Antigenic structure of the Murray Valley encephalitis virus E glycoprotein.

To complement our battery of St Louis encephalitis (SLE) virus monoclonal antibodies (MAbs), we isolated and characterized MAbs reactive with another member of the SLE virus serocomplex, Murray Valley encephalitis (MVE) virus. From 40 fusion products, we isolated 10 stable hybridomas. The combination of SLE and MVE virus MAbs defined eight epitopes on the MVE envelope (E) glycoprotein. Six of these epitopes (E-1a, E-1c, E-1d, E-3, E-4a, E-4b) were identical to those previously demonstrated on SLE virus. Two new epitopes (E-5 and E-6) were also identified. As with SLE virus, the MVE E-1c epitope elicited the most potent virus-neutralizing and protective MAb. Unlike SLE virus, however, one of the cross-reactive epitopes (E-5) elicited neutralizing antibody and protected animals from MVE virus challenge. These results indicate that, while the antigenic domains on viruses within the SLE virus serocomplex are quite similar, epitopes involved in virus neutralization or protection from virus challenge may vary and can be topologically distinct.