RESUMO
Specific features of human immunodeficiency virus type 1 (HIV-1) transmission among injecting drug users were studied on HIV infection outbreak in Lysva, the Perm region. During the period from November 1998 to March 2000, 32 injecting drug users infected with the subtype A HIV-1 variant originating from the same source, were found in this town. To understand the role of the CCR5 delta 32 mutation in parenteral transmission of HIV-1 the distribution of the mutant CCR5 delta 32 allele in HIV-infected and in non-infected but HIV-exposed drug users (n = 74) was analysed. The percentage of the homozygous CCR5 delta 32 genotype among HIV-exposed individuals (4/74, 5.4%) was significantly (p < 0.05) higher than the analogous rate for healthy blood donors in Russia (1/163, 0.6%). Thus, the homozygosity for this mutant allele confers a high resistance level to HIV even in parenteral transmission.