Conservation of type-specific B-cell epitopes of glycoprotein G in clinical herpes simplex virus type 2 isolates.
Glycoprotein G (gG-2) of herpes simplex virus type 2 (HSV-2) is cleaved to a secreted amino-terminal portion and to a cell-associated, heavily O-glycosylated carboxy-terminal portion that constitutes the mature gG-2 (mgG-2). The mgG-2 protein is commonly used as a type-specific antigen in the serodiagnosis of HSV-2 infection. As the amino acid sequence variability of mgG-2 in clinical isolates may affect the performance of such assays, the gG-2 gene was sequenced from 15 clinical HSV-2 isolates. Few mutations were identified, and these were mostly localized outside the epitope regions described earlier. Five isolates were identical to different laboratory strains, indicating that the gG-2 gene is highly conserved over time. In the search for HSV-2 isolates harboring mutations within the immunodominant region of mgG-2, a pool of 2,400 clinical HSV-2 isolates was tested for reactivity with two anti-mgG-2 monoclonal antibodies (MAbs). Ten MAb escape HSV-2 mutants, which all harbored structurally restricted single- or dual-point mutations within the respective epitopes explaining the loss of binding, were identified. Sera from corresponding patients were reactive to mgG-2, as well as to a peptide representing the immunodominant region, suggesting that the point mutations detected did not diminish seroreactivity to mgG-2. The conservation of the gG-2 gene reported here further supports the use of mgG-2 as a type-specific antigen in the diagnosis of HSV-2 infections.
Liljeqvist
J A
JA
Department of Virology, Göteborg University, S-413 46 Göteborg, Sweden. jan-ake.lijeqvist@microbio.gu.se
Svennerholm
B
B
Bergström
T
T
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology; D018985:Epitopes, B-Lymphocyte; D018258:Herpesvirus 2, Human / Q000235:genetics / Q000276:immunology*; D006801:Humans; D008969:Molecular Sequence Data; D017354:Point Mutation; D014759:Viral Envelope Proteins / Q000235:genetics / Q000276:immunology*
D000911:Antibodies, Monoclonal; D018985:Epitopes, B-Lymphocyte; D014759:Viral Envelope Proteins; C044525:glycoprotein B, herpes simplex virus type 2