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The circulation of non-B subtypes in HIV-1 positive patients in the Brescia province (Northern Italy)
G. Lapadula1, I. Izzo2, G. Brindicci3, G. Labbate2, F. Gargiulo2, A. Calabresi2, E. Quiros-Roldan2, G. Carosi2, L. Monno3, N. Manca2, C. Torti2
1San Gerardo Hospital, Monza, Italy, 2University of Brescia, Brescia, Italy, 3University of Bari, Bari, Italy
Background: Emergence of non-B subtypes and circulating recombinant forms (CRF) is now evident in the HIV epidemics in Western Countries. We aimed at assessing the prevalence of non-B subtypes, their penetration into the Italian population and possible circulation among patients of different ethnicities and different modes of HIV transmission.
Methods: All HIV-positive patients who underwent >/= 1 genotypic resistance testing between 2002 and 2006 were selected. Subtyping was obtained using the REGA HIV subtyping tool. All sequences were analyzed for phylogenetic relationships.
Results: 287/1563 patients (18.4%) were infected with a non-B subtype. Among Italian patients, the most frequent subtypes were B (1184/1314=90.1%) and F (4%). F subtype was also one of the two most frequent in patients from South-America (9/66=13.6%) after B subtype (63.6%), while, among patients of African origin, CRF02_AG (67/122=54.9%) and G (12.3%) were the most frequent subtypes. HIV-1 non-B infections in Italians were mostly correlated with heterosexual risk for HIV acquisition (73.6%, 75% and 100% of subtypes F, C and CRF02_AG, respectively) or homosexual intercourses (15.1%, 16.7% and 0%, respectively). Phylogenetic relationship between F subtypes in Italian and Brazilian patients was found apart from 1 HIV isolate which was related to isolates circulating in Romania; moreover, recombinant B_F subtypes emerged in the latest years and were equally distributed in Italian and Brazilian patients. C subtypes in Italians were phylogenetically related to subtypes circulating in Brazil.
Conclusions: HIV-1 epidemic is evolving in Italy, with increasing emergence of diverse non-B subtypes. The transmission of these strains is occurring mainly through heterosexual intercourses. The distribution of HIV-1 non-B subtypes in Italian patients reflects that in South Americans, suggesting a transmission chain of the infection between these two groups of patients, a rather established circulation within the Italian population and the need of targeted prevention strategies.
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