Characterization of neutralizing domains on varicella-zoster virus glycoprotein E defined by monoclonal antibodies

The genome of varicella-zoster virus (VZV), encodes at least six glycoproteins and they elicit the formation of complement-independent, complement-dependent, and non-neutralizing antibody responses. We have used our library of MAbs to VZV glycoprotein E (gE) to determine the neutralizing epitopes of gE, and shown that gE has 3 distinct neutralizing domains. In this report we have used the baculovirus expression system to identify the antigenic domains of gE. We have generated 3 recombinant baculoviruses, expressing the full-length gE and two overlapping truncated forms (the amino-terminal and the carboxy-terminal) of gE. By immuno-fluorescence and immunoblotting we have explored the physical interactions of Mabs to gE on these constructs. Our panel of MAbs revealed 3 district antigenic domains on gE. All MAbs reacted with the full-length gE; MAbs with high titered complement-dependent neutralizing activities reacted with the N-terminal truncated gE; MAbs with low titered or non-neutralizing activities reacted with the C-terminal truncated gE; MAbs with complement-enhanced neutralizing activities reacted with both truncated constructs. However, although the antibody binding in immunofluorescence and immunoblotting was carried out under denatured conditions, whereas the neutralization is under non-denatured conditions, still the antigenic mapping was similar in both conditions.