Epidemiological and phylogenetic analysis for non-B subtypes of human immunodeficiency virus type 1 in Busan, Korea.

Recent data on non-B subtypes' epidemiology among patients infected with human immunodeficiency virus-1 (HIV-1) in Korea are lacking. We aimed to assess the changing trends in the epidemiology of non-B subtypes of HIV-1 in Korea using phyloepidemiological analyses. We analyzed the demographic records and sequencing data obtained from genotypic drug resistance tests between 2005 and 2019 from 517 patients infected with HIV attending a tertiary care hospital in Busan, Korea. Subtyping and phylogenetic analyses with reference sequences were performed. Additionally, transmission clusters were identified via maximum-likelihood trees. Non-B subtypes accounted for 21.3% of the 517 sequences. CRF01_AE (52.7%) was the most common non-B subtype, followed by CRF02_AG (16.4%), A1 (11.8%), and C (5.5%). The prevalence of non-B subtypes decreased from 36.4 to 13.4% by 2009, while it increased to 27.4% between 2015 and 2019. Among patients with non-B subtypes, the proportion of overseas sailors decreased from 66.7 to 7.5%; contrarily, the proportion of men-who-have-sex-with-men (MSM) increased from 0 to 46.9% over the study period. We identified 8 transmission clusters involving non-B subtypes, with sizes ranging from 2 to 4 patients, including 3 clusters containing MSM. Our results highlight the changes in the epidemiological trends of non-B subtypes of HIV-1 in Korea.