HIV

HIV-1 Surveillance in Vietnam: Correlation between V3 Peptide-Based Serotyping and Sequence-Based Genotyping.

T.H. Pham^a, F. Isami^a, S. Alexander^b, H. T. Nguyen^c, J. Jone^b, R. De Leys^b, C.K. Pham^c, R. Detels^d, L. T. Hoang^c, R. Yanagihara^a, and V. R. Nerurkar^a.
^{aRetrovirology Research Laboratory, Pacific
Biomedical Research Center, University of Hawaii at Manoa, Honolulu,
Hawaii; ^bOrtho Clinical Diagnostics, Ratitan, New Jersey;^cNational Reference Laboratory on HIV/AIDS, Sub-Committee of
HIV/AIDS Surveillance, National Institute of Hygiene and Epidemiology,
Hanoi, Vietnam; ^dDepartment of Epidemiology, School of Public
Health, University of California at Los Angeles, California.}
Objective: To develop a sensitive and rapid HIV-1 serotyping assay, to better monitor the spread of HIV-1 subtypes in Vietnam.

Methods: An enzyme immunoassay (EIA) was developed using N-terminal biotinylated peptides based on sequences of gp120 V3 loop of HIV-1 subtype E from Vietnam and subtype B from Thailand. Serum or plasma from 132 HIV-1-infected individuals, collected between 1995 and 1999 as part of the national HIV sentinel surveillance program and HIV/AIDS case reporting in Vietnam, were tested against both peptides, and the optical densities (O.D) were compared. An O.D. ratio of >2.0 for Vietnam E: Thai B peptide or for Thai B: Vietnam E were considered seroreactive for Vietnam E and Thai B, respectively. All specimens were genotyped by HIV-1 env gene nucleotide sequence and phylogenetic analyses.

Results: Of the 129 specimens, which were phylogenetically classified as subtype E, 128 (99.2%) were correctly typed by EIA, while one was nonreactive against both peptides. Similarly, of the three samples classified as Thai subtype B by sequencing, two were confirmed by serotyping and one was nonreactive.

Conclusions: Our data demonstrate that an HIV-1 V3 loop peptide-based EIA was highly sensitive in correctly identifying genotype-confirmed HIV-1 subtype E specimens from Vietnam. In addition, this peptide-based EIA was capable of differentiating HIV-1 Thai subtype B and Vietnam subtype E. This cost-effective EIA has potential usefulness for rapid surveillance of HIV-1 subtypes in high-risk behavior groups in Vietnam. [Supported by grants from the Research Centers in Minority Institutions Program, NCRR, NIH (G12 RR/AIRR3061) and from the World AIDS Foundation]