AUTHOR=Pingarilho Marta , Pimentel Victor , Miranda Mafalda N. S. , Silva Ana Rita , Diniz António , Ascenção Bianca Branco , Piñeiro Carmela , Koch Carmo , Rodrigues Catarina , Caldas Cátia , Morais Célia , Faria Domitília , da Silva Elisabete Gomes , Teófilo Eugénio , Monteiro Fátima , Roxo Fausto , Maltez Fernando , Rodrigues Fernando , Gaião Guilhermina , Ramos Helena , Costa Inês , Germano Isabel , Simões Joana , Oliveira Joaquim , Ferreira José , Poças José , da Cunha José Saraiva , Soares Jorge , Henriques Júlia , Mansinho Kamal , Pedro Liliana , Aleixo Maria João , Gonçalves Maria João , Manata Maria José , Mouro Margarida , Serrado Margarida , Caixeiro Micaela , Marques Nuno , Costa Olga , Pacheco Patrícia , Proença Paula , Rodrigues Paulo , Pinho Raquel , Tavares Raquel , de Abreu Ricardo Correia , Côrte-Real Rita , Serrão Rosário , Castro Rui Sarmento e , Nunes Sofia , Faria Telo , Baptista Teresa , Martins Maria Rosário O. , Gomes Perpétua , Mendão Luís , Simões Daniel , Abecasis Ana TITLE=HIV-1-Transmitted Drug Resistance and Transmission Clusters in Newly Diagnosed Patients in Portugal Between 2014 and 2019 JOURNAL=Frontiers in Microbiology VOLUME=Volume 13 - 2022 YEAR=2022 URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.823208 DOI=10.3389/fmicb.2022.823208 ISSN=1664-302X ABSTRACT=Objective: To describe and analyze Transmitted Drug Resistance (TDR) between 2014 and 2019 in newly infected HIV-1 patients in Portugal and to characterize its transmission networks. Methods: Clinical, socio-epidemiological and risk behavior data was collected from 820 newly diagnosed patients in Portugal between September 2014 and December 2019. Sequences obtained from drug resistance testing were used for subtyping, TDR determination and transmission clusters (TC) analyses. Results: In Portugal, the overall prevalence of TDR between 2014 and 2019 was 11.0%. TDR presented a decreasing trend from 16.7% in 2014 to 9.2% in 2016 (pfor-trend = 0.114). Multivariate analysis indicated that TDR was significantly associated with transmission route (MSM presented lower probability of presenting TDR when compared to heterosexual contact) and with subtype (subtype C presented significantly more TDR when compared to subtype B). TC analysis corroborated that the heterosexual risk group presented a higher proportion of TDR in TCs when compared to MSMs. Among subtype A1, heterosexuals reached 16.6% of TDR, followed by 14.2% in patients infected with subtype B and 9.4% in patients infected with subtype G. Conclusion: Our molecular epidemiology approach indicates that the HIV-1 epidemic in Portugal is changing among risk group populations, with heterosexuals showing increasing levels of HIV-1 transmission and of TDR. Prevention measures for this subpopulation should be reinforced