Viruses Previously Classified as CRF146_BC, a Circulating Recombinant Form of HIV-1 Recently Reported in Brazil, Represent Different Recombinant Forms, One of Which Is Circulating in Spain.

Donoso, AnaMoreno-Lorenzo, MariaDelgado, ElenaCañada-Garcia, Javier EnriqueIribarren, José AntonioSalicio, YolandaBenito, SoniaLorente-Sorolla, ClaraDel Romero-Guerrero, JorgeBaza-Caraciolo, María BegoñaDíez-Fuertes, FranciscoZamarrón, PilarTéllez, RaquelMiqueleiz, AnaGómez-González, CarmenCortizo, SandraMorano, LuisThomson, Michael M2026-01-272026-01-272026-01-12Donoso A, Moreno-Lorenzo M, Delgado E, Cañada-García JE, Iribarren JA, Salicio Y, Benito S, Lorente-Sorolla C, Del Romero-Guerrero J, Baza-Caraciolo MB, et al. Viruses Previously Classified as CRF146_BC, a Circulating Recombinant Form of HIV-1 Recently Reported in Brazil, Represent Different Recombinant Forms, One of Which Is Circulating in Spain. Viruses. 2026; 18(1):101. https://doi.org/10.3390/v18010101.1999-4915https://hdl.handle.net/20.500.12105/27183The sequences newly obtained in the study are available in GenBank under accessions PX661829-PX661845.Circulating recombinant forms (CRFs) are important components of the HIV-1 pandemic. Previous studies have reported the propagation of diverse HIV-1 CRFs of South American origin in Europe. Here, through protease-reverse transcriptase (Pr-RT) and integrase sequence analyses, we identify a Spanish cluster (BC3) branching with a Brazilian virus (10BR_RJ009) previously classified as CRF146_BC. In Pr-RT, BC3 comprised 14 viruses and was nested within a larger cluster, comprising 22 Brazilian viruses and 1 Spanish virus branching outside of BC3. Near full-length genome analyses of five BC3 viruses revealed mosaic structures identical to 10BR_RJ009, with two breakpoints delimiting a ~0.3 kb subtype B fragment within an otherwise subtype C genome. Two other Brazilian viruses previously classified as CRF146_BC (10BR_RJ039 and 01_BR_RGS69) had one and two additional short subtype B fragments, respectively, and failed to group with the 10BR_RJ009/BC3 cluster in subtype C fragments. Based on these results, we contend that 10BR_RJ009 and BC3 viruses, but not 10BR_RJ039 and 01_BR_RGS69, should be classified as CRF146_BC. Bayesian analyses estimated the CRF146_BC emergence in Brazil to be around 1999 and its introduction in Europe around 2011. CRF146_BC is the 10th CRF of South American origin reported to circulate in Europe, reflecting the relationship between South American and European HIV-1 epidemics.engVoRhttp://creativecommons.org/licenses/by/4.0/HIV-1Circulating recombinant formsUnique recombinant formsGenetic diversityPhylogenyPhylodynamicsViruses Previously Classified as CRF146_BC, a Circulating Recombinant Form of HIV-1 Recently Reported in Brazil, Represent Different Recombinant Forms, One of Which Is Circulating in Spain.Attribution 4.0 International18110110.3390/v18010101Virusesopen access