EUROPEAN BROWN HARE SYNDROME VIRUS - RELATIONSHIP TO RABBIT HEMORRHAGIC-DISEASE VIRUS AND OTHER CALICIVIRUSES

Monoclonal antibodies directed against the capsid protein of rabbit he morrhagic disease virus (RHDV) were used to identify field cases of Eu ropean brown hare syndrome (EBHS) and to distinguish between RHDV and the virus responsible for EBHS. Western blot (immunoblot) analysis of liver extract of an EBHS virus (EBHSV)-infected hare revealed a single major capsid protein species of approximately 60 kDa that shared epit opes with the capsid protein of RHDV. RNA isolated from the liver of a n EBHSV-infected hare contained two viral RNA species of 7.5 and 2.2 k b that comigrated with the genomic and subgenomic RNAs of RHDV and wer e recognized by labeled RHDV cDNA in Northern (RNA) hybridizations. Th e nucleotide sequence of the 3' 2.8 kb of the EBHSV genome was determi ned from four overlapping cDNA clones. Sequence analysis revealed an o pen reading frame that contains part of the putative RNA polymerase ge ne and the complete capsid protein gene. This particular genome organi zation is shared by RHDV but not by other known caliciviruses. The ded uced amino acid sequence of the capsid protein of EBHSV was compared w ith the capsid protein sequences of RHDV and other caliciviruses. The amino acid sequence comparisons revealed that EBHSV is closely related to RHDV and distantly related to other caliciviruses. On the basis of their genome organization, it is suggested that caliciviruses be divi ded into three groups.