IDENTIFICATION AND CHARACTERIZATION OF THE MAJOR PROTEINS OF MALIGNANT CATARRHAL FEVER VIRUS

Malignant catarrhal fever virus (MCFV), a gamma-herpesvirus, causes a severe inflammatory and lymphoproliferative disease of cattle and othe r susceptible ruminants. Polyclonal antisera and monoclonal antibodies (MAbs) to the Minnesota isolate of MCFV were produced and used to exa mine the characteristics of the viral proteins. Immunoprecipitation of antigens of the Minnesota isolate of MCFV with polyclonal antisera re vealed at least 11 proteins with molecular masses ranging from 17 kDa to 145 kDa. Among 279 candidate anti-MCFV hybridomas, 14 were selected and clustered into six groups on the basis of the patterns of reactiv ity to viral proteins in immunoprecipitation and immunoblot. The group I MAbs exhibited strong neutralizing activity and recognized a glycos ylation-dependent conformational epitope on a 110 kDa protein. The MAb s in group II bound a non-neutralizing conformational epitope on a 130 kDa non-glycosylated protein. A glycosylated protein complex of 115/1 10/105/78/45 kDa moieties was identified by the MAbs in group III. The MAbs in groups IV, V and VI reacted with nonglycosylated proteins of 36/34 kDa, 24 kDa and 17 kDa, respectively. Comparison of three MCFV i solates [the Minnesota isolate, the Austrian isolate (Au-732) and the African prototype isolate (WC-11)] revealed no apparent differences in immunoprecipitation patterns with the single exception that the 110 k Da protein of WC-11 was slightly smaller than its counterpart in the M innesota isolate.