Development of recombinant diagnostic reagents based on pp85(U14) and p86(U11) proteins to detect the human immune response to human herpesvirus 7 infection

Human antibodies raised in response to human herpesvirus 7 (HHV-7) infectio n are directed predominantly to one or more HHV-7-infected cell proteins,vi th apparent molecular masses of about 85 to 89 kDa, The genes that encode t hese proteins are unknown, However, several HHH-7 genes that possibly encod e proteins in this molecular mass range have been identified. Thus, the pro teins encoded by open reading frame U14 (85 kDa) and U11 (86 kDa) were expr essed as recombinant proteins in bacteria. Of 13 human serum specimens that recognized the 85- to 89-kDa protein(s) of HHV-7-infected cells by immunob lotting, 12 were also reactive with recombinant pp85(U14) and 8 were reacti ve with p86(U11), It is concluded that (i) the HHV-7 immunodominant protein is pp85(U14) and (ii) the lack of posttranslational modifications in proca ryotically expressed pp85 does not adversely affect the reactivity of human sera. Monoclonal antibody (MAb) 5E1 is an HHV-7-specific MAb directed to p p85(U14). Here, the HHV-7-specific epitope in pp85(U14) was finely mapped t o the C' terminal region between amino acid residues 484 and 502, However, as indicated by the low level of reactivity of human sera with the HHV-7-sp ecific epitope recognized by MAb 5E1, human sera recognize additional epito pes of pp85(U14) that are required for their full reactivity.