The number of non-B subtype HIV-1 infections in Europe has been increasing even though major regional differences have been observed. This trend was investigated in northwestern Poland using sequence and epidemiological data from a cohort of 102 HIV-1-infected patients from Szczecin, Poland. HIV-1 subtypes were defined by phylogenetic analysis of viral reverse transcriptase- and protease-partial coding regions, and results were compared with online subtyping by Standford and REGA tools. Subtype analysis using on-line subtyping methods produced varying results if compared to phylogenesis, with concordant variant assignment obtained for 98% (100/102) of sequences by Stanford and 85% (87/102) by REGA. In the population studied, non-B subtype infections comprised 21% of the infections and consisted of subtype D (57%, n = 12), CRF01_AE (19%, n = 4), A and C clades (9.5%, n = 2), and the CRF13_cpx recombinant isolate (4.8%, n = 1). Patients carrying non-B subtypes were predominantly heterosexuals with high percentage (57%) of women observed in the group. All HIV-1 non-B women were Caucasian with majority (83%) of infections acquired in Poland; however, among 12 travelers included in the study a higher proportion of non-B infections was noted (50%, P = 0.01). Moreover, lower baseline lymphocyte CD4 counts (P = 0.01), higher baseline HIV-1 viremia (P = 0.08), and a more advanced stage of the disease (P = 0.03) were observed among individuals infected with non-B subtypes. The data indicated that the proportion of HIV-1 non-B subtype infections was higher than previously reported in Poland consisting of a high subtype D prevalence. Furthermore, subtype D transmission occurred primarily between heterosexual Caucasian individuals from this region.
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