HIV TYPE-1 VARIATION IN WORLD-HEALTH-ORGANIZATION-SPONSORED VACCINE EVALUATION SITES - GENETIC SCREENING, SEQUENCE-ANALYSIS, AND PRELIMINARY BIOLOGICAL CHARACTERIZATION OF SELECTED VIRAL STRAINS

A laboratory network has been established by the World Health Organiza tion (WHO) to systematically isolate and characterize HIV strains from different parts of the world, and to obtain information and reagents that would facilitate HIV vaccine development. Sixty-three HIV-1 isola tes obtained from 224 specimens collected during 1992-1993 in Brazil, Rwanda, Thailand, and Uganda were characterized in this initial study. Virus strains were first genetically subtyped using three different s creening methodologies: PCR-gag fingerprinting, RNase A mismatch, and heteroduplex mobility assay (HMA). In addition, selected viruses were sequenced in V3 (52 strains), C2-V3 (42 strains), gp120 (15 strains), and/or gp160 (8 strains) regions of their envelope genes. These studie s identified viruses belonging to different sequence subtypes in the f our countries: 16 subtype B and 1 subtype C strains in Brazil, 13 subt ype A strains in Rwanda, 15 subtype E and 2 subtype B strains in Thail and, and 3 subtype A and 13 subtype D strains in Uganda. Comparison of sequence data with results from the genetic screening efforts identif ied the HMA as a rapid and reliable method for sequence subtype determ inations. The majority of strains were collected from persons document ed to have recently seroconverted to HIV-1 positivity, and most strain s were found to have slow replication and low cytopathic characteristi cs and to be non-syncytium-inducing (slow/low-NSI phenotypes) in vitro , which, in many cases, correlated with the corresponding genotype and charge of the V3 loop amino acid sequences. This collection of HIV st rains is presently being characterized immunologically and serological ly, including neutralization assays, to define whether there are immun ological correlates of the sequence subtypes. Identification of potent ial immunotypes would be of considerable importance for the further de velopment of HIV vaccines.