Phylogenetic analysis provides evidence of interactions between Italian heterosexual and South American homosexual males as the main source of national HIV-1 subtype C epidemics.
The HIV-1 clade C is prevalent worldwide and spread from Africa to South East Asia and South America early in the course of the epidemic. As a consequence of migration waves about 13% of the Italian HIV-1 epidemic is sustained by this clade. Two hundred fifty-four C pol sequences from the Italian ARCA database collected during 1997-2011 were analyzed. Epidemiological networks and geographical fluxes were identified through phylogeny using Bayesian approaches. Patients' country of origin was Italy, Africa, South America, and South East Asia for 44.9%, 23.6%, 4.7%, and 1.6%, respectively. Heterosexuals and men having sex with men accounted for 83.2% and 16.8%, respectively. Modality of infection was distributed differently: heterosexuals were largely prevalent among Italians (84.1%) and Africans (95.3%), while men having sex with men predominated among South Americans (66.7%). Eight significant clusters encompassing 111 patients (43.7%) were identified. Comparison between clustering and non-clustering patients indicated significant differences in country of origin, modality of infection and gender. Men having sex with men were associated to a higher probability to be included in networks (70% for men having sex with men vs. 30.3% for heterosexuals). Phylogeography highlighted two significant groups. One contained Indian strains and the second encompassed South Americans and almost all Italian strains. Phylogeography indicated that the spread of C subtype among Italians is related to South American variant. Although Italian patients mainly reported themselves as heterosexuals, homo-bisexual contacts were likely their source of infection. Phylogenetic monitoring is warranted to guide public health interventions aimed at controlling HIV infection.
Department of Biomedical and Clinical Science, Infectious Diseases and Immunopathology Section, 'L. Sacco' Hospital, University of Milan, Milan, Italy.
Alessia
A
Lai
Giorgio
G
Bozzi
Marco
M
Franzetti
Francesca
F
Binda
Francesco R
FR
Simonetti
Valeria
V
Micheli
Paola
P
Meraviglia
Paola
P
Corsi
Patrizia
P
Bagnarelli
Andrea
A
De Luca
Massimo
M
Ciccozzi
Gianguglielmo
G
Zehender
Maurizio
M
Zazzi
Claudia
C
Balotta
D000328:Adult; D000818:Animals; D016000:Cluster Analysis; D058872:Epidemics; D005260:Female; D005838:Genotype; D015658:HIV Infections / Q000453:epidemiology* / Q000635:transmission* / Q000821:virology; D015497:HIV-1 / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D020010:Heterosexuality; D006716:Homosexuality; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D058974:Phylogeography; D013020:South America / Q000453:epidemiology; D054302:pol Gene Products, Human Immunodeficiency Virus / Q000235:genetics
D054302:pol Gene Products, Human Immunodeficiency Virus
HIV-1 C subtype; Italian epidemiological networks; phylogeographic analysis