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.
Highlights
HIV-1 is characterized by a high evolutionary rate that led to the establishment of different viral lineages
It is further divided into nine subtypes (A, B, C, D, F, G, H, J and K), six sub-subtypes (A1, A2, A3, A4, F1 and F2), an increasing number of Circulating Recombinant Forms (CRFs) and an undetermined number of Unique Recombinant Forms (URFs) [1]
Characteristics of Population We studied 343 HIV-1 F1 infected patients with sequence data obtained from 1998 to 2009
Summary
HIV-1 is characterized by a high evolutionary rate that led to the establishment of different viral lineages. Group M is the most widespread group representing the main source of the HIV/AIDS pandemic. As a consequence of migratory waves from low-middle income areas, non-B variants entered and circulates in almost all previously B-restricted European countries [2,3,4,5,6]. The prevalence of non-B subtypes grew from 2.6% in 1985–1992 to 18.9% in 1993–2008. Among these non-B isolates, subtype F1 is the most frequent variant (44.3%) among European subjects followed at 50 Italian clinical Centers [8]
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