Changing patterns in HIV‐1 non‐B clade prevalence and diversity in Italy over three decades^*

Abstract

BackgroundHIV-1 non-B subtypes have recently entered Western Europe following immigration from other regions. The distribution of non-B clades and their association with demographic factors, over the entire course of the HIV-1 epidemic, have not been fully investigated in Italy. MethodsWe carried out a phylogenetic analysis of HIV-1 pol sequences derived from 3670 patients followed at 50 Italian clinical centres over nearly three decades. ResultsOverall, 417 patients (11.4%) carried non-B subtypes. The prevalence of non-B strains increased from 2.6% in 1980 -1992 to 18.9% in 1993) in a subset of 2479 subjects with a known year of diagnosis. A multivariate analysis on a subset of 1364 patients for whom relevant demographic data were available indicated that African ethnicity, heterosexual route of infection and year of diagnosis were independently associated with non-B HIV-1 infection (P 0.0001). All pure subtypes, except for clade K, and seven circulating recombinant forms were detected, accounting for 56.6 and 34.1% of the non-B infections, respectively. The F1 subtype was the most prevalent non-B clade among Europeans and was acquired heterosexually in half of this patient population. Unique recombinant forms accounted for 9.4% of the non-B sequences and showed a B/F1 recombination pattern in one-third of cases. ConclusionsThe circulation of non-B clades has significantly increased in Italy in association with demographic changes. Spread of the F1 subtype and B/F recombinants appears to predominate, which may result in a redistribution of the relative proportions of the different strains, and this could lead to overlapping epidemics. Thus, the HIV-1 landscape in Italy may in future be distinct from that of the rest of Europe. IntroductionNine discrete lineages of group M HIV-1 (A-D, F-H, J and K) have differentiated during the global pandemic as a result of massive virus replication, the very high error rate of reverse transcriptase (RT) and the selective pressure exerted by the immune system. The highly recombinogenic activity of HIV-1 RT has added further complexity to the global diversity of HIV-1 as 43 circulating recombinant forms (CRFs) have already been characterized and a number of unique recombinant forms (URFs) have been identified world-wide [1][2][3]. Most subtypes and CRFs were originally restricted to specific geographical regions or populations, but their distribution is constantly evolving [4]. In order to monitor the evolution of the global pandemic, it is convenient and effective to assign viral clades, which allow evaluation of the local epidemiological trends that result from social changes and migration flows. [6][7][8][9][10][11][12][13]. The recent epidemiology of HIV-1 infection in Western European countries with large immigrant communities has been characterized by increasing genetic diversity and a marked rise in non-B subtype strains among newly diagnosed individuals [14][15][16][17]. It has been assumed that most non-B subtype infections in Western Europe are linked to migration ...

Dynamics and molecular evolution of HIV-1 strains in Sicily among antiretroviral naïve patients

“…Brazil, the Caribbean, and Thailand) could likely be responsible for the entry of an array of group M subtypes into formerly subtype B-restricted geographic areas and, consequently, contributing for the changing profile of the local HIV epidemiology in host countries (Rice et al, 2012). As similarly reported in other studies in Italy (Lai et al, 2010) and elsewhere (Hawke et al, 2012;von Wyl et al, 2011), in the present paper, the totality of non-B infections among immigrant subjects correlate to heterosexual transmission, while non-B infections in homosexual individuals were exclusively found in Italian-born patients. Of note, native Italians who were infected with HIV-1 non-B strains mainly harboured URFs while known CRFs/subtypes were found only in a minority group of subjects.…”

“…The present work confirms CRF02_AG as the prevalent circulating recombinant form in our region, as well as in several European countries (González-Alba et al, 2011;von Wyl et al, 2011;Yebra et al, 2012), in contrast to that observed in the northern part of Italy where subtype F1 is the most prevalent non-B clade (Lai et al, 2010), mirroring the extensive influx of immigrants from Romania, an European country with a massive prevalence of subtype F1 HIV-1 infections .…”

“…In this regard, recent molecular epidemiology studies conducted in Western Europe including Italy, either in ARV-treated or -untreated patients, reported the circulation of several non-B subtypes and CRFs together with a clear increasing trend over time (Buonaguro et al, 2002;Lai et al, 2010;Monno et al, 2012Monno et al, , 2005Tramuto et al, 2007Tramuto et al, , 2004.…”

Transmission of Resistant HIV Type 1 Variants and Epidemiological Chains in Italian Newly Diagnosed Individuals

“…These findings are in agreement with those reported in several European studies where limited initiatives are taken to prevent the spread of HIV-1 infection, leading to a large proportion of individuals unaware that they are infected, and migration flows that continue to occur from HIV-1 endemic areas. [18][19][20] The incomplete effect of ARVs at the population level may account for the considerable levels of primary resistance due to some extent to patients experiencing therapy failure. However, the decrease of seroconversions may be explained by the new potent drugs that are used in first line regimens at present.…”

Near Full-Length Sequence Analysis of HIV Type 1 BF Recombinants from Italy

“…A recent survey on the whole HIV-1 sequence database at the HML revealed 85% of subtype B sequences and 15% of non-B subtypes, mainly CRF02_AG, F1, C, and A1, based on the pol region. 3 In some cases, assignments of subtype based on the pol and env regions were not in agreement. 4 These discrepancies mostly involved subtypes B and F1.…”