Serotyping of HIV type 1 infections: Definition, relationship to viral genetic subtypes, and assay evaluation

V3 serotyping refers to a system based on binding of antibody in patient sera to V3-loop peptides derived from HIV-1 env genetic subtypes, The V3(X) serotype represents reactivity of serum from an HIV-1-infected patient (regardless of viral genetic subtype), which reacts preferentially to a V3 peptide derived from the X subtype sequence, We have classified HIV-1 serotypes, determined the relationship between the HIV-1 V3 serotypes and viral genetic subtypes in a large study (n = 125), and evaluated the performance of three different V3 peptide-binding assays, Seven HIV-1 V3 serotypes mere identified: A, B, B-Br, B-Th, C, D, and E, Serotypes B-Br and B-Th represent sera that react specifically to peptides derived from Brazilian B (B-Br, GWGR) and Thai B (B-Th, GPGQ) Strains, The HIV-1 V3 B, C, and E serotypes correlated Closely with their viral env genetic subtypes; 19-26 of 32 B sera (59-79%), 3-4 of 4 C sera (75-100%), and 19-22 of 23 E sera (83-96%) mere identified as serotypes B, C, and E, respectively, In contrast, two major V3 serotypes were classified in A sera: A (14-18 of 36 [40-50%]) and C (12-19 of 36 [33-54%]), Similarly, two major V3 serotypes were classified in D sera: B (6-10 of 20 [30-50%]) and D (9-12 of 20 [45-60%]), Serotyping of subtype E sera showed the best concordance with genetic subtypes by all assays, Overall, HIV-1 V3 serotyping produced consistent results among three laboratories, However, HIV-1 V3 serotypes do not distinguish all HIV-1 genetic subtypes, The relative biological significance of the V3 serotypes remains to be elucidated.