Background: Most of the studies of HIV-1 infection in South America have be
en limited to Brazil and little is known about the viral variants that ar c
ausing disease elsewhere in the continent. Aim: To determine the characteri
stics of the viral variants present in Chile as well as patterns of viral t
ransmission. Material and methods: Viral sequences were obtained form 21 HI
V-1 infected people from Santiago, Chile who were infected either via sexua
l contact or intravenous drug use. Cloned sequences obtained from both the
third variable and conserved regions of the envelope as well as the viral p
rotease were evaluated. Results: We found only clade B subtype viruses in S
antiago. An evaluation of the envelope gene revealed no evidence that the s
equences were monophyletic by risk group. A number of the protease sequence
s were predicted to encode amino acid substitutions commonly found during s
election for protease inhibitor resistance. Conclusions: The HIV-1 strains
studied in Chile, belong to the subtype B. There is no molecular evidence o
f separate introductions of the virus into the different risk groups. A num
ber of substitutions in the protease gene that may confer resistance to pro
tease inhibitors were found in patients with no previous exposure to this c
lass of drugs.