PRODUCTION AND CHARACTERIZATION OF MONOCLONAL-ANTIBODIES AGAINST VARIANT-A INFECTIOUS BURSAL DISEASE VIRUS

Monoclonal antibodies (MAbs) were produced against a variant subtype of infectious bursal disease virus (IBDV) from Delaware variant isolate A (Var-A). Splenocytes from immunized mice were fused to myeloma cells, and antibody-producing hybridomas were screened by dot-blot enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence (IF) against the homologous isolate. Specificity of the MAbs was tested against viral isolates representing all six serologic subtypes of IBDV and three untyped IBDVs-GLS, Ark, and Miss-found in serotype 1 by dot-blot ELISA and IF. The MAb G11 recognized all isolates, whereas H7 did not recognize two viruses in subtype 1, the Lukert strain and APHIS. MAbs G11 and H7 were not neutralizing and identified both the precursor proteins (VP2a) and protein product (VP2b of VP2) in Western immunoblots. Results showed an antigenic determinant in IBDV isolates and antigenic variation between subtype 1 viruses and other subtypes. This confirms and extends previous work that showed that IBDVs evolved from subtype 1 by alteration or substitution of antigenic sites.