EVIDENCE FOR HIV TYPE-1 STRAINS OF US INTRAVENOUS-DRUG-USERS AS FOUNDERS OF AIDS EPIDEMIC AMONG INTRAVENOUS-DRUG-USERS IN NORTHERN EUROPE

To establish an epidemiological link between HIV-1 epidemics in U.S. a nd European homosexual men and intravenous drug users (IVDUs) we analy zed the HIV-1 gp120 V3 sequences in both risk groups. Signature patter n analysis revealed that the V3 sequences of viruses from IVDUs in Nor thern Europe are distinguishable from those of homosexual men on the b asis of one amino acid and two synonymous nucleotide substitutions, wh ich the most conserved was a synonymous nucleotide substitution in the second glycine codon at the tip of the gp120 V3 loop (GG (C) under ba r). This substitution was seen in 17 of 20 (85%) viruses of IVDUs in N orthern Europe, in none of 41 homosexual men in either Europe or the U nited States, and in 5 of 11 (45%) U.S. IVDUs sequences analyzed, Subs equent phylogenetic and multivariate principal coordinate (PCOORD) ana lyses showed that 16 of 20 (80%) of the Northern European IVDU sequenc es clustered together with the 5 U.S. IVDU sequences carrying the GG ( C) under bar substitution and away from the sequences of homosexual me n from either Europe or the United States, Taken together with the hig her level of heterogeneity of U.S. IVDU sequences compared to the Dutc h IVDU sequences taken at the same time, these data present suggestive evidence for a U.S. instead of a European origin of the AIDS epidemic among Northern European IVDUs.