title: HIV-1 subtype F1 epidemiological networks among Italian heterosexual males are associated with introduction events from South America.
abstract: About 40% of the Italian HIV-1 epidemic due to non-B variants is sustained by F1 clade, which circulates at high prevalence in South America and Eastern Europe. Aim of this study was to define clade F1 origin, population dynamics and epidemiological networks through phylogenetic approaches. We analyzed pol sequences of 343 patients carrying F1 subtype stored in the ARCA database from 1998 to 2009. Citizenship of patients was as follows: 72.6% Italians, 9.3% South Americans and 7.3% Rumanians. Heterosexuals, Homo-bisexuals, Intravenous Drug Users accounted for 58.1%, 24.0% and 8.8% of patients, respectively. Phylogenetic analysis indicated that 70% of sequences clustered in 27 transmission networks. Two distinct groups were identified; the first clade, encompassing 56 sequences, included all Rumanian patients. The second group involved the remaining clusters and included 10 South American Homo-bisexuals in 9 distinct clusters. Heterosexual modality of infection was significantly associated with the probability to be detected in transmission networks. Heterosexuals were prevalent either among Italians (67.2%) or Rumanians (50%); by contrast, Homo-bisexuals accounted for 71.4% of South Americans. Among patients with resistant strains the proportion of clustering sequences was 57.1%, involving 14 clusters (51.8%). Resistance in clusters tended to be higher in South Americans (28.6%) compared to Italian (17.7%) and Rumanian patients (14.3%). A striking proportion of epidemiological networks could be identified in heterosexuals carrying F1 subtype residing in Italy. Italian Heterosexual males predominated within epidemiological clusters while foreign patients were mainly Heterosexual Rumanians, both males and females, and South American Homo-bisexuals. Tree topology suggested that F1 variant from South America gave rise to the Italian F1 epidemic through multiple introduction events. The contact tracing also revealed an unexpected burden of resistance in epidemiological clusters underlying the need of public interventions to limit the spread of non-B subtypes and transmitted drug resistance.
authors.affiliation: Department of Biomedical and Clinical Science, Infectious Diseases and Immunopathology Section, L Sacco' Hospital, University of Milan, Milan, Italy. alessia.lai@unimi.it
authors.forename: Alessia
authors.initials: A
authors.lastname: Lai
authors.forename: Francesco R
authors.initials: FR
authors.lastname: Simonetti
authors.forename: Gianguglielmo
authors.initials: G
authors.lastname: Zehender
authors.forename: Andrea
authors.initials: A
authors.lastname: De Luca
authors.forename: Valeria
authors.initials: V
authors.lastname: Micheli
authors.forename: Paola
authors.initials: P
authors.lastname: Meraviglia
authors.forename: Paola
authors.initials: P
authors.lastname: Corsi
authors.forename: Patrizia
authors.initials: P
authors.lastname: Bagnarelli
authors.forename: Paolo
authors.initials: P
authors.lastname: Almi
authors.forename: Alessia
authors.initials: A
authors.lastname: Zoncada
authors.forename: Stefania
authors.initials: S
authors.lastname: Paolucci
authors.forename: Angela
authors.initials: A
authors.lastname: Gonnelli
authors.forename: Grazia
authors.initials: G
authors.lastname: Colao
authors.forename: Danilo
authors.initials: D
authors.lastname: Tacconi
authors.forename: Marco
authors.initials: M
authors.lastname: Franzetti
authors.forename: Massimo
authors.initials: M
authors.lastname: Ciccozzi
authors.forename: Maurizio
authors.initials: M
authors.lastname: Zazzi
authors.forename: Claudia
authors.initials: C
authors.lastname: Balotta
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D016000:Cluster Analysis; D005061:Europe, Eastern / Q000453:epidemiology; D005260:Female; D015658:HIV Infections / Q000453:epidemiology* / Q000635:transmission; D015497:HIV-1 / Q000145:classification / Q000235:genetics*; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D010802:Phylogeny; D012307:Risk Factors; D019529:Sexuality; D013020:South America / Q000453:epidemiology; D044465:White People; D055815:Young Adult