The spread of HIV-1 subtypes varies considerably both worldwide and within Europe, with non-B variants commonly found across various exposure groups. This study aimed to analyse the distribution and temporal trends in HIV-1 subtype variability across Poland. For analysis of the subtype distribution, 1219 partial pol sequences obtained from patients followed up in 9 of 17 Polish HIV treatment centres were used. Subtyping was inferred using the maximum likelihood method; recombination was assessed using the bootscanning and jumping profile hidden Markov model methods. Subtype B dominated in the studied group (n=1059, 86.9%); in 160 (13.1%) sequences, non-B variants were present [A1 (n=63, 5.2%), D (n=43, 3.5%), C (n=22, 1.8%), and F1 (n=2, 0.2%)]. In 25 (2.1%) cases circulating recombinant forms (CRFs) were found. Five A1 variants (0.4%) were unique AB recombinant forms (URF) not previously identified in Poland. Non-B clades were notably more common among females (n=73, 45.6%, p<0.001) and heterosexual individuals (n=103, 66.5%, p<0.001) and less frequent among men who have sex with men (MSM) (n=27, 17.42%, p<0.001). HIV-1 viral load at diagnosis was higher among non-B cases [median: 5.0 (IQR: 4.4-5.6)] vs. [median: 4.8 (IQR: 4.3-5.4) log copies/ml for subtype B (p<0.001)] with a lower CD4(+) lymphocyte count at baseline [median: 248 (IQR: 75-503) for non-B vs. median: 320 (IQR: 125-497) cells/μl for subtype B; p<0.001]. The frequency of the non-B subtypes proved stable from 2008 (11.5%) to 2014 (8.0%) [OR: 0.95 (95% CI: 0.84-1.07), p=0.4], with no temporal differences for exposure groups, gender, age and AIDS. Despite the predominance of subtype B, the variability of HIV in Poland is notable; both CRFs and URFs are present in the analysed population. Non-B variants are associated with heterosexual transmission, more advanced HIV disease and have stable temporal frequencies.
Keywords: HIV subtypes; Phylogeny; Recombination.
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