclonal antisera indicated that both viruses were aquabirnaviruses belonging to Serogroup A, the most common aquabirnavirus serogroup in the United States. This was confirmed by RT-PCR, with primers targeting the VP3 and VP2 gene of aquabirnaviruses. The VP2-specific RT-PCR cDNA amplification product was sequenced and deduced amino-acid sequences were compared with known sequences of the type strains of the 9 serotypes of aquabirnavirus Serogroup A. This demonstrated that the viruses from both flounder and mummichog belong to aquabirnavirus Genogroup 1. The flounder isolate exhibited deduced amino acid sequence similarities of 98.1 % with the Jasper strain of serotype A9, and 97.7 % with the West Buxton strain of serotype A1. The isolate from mummichog exhibited deduced amino acid sequence similarities of 99.1 % with the West Buxton strain of Serotype A1 and 94.8 % with the Jasper isolate of Serotype A9. Similarities of deduced amino acid sequences ranged from 79.9 to 86.9 %, with representatives of the other 7 serotypes. This is the first report of an aquabirnavirus from mummichog F heteroclitus and only the fifth report of an aquabirnavirus from a flounder species.