Genetic and serologic characterization of HIV type 1 prevailing in Myanmar (Burma).

To study the molecular epidemiology of HIV-1 spread in Myanmar and the interplay with the epidemic in surrounding Southeast Asian countries, we determined the HIV-1 subtypes prevailing in Myanmar. Thirty HIV-positive blood specimens were sampled in the capital city, Yangon, and an additional 459 sera were collected nationwide in 1995. Genetic subtyping based on the env C2/V3 sequence and serologic data, using a V3 peptide enzyme immunoassay (PEIA), revealed three patterns of HIV spread in different geographic regions in Myanmar: (1) in the capital city, Yangon, HIV-1 subtype B' ("Thai-B" cluster within subtype B) predominated both in IDUs and heterosexuals; (2) in the cities near the border with Thailand, including Tachelaik and Kawthaung, where heterosexual transmission is a major pathway of HIV-1 spread, HIV-1 subtype E was predominantly distributed among the commercial sex workers and heterosexuals; (3) in central and northeast Myanmar, both HIV-1 subtypes B' and E occurred in a mixed distribution, without showing any significant segregation by risk group. In addition, the PEIA data implied the occurrence of other subtype(s) in these areas. The interperson nucleotide sequence variations in env C2/V3 regions of B' and E, prevailing in Yangon, were 6.7 +/- 2.1 and 7.1 +/- 0.7%, respectively. They were similar to those levels observed in Thailand. These findings are consistent with the view that HIV spread in Myanmar might have taken place at about the same time as that in Thailand, and that multiple entries and exchanges of HIV-1 with neighboring countries are important factors contributing to the current distribution of subtypes in Myanmar.

Emergence of new forms of human immunodeficiency virus type 1 intersubtype recombinants in central Myanmar.

We have previously shown that HIV-1 env subtypes B' (a Thai-B cluster within subtype B) and E (CRF01_AE) are distributed in Yangon, the capital city of Myanmar. However, HIV strains from the rest of country have not yet been genetically characterized. In the present study, we determined env (C2/V3) and gag (p17) subtypes of 25 specimens from central Myanmar (Mandalay). Phylogenetic analyses identified 5 subtype C (20%), in addition to 10 CRF01_AE (40%) and 4 subtype B' (16%). Interestingly, the remaining six specimens (24%) showed discordance between gag and env subtypes; three gag subtype B'/env subtype C, one gag subtype B'/env subtype E, one gag subtype C/env subtype B', and one gag subtype C/env subtype E. These discordant specimens were found frequently among injecting drug users (4 of 12, 33%) and female commercial sex workers (2 of 8, 25%) engaging in high-risk behaviors. The recombinant nature of these HIV-1 strains was verified in three specimens, indicating the presence of new forms of HIV-1 intersubtype C/B' and C/B'/E recombinants with different recombination breakpoints. The data suggest that multiple subtypes of B', C, and CRF01_AE are cocirculating in central Myanmar, leading to the evolution of new forms of intersubtype recombinants among the risk populations exhibiting one of the highest HIV infection rates in the region.

Local evaluation of a rapid HIV assay for use in developing countries.

We present a research scheme for evaluating inexpensive HIV rapid tests in a developing country setting and assess the field validity of the Sero Strip HIV 1/2 rapid test. The research design features the random allocation of 100 true HIV-positive and 100 true HIV-negative serum specimens to 4 groups, followed by blind testing for HIV status. After one short training session, laboratory technicians at 4 township hospitals (25-35 beds) located 20-50 km from Yangon, Myanmar were sent 800 sera labelled with only an identification number and divided into four groups of 200 specimens each, half being HIV-positive and half HIV-negative. Testing was done in the field with the Sero-Strip HIV 1/2. Determination of the test's validity was based on 399 true HIV positive and 401 true HIV negative sera. All true positives were correctly identified, as were all but two of the true negatives. The sensitivity (% of true positives that test positive) was 100%, and the specificity (% of true negatives that test negative) was 99.5%. The research was completed by in-country scientists who are best suited to evaluate the validity of HIV tests conducted in local environments.

Stability of saliva for measuring HIV in the tropics.

If HIV is to be detected among pregnant women in remote regions of the tropics, HIV antibodies need to remain stable until specimens arrive at the laboratory. Our objective was to assess the stability of HIV antibodies in saliva held for up to 1 month at ambient temperature in Yangon, Myanmar. We gathered 10 saliva specimens from each of 102 HIV-infected persons with the Omni-Sal collection device (Saliva Diagnostic Systems, Inc.), and for each subject, divided the saliva into 15 portions. During 33 days, the 102 saliva specimens, kept at ambient temperature, were tested every 2-3 days for HIV antibodies (total 1530 assays) with the GACELISA (Murex Diagnostics Ltd), a highly sensitive test designed for use with saliva. We observed no reduction in test performance over 33 days, indicating that the antimicrobial and antiproteolytic transport medium in the Omni-Sal device can preserve HIV antibodies without refrigeration for up to a month before saliva specimens reach the laboratory.