The spread of the human immunodeficiency virus type 1 (HIV-1) is by now virtually worldwide. An understanding of the genetic, biological, and immunological differences among isolates collected in different geographic locales is crucial for the development of globally effective vaccines. Here we report the genetic characteristics of 21 HIV-1 isolates from Brazil. The isolates were initially characterized using a heteroduplex mobility assay. The majority (17 of 21) were related to North American/European reference isolates of genetic subtype B. Four isolates belonged to a more recently identified genotype, termed subtype F. The subtype F sequences from Brazil are distinguishable in both gag and env from five other genetic subtypes of HIV-1 currently recognized. Like many locales, Brazil harbors more than one HIV-1 subtype.

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Between October 15, 1985, and March 31, 1989, serum specimens from 1 141 164 teenaged youths (aged less than 20 years) who applied for entry into the US military were tested for antibodies to the human immunodeficiency virus. Overall, 393 teenaged applicants were found to be seropositive (prevalence, 0.34 per 1000). Prevalences varied markedly in different geographic locales: less than 0.1 per 1000 throughout the north-central states, compared with greater than 2 per 1000 in urban counties in Maryland, Texas, New York, and the District of Columbia. Overall, rates among teenaged males (345/991 445; prevalence, 0.35 per 1000) and teenaged females (48/150 013; prevalence, 0.32 per 1000) were comparable. The prevalence among black teenaged applicants (1.06 per 1000) was greater than that among white (0.18 per 1000) or Hispanic (0.31 per 1000) teenaged applicants. Infections with the human immunodeficiency virus are not rare among teenaged Americans.

To examine the genetic and antigenic characteristics of HIV-1 in Indonesia, samples from 19 HIV-positive volunteers were studied. By a combination of PCR typing and DNA sequence analysis, 12 of the 19 volunteers were determined to be infected with HIV-1 clade B and seven with clade E. Six of the seven Indonesian clade E isolates were from volunteers associated with the Indonesian Military during a peacekeeping mission in Cambodia. Infectivity reduction neutralization assays showed that the Indonesian E viruses were effectively neutralized by Thailand clade E HIV-1 antisera but not by U.S. clade B antisera. The Indonesian clade B virus tested was neutralized by U.S. clade B antisera and not by the Thailand E antisera. Using a previously described serologic typing ELISA based on clade B and E V3 peptides, genetic clade was accurately determined in eight of eight sera tested. This is the first report of the genetic and antigenic analysis of HIV-1 isolates from Indonesia. The data indicate that at least two genetic and antigenic HIV-1 clades (clade E and B) circulate in Indonesia.