HIV genetic variability, phylogenetic relationships, and transmission dynam
ics were analyzed in 26 HIV-infected patients from Lebanon. Twenty-five spe
cimens were identified as HIV-1 and one as HIV-2 subtype B. The 25 strains
were classified into six env-C2-V3 HIV-1 subtypes: B (n = 10), A (n = 11),
C (n = 1), D (n = 1), G (n = 1), and unclassifiable. Potential recombinants
combining parts of viral regions from different subtypes A(env)/D-pol/A(ga
g), G(env)/A(pol), and the unclassifiable-subtype(env)/unclassifiable-subty
pe(pol)/A(gag) were found in three patients. Epidemiologic analysis of trav
el histories and behavioral risks indicated that HIV-1 and HIV-2 subtypes r
eflected HIV strains prevalent in countries visited by patients or their se
x partners. Spread of complex HIV-subtype distribution patterns to regions
where HIV is not endemic may be more common than previously thought. Blood
screening for both HIV-1 and HIV-2 in Lebanon is recommended to protect the
blood supply. HIV subtype data provide information for vaccine development
.