@article {44182,
	title = {Molecular investigation of a new HIV-1 outbreak among people who inject drugs in Greece: evidence for a dense network of HIV-1 transmission},
	journal = {Sex Transm InfectSex Transm InfectSex Transm Infect},
	year = {2025},
	note = {1472-3263Kostaki, Evangelia GeorgiaOrcid: 0000-0002-3346-0930Papadimitriou, EvangeliaChatzopoulou, FaniRoussos, SotiriosTsirogianni, EfrosiniPsichogiou, MinaGoulis, IoannisKalamitsis, GeorgiosKefala, Anastasia MariaSkoura, LemoniaChrysanthidis, TheofilosMetallidis, SymeonTsiara, ChrysaParaskeva, DimitraMagiorkinis, GkikasBeloukas, ApostolosOrcid: 0000-0001-5639-0528Hatzakis, AngelosSypsa, VanaChatzidimitriou, DimitriosParaskevis, DimitriosJournal ArticleEnglandSex Transm Infect. 2025 May 28:sextrans-2024-056452. doi: 10.1136/sextrans-2024-056452.},
	month = {May 28},
	edition = {2025/05/30},
	abstract = {OBJECTIVES: Αn HIV-1 outbreak was identified among people who inject drugs (PWID) in Thessaloniki, Greece, during 2019-2021. We aimed to investigate the characteristics of this outbreak by means of molecular epidemiology. METHODS: We analysed 57 sequences from PWID sampled in Thessaloniki during 2019-2023. Phylogenetic trees were inferred using all subtype A sequences from PWID sampled since 1999 in Greece and reference sequences (n=4824). Phylodynamic analysis was performed using the Bayesian birth-death skyline serial model. RESULTS: Most of the 57 study sequences belonged to sub-subtypes A6 (49, 86\%) and A1 (4, 7\%). Phylogenetic analysis revealed that two (50\%) A1 sequences clustered together and 47 (95.9\%) A6 sequences fell within three PWID-specific phylogenetic clusters. The 99.6\% and 77.9\% of pairwise genetic distances within the largest and second largest PWID clusters were lower than 0.015 substitutions/site. Using a more stringent threshold (0.0015 substitutions/site), we identified five networks of sequences from PWID infected within 1 year. The effective reproduction number (R(e)) started to increase at the beginning of 2019 and remained high almost until the end of 2021. The estimated time from HIV-1 infection to diagnosis showed an increasing trend during 2020-2023 (p<0.001). CONCLUSIONS: The regional clustering of the PWID sequences and their low genetic divergence confirm its local spreading and the recent nature of the outbreak. Using a stringent genetic distance threshold, we showed that HIV-1 transmission occurred among large groups of PWID. The time of epidemic growth coincided with the time of the initial identification, and HIV-1 transmission continued at high rates until 2021.},
	keywords = {effective reproduction number, HIV-1, molecular epidemiology, outbreak, people who inject drugs, phylogenetic analysis},
	isbn = {1368-4973},
	author = {Kostaki, E. G. and Papadimitriou, E. and Chatzopoulou, F. and Roussos, S. and Tsirogianni, E. and Psichogiou, M and Goulis, I. and Kalamitsis, G. and Kefala, A. M. and Skoura, L. and Chrysanthidis, T. and Metallidis, S. and Tsiara, C and Paraskeva, D. and Magiorkinis, G and Beloukas, A. and Hatzakis, A and Sypsa, V and Chatzidimitriou, D. and Paraskevis, D}
}
