LACK OF CORRELATION BETWEEN V3-LOOP PEPTIDE ENZYME-IMMUNOASSAY SEROLOGIC SUBTYPING AND GENETIC SEQUENCING

Objective: To compare the performance of V3-loop peptide enzyme immuno assay (PEIA) methodologies from four different laboratories for subtyp ing HIV-1, and to determine the causes for the lack of correlation bet ween V3-loop PEIA serotyping and subtyping by sequencing. Materials an d methods: Synthetic peptides derived from the amino-acid consensus se quences of the V3-loop of group M strains representing genetic subtype s A-F as well as reference strains were evaluated in PEIA by four diff erent laboratories for their ability to accurately determine the subty pe in a panel of 85 sera obtained from persons infected with known HIV -1 subtypes (28 subtype A, 34 subtype B, four subtype C, 10 subtype D, seven subtype F, one each of subtype H and C). Furthermore, the V3 lo op of the corresponding virus was compared with the V3 loop of the pep tides used in PEIA. Results: The correlation between HIV-1 subtyping b y sequencing and V3-loop PEIA from the different laboratories varied c onsiderably for the different HIV-1 subtypes: subtype A (46-68%), B (3 8-85%), C (75-100%), D (29-50%), and F (17-57%). A 70% agreement betwe en PEIA and sequencing subtypes was observed for samples with the conc ordant presence of the same octameric sequences in the V3 loop of the virus and the V3 loop of the peptide used in PEIA; however, only 42% o f specimens with different V3-loop octameric viral and peptide sequenc es yielded concordant results in V3-loop serotyping and genetic subtyp ing. Conclusion: Our results indicate that V3-loop PEIA methodologies used in different laboratories correlate poorly with genetic subtyping , and that their accuracy to predict HIV-1 subtypes in sera of Belgian individuals infected with different HIV-1 subtypes (A, B, C, D, F, G and H) vary considerably. The poor correlation between serotyping and genetic subtyping was partly due to the simultaneous occurrence of sub type-specific octameric sequences at the tip of the V3 loop of viruses belonging to different genetic subtypes. (C) 1998 Lippincott-Raven Pu blishers.