title: Population dynamics of HIV-1 subtype B in a cohort of men-having-sex-with-men in Rome, Italy.
abstract: A recent increase in HIV diagnoses among men-having-sex-with-men (MSM) has been shown by surveillance data from Europe and Italy, and new approaches to inferring viral population dynamics from heterochronously sampled gene sequences have been developed. The aim of this study was to reconstruct the epidemiological history of HIV-1 subtype B in a homogeneous group of Italian MSM using a coalescent-based Bayesian framework. A total of 125 HIV-1 subtype B pol sequences were analyzed using Bayesian methods and a relaxed molecular clock to reconstruct their dated phylogeny and estimate population dynamics. At least 10 epidemiological clusters of 3-9 isolates were identified: half including the largest clades originated in the early 1990s and the other half radiated from 1999. Demographic analysis showed that the HIV epidemic grew in accordance with a logistic model characterized by a rapid exponential increase in the effective number of infections (r = 1.54 year) starting from the early 1980s and reaching a plateau 10 years later. Our data suggest that the HIV B epidemic entered our MSM population through multiple transmission chains about 20 years later than in other Western European country. Epidemiological clusters originating in the early 2000s suggest a recent re-emergence of HIV in Italian MSM.
authors: Department of Clinical Sciences, L. Sacco, University of Milan, Milan, Italy. gianguglielmo.zehender@unimi.it
authors: Gianguglielmo
authors: G
authors: Zehender
authors: Erika
authors: E
authors: Ebranati
authors: Alessia
authors: A
authors: Lai
authors: Maria Mercedes
authors: MM
authors: Santoro
authors: Claudia
authors: C
authors: Alteri
authors: Massimo
authors: M
authors: Giuliani
authors: Guido
authors: G
authors: Palamara
authors: Carlo Federico
authors: CF
authors: Perno
authors: Massimo
authors: M
authors: Galli
authors: Alessandra
authors: A
authors: Lo Presti
authors: Massimo
authors: M
authors: Ciccozzi
mesh_terms: D001499:Bayes Theorem; D015331:Cohort Studies; D015658:HIV Infections / Q000453:epidemiology / Q000821:virology*; D015497:HIV-1 / Q000235:genetics; D018451:Homosexuality, Male; D006801:Humans; D008297:Male; D010802:Phylogeny; D011157:Population Dynamics; D012384:Rome / Q000453:epidemiology; D013997:Time Factors