Durability of Humoral Responses after the Second Dose of mRNA BNT162b2 Vaccine in Residents of a Long Term Care Facility.

Residents of long-term care facilities (LTCFs) have been dramatically hit by the COVID-19 pandemic on a global scale as older age and comorbidities pose an increased risk of severe disease and death. The aim of the study was to assess the quantity and durability of specific antibody responses to SARS-CoV-2 after the first cycle (two doses) of BNT162b2 vaccine. To achieve this, SARS-CoV-2 Spike-specific IgG (S-IgG) titers was evaluated in 432 residents of the largest Italian LTCF at months 2 and 6 after vaccination. By stratifying levels of humoral responses as high, medium, low and null, we did not find any difference when comparing the two time points; however, the median levels of antibodies halved overtime. As positive nucleocapsid serology was associated with a reduced risk of a suboptimal response at both time points, we conducted separate analyses accordingly. In subjects with positive serology, the median level of anti-S IgG slightly increased at the second time point, while a significant reduction was observed in patients without previous exposure to the virus. At month 6, diabetes alone was associated with an increased risk of impaired response. Our data provide additional insights into the longitudinal dynamics of the immune response to BNT162b2 vaccination in the elderly, highlighting the need for SARS-CoV-2 antibody monitoring following third-dose administration.

Sero-survey on long-term care facility residents reveals increased risk of sub-optimal antibody response to BNT162b2: implications for breakthrough prevention.

BACKGROUND: The impact of coronavirus disease 2019 (COVID-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) on residents of long-term care facilities (LTCFs) has been dramatic on global scale as older age and comorbidities pose an increased risk of severe disease and death. METHODS: Aim of this study was to evaluate SARS-CoV-2 Spike-specific IgG (S-IgG) antibody titers in 478 residents and 649 health care workers of a large Italian long-term care facility two months after complete vaccination with BNT162b2. Associations among resident-related factors and predictors of humoral response were investigated. RESULTS: By stratifying levels of humoral responses, we found that 62.1%, 21.6%, 12.1% and 4.2% of residents had high (>1,000 BAU/ml), medium (101-1,000), low (1-100) and null (<1 BAU/mL) S-IgG titers, respectively. Residents with documented previous COVID-19 and those with SARS-CoV-2 nucleocapsid-specific IgG (N-IgG) positive serology showed higher level of serological response, while significant associations were observed for cancer with suboptimal response (p = 0.005) and the administration of corticosteroid for suboptimal response (p = 0.028) and a null one (p = 0.039). According to multivariate logistic regression, predictors of an increased risk of null response were advanced age (Odd ratio, OR: 2.630; Confidence interval, CI: 1.13-6.14; p = 0.025), corticosteroid therapy (OR: 4.964; CI: 1.06-23.52; p = 0.042) and diabetes mellitus (OR:3.415; CI:1.08-10.8; p = 0.037). In contrast, previous diagnosis of COVID-19 was strongly associated with a reduced risk of null response to vaccination (OR:0.126; CI:0.02-0.23; p < 0.001). CONCLUSIONS: SARS-CoV-2 specific antibodies in elderly individuals should be consider when deciding the need of a third dose of vaccine for prevention of reinfections in LTCFs despite the maintenance of barrier measures.

Marked decrease in acquired resistance to antiretrovirals in latest years in Italy.

OBJECTIVES: The aim of this study was to evaluate acquired drug resistance in Italy in the 2009-2018 period. METHODS: We analysed 3094 patients from the Italian ARCA database who had failed antiretroviral treatment and who had received a genotypic test after 6 months of treatment. Drug resistance mutations were identified using International AIDS Society (IAS)-USA tables and the Stanford HIVdb algorithm. The global burden of acquired resistance was calculated among all subjects with antiretroviral failure. Time trends and correlates of resistance were analysed using standard statistical tests. RESULTS: Patients of non-European origin and non-B subtypes increased significantly from 11.5% (103/896) to 19.2% (33/172) and from 13.1% (141/1079) to 23.8% (53/223), respectively, over time. Overall, 14.5% (448/3094), 12.1% (374/3094) and 37.8% (1169/3094) of patients failed first, second and later lines, respectively. According to both IAS and HIVdb, in the study period resistance to any class, nucleoside reverse inhibitor, non-nucleoside reverse inhibitor, and protease inhibitors (PIs) declined significantly. Integrase strand transfer inhibitor (INSTI) resistance declined significantly from 31% (36/116) to 20.8% (41/197) according to HIVdb but not to IAS. Divergent data were highlighted regarding the proportion of non-European patients carrying any, PI and INSTI resistance using IAS tables compared with the Stanford HIVdb algorithm, as the former failed to detect a decrease in resistance while the latter indicates a reduction of 1.6-, 5- and 1.8-fold resistance for such drug classes. In the multivariate analysis, the risk of resistance increased in patients with a larger number of treatment lines and higher viraemia and decreased in those starting therapy in the last biennium of the study. DISCUSSION: A marked reduction in drug resistance was observed over 10 years, compatible with higher genetic barrier and potency of new antiretrovirals. Nonetheless, concerns remain for subjects with non-B subtypes when using mutation lists instead of interpretation systems because of the extensive polymorphism of the protease region.

Molecular Tracing of SARS-CoV-2 in Italy in the First Three Months of the Epidemic.

The aim of this study is the characterization and genomic tracing by phylogenetic analyses of 59 new SARS-CoV-2 Italian isolates obtained from patients attending clinical centres in North and Central Italy until the end of April 2020. All but one of the newly-characterized genomes belonged to the lineage B.1, the most frequently identified in European countries, including Italy. Only a single sequence was found to belong to lineage B. A mean of 6 nucleotide substitutions per viral genome was observed, without significant differences between synonymous and non-synonymous mutations, indicating genetic drift as a major source for virus evolution. tMRCA estimation confirmed the probable origin of the epidemic between the end of January and the beginning of February with a rapid increase in the number of infections between the end of February and mid-March. Since early February, an effective reproduction number (Re) greater than 1 was estimated, which then increased reaching the peak of 2.3 in early March, confirming the circulation of the virus before the first COVID-19 cases were documented. Continuous use of state-of-the-art methods for molecular surveillance is warranted to trace virus circulation and evolution and inform effective prevention and containment of future SARS-CoV-2 outbreaks.

Genomic characterization and phylogenetic analysis of SARS-COV-2 in Italy.

This report describes the isolation, molecular characterization, and phylogenetic analysis of the first three complete genomes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) isolated from three patients involved in the first outbreak of COVID-19 in Lombardy, Italy. Early molecular epidemiological tracing suggests that SARS-CoV-2 was present in Italy weeks before the first reported cases of infection.

Contribution of transgender sex workers to the complexity of the HIV-1 epidemic in the metropolitan area of Milan.

OBJECTIVES: Transgender people are disproportionately affected by the HIV-1 epidemic. We evaluated the origin of HIV-1 variants carried by South American transgenders living in Milan by combining accurate phylogenetic methods and epidemiological data. METHODS: We collected 156 HIV-1 pol sequences obtained from transgender patients engaged in sex work (TSWs) followed between 1999 and 2015 at L. Sacco Hospital, Milan, Italy. Phylogenetic analyses were conducted by HIV-TRACE, MrBayes, MacClade and Beast programs. Reference sequences were retrieved from Los Alamos and local databases. Last negative testing or proxy data from clinical records of infected individuals were used to investigate the country of infection. RESULTS: Among South American TSWs, the most represented HIV-1 subtypes were B (70.5%), F1 (12.8%) and C (4.4%). Gene flow migrations of B subtype indicated significant fluxes from TSWs to Italians (21.3%) belonging to all risk groups (26.4% to heterosexuals (HEs), 18.9% to men who have sex with men (MSM), 15.1% to injecting drug users). The largest proportion of bidirectional fluxes were observed between Italians and TSWs (24.6%). For F1 subtype, bidirectional viral fluxes involved TSWs and Italians (7.1% and 14.3%), and a similar proportion of fluxes linked TSWs and Italian HEs or MSM (both 15.8%). Significant fluxes were detected from Italians to TSWs for subtype C involving both MSM (30%) and HEs (40%). Country of HIV-1 acquisition was identified for 72 subjects; overall, the largest proportion of patients with B subtype (73.5%) acquired HIV-1 infection in South America. CONCLUSIONS: Our results indicated that South American transgenders largely contribute to the heterogeneity of HIV-1 variants in our country. The high number of clusters based on all subtypes indicated numerous transmission chains in which TSWs were constantly intermixed with HEs and MSM. Our results strongly advocate interventions to facilitate prevention, diagnosis and HIV-1 care continuum among transgender people.

Earlier Initiation of Antiretroviral Treatment Coincides With an Initial Control of the HIV-1 Sub-Subtype F1 Outbreak Among Men-Having-Sex-With-Men in Flanders, Belgium.

Human immunodeficiency virus type 1 (HIV-1) non-B subtype infections occurred in Belgium since the 1980s, mainly amongst migrants and heterosexuals, whereas subtype B predominated in men-having-sex-with-men (MSM). In the last decade, the diagnosis of F1 sub-subtype in particular has increased substantially, which prompted us to perform a detailed reconstruction of its epidemiological history. To this purpose, the Belgian AIDS Reference Laboratories collected HIV-1 pol sequences from all sub-subtype F1-infected patients for whom genotypic drug resistance testing was requested as part of routine clinical follow-up. This data was complemented with HIV-1 pol sequences from countries with a high burden of F1 infections or a potential role in the global origin of sub-subtype F1. The molecular epidemiology of the Belgian subtype F1 epidemic was investigated using Bayesian phylogenetic inference and transmission dynamics were characterized based on birth-death models. F1 sequences were retained from 297 patients diagnosed and linked to care in Belgium between 1988 and 2015. Phylogenetic inference indicated that among the 297 Belgian F1 sequences, 191 belonged to a monophyletic group that mainly contained sequences from people likely infected in Belgium (OR 26.67, 95% CI 9.59-74.15), diagnosed in Flanders (OR 7.28, 95% CI 4.23-12.53), diagnosed at a recent stage of infection (OR 7.19, 95% CI 2.88-17.95) or declared to be MSM (OR 34.8, 95% CI 16.0-75.6). Together with a Spanish clade, this Belgian clade was embedded in the genetic diversity of Brazilian subtype F1 strains and most probably emerged after one or only a few migration events from Brazil to the European continent before 2002. The origin of the Belgian outbreak was dated back to 2002 (95% higher posterior density 2000-2004) and birth-death models suggested that its extensive growth had been controlled (Re < 1) by 2012, coinciding with a time period where delay in antiretroviral treatment initiation substantially declined. In conclusion, phylogenetic reconstruction of the Belgian HIV-1 sub-subtype F1 epidemic illustrates the introduction and substantial dissemination of viral strains in a geographically restricted risk group that was most likely controlled by effective treatment as prevention.

Local Epidemics Gone Viral: Evolution and Diffusion of the Italian HIV-1 Recombinant Form CRF60_BC.

The molecular epidemiology of HIV-1 in Italy is becoming increasingly complex, mainly due to the spread of non-B subtypes and the emergence of new recombinant forms. We previously characterized the outbreak of the first Italian circulating recombinant form (CRF60_BC), occurring among young MSM living in Apulia between the years 2009 and 2011. Here we show a 5-year follow-up surveillance to trace the evolution of CRF60_BC and to investigate its further spread in Italy. We collected additional sequences and clinical data from patients harboring CRF60_BC, enrolled at the Infectious Diseases Clinic of the University of Bari. In addition to the 24 previously identified sequences, we retrieved 27 CRF60_BC sequences from patients residing in Apulia, whose epidemiological and clinical features did not differ from those of the initial outbreak, i.e., the Italian origin, young age at HIV diagnosis (median: 24 years; range: 18-37), MSM risk factor (23/25, 92%) and recent infection (from 2008 to 2017). Sequence analysis revealed a growing overall nucleotide diversity, with few nucleotide changes that were fixed over time. Twenty-seven additional sequences were detected across Italy, spanning multiple distant regions. Using a BLAST search, we also identified a CRF60_BC sequence isolated in United Kingdom in 2013. Three patients harbored a unique second generation recombinant form in which CRF60_BC was one of the parental strains. Our data show that CRF60_BC gained epidemic importance, spreading among young MSM in multiple Italian regions and increasing its population size in few years, as the number of sequences identified so far has triplicated since our first report. The observed further divergence of CRF60_BC is likely due to evolutionary bottlenecks and host adaptation during transmission chains. Of note, we detected three second-generation recombinants, further supporting a widespread circulation of CRF60_BC and the increasing complexity of the HIV-1 epidemic in Italy.

A simple model of HIV epidemic in Italy: The role of the antiretroviral treatment.

In the present paper we propose a simple time-varying ODE model to describe the evolution of HIV epidemic in Italy. The model considers a single population of susceptibles, without distinction of high-risk groups within the general population, and accounts for the presence of immigration and emigration, modelling their effects on both the general demography and the dynamics of the infected subpopulations. To represent the intra-host disease progression, the untreated infected population is distributed over four compartments in cascade according to the CD4 counts. A further compartment is added to represent infected people under antiretroviral therapy. The per capita exit rate from treatment, due to voluntary interruption or failure of therapy, is assumed variable with time. The values of the model parameters not reported in the literature are assessed by fitting available epidemiological data over the decade 2003÷2012. Predictions until year 2025 are computed, enlightening the impact on the public health of the early initiation of the antiretroviral therapy. The benefits of this change in the treatment eligibility consist in reducing the HIV incidence rate, the rate of new AIDS cases, and the rate of death from AIDS. Analytical results about properties of the model in its time-invariant form are provided, in particular the global stability of the equilibrium points is established either in the absence and in the presence of infected among immigrants.

Origin and evolutionary dynamics of Hepatitis B virus (HBV) genotype E in Madagascar.

Africa is one of the endemic regions of HBV infection. In particular, genotype E is highly endemic in most of sub-Saharan Africa such as West African countries where it represents more than 90% of total infections. Madagascar, which is classified as a high endemic area for HBV and where the most prevalent genotype is E, might play a relevant role in the dispersion of this genotype due to its crucial position in the Indian Ocean. The aim of this study was to investigate the origin, population dynamics, and circulation of HBV-E genotype in Madagascar through high-resolution phylogenetic and phylodynamic approaches. The phylogenetic tree indicated that Malagasy isolates were intermixed and closely related with sequences mostly from West African countries. The Bayesian tree highlighted three statistically supported clusters of Malagasy strains which dated back to the years 1981 (95% HPD: 1971-1992), 1986 (95% HPD: 1974-1996), and 1989 (95% HPD: 1974-2001). Population dynamics analysis showed an exponential increase in the number of HBV-E infections approximately from the year 1975 until 2000s. The migration analysis was also performed and a dynamic pattern of gene flow was identified. In conclusion, this study confirms previous observation of HBV-E circulation in Africa and expands these findings at Madagascar demonstrating its recent introduction, and highlighting the role of the African countries in the spread of HBV-E genotype. Further studies on molecular epidemiology of HBV genotype E are needed to clarify the evolutionary history of this genotype.

The global spread of HIV-1 subtype B epidemic.

Human immunodeficiency virus type 1 (HIV-1) was discovered in the early 1980s when the virus had already established a pandemic. For at least three decades the epidemic in the Western World has been dominated by subtype B infections, as part of a sub-epidemic that traveled from Africa through Haiti to United States. However, the pattern of the subsequent spread still remains poorly understood. Here we analyze a large dataset of globally representative HIV-1 subtype B strains to map their spread around the world over the last 50years and describe significant spread patterns. We show that subtype B travelled from North America to Western Europe in different occasions, while Central/Eastern Europe remained isolated for the most part of the early epidemic. Looking with more detail in European countries we see that the United Kingdom, France and Switzerland exchanged viral isolates with non-European countries than with European ones. The observed pattern is likely to mirror geopolitical landmarks in the post-World War II era, namely the rise and the fall of the Iron Curtain and the European colonialism. In conclusion, HIV-1 spread through specific migration routes which are consistent with geopolitical factors that affected human activities during the last 50years, such as migration, tourism and trade. Our findings support the argument that epidemic control policies should be global and incorporate political and socioeconomic factors.

HIV-1 A1 Subtype Epidemic in Italy Originated from Africa and Eastern Europe and Shows a High Frequency of Transmission Chains Involving Intravenous Drug Users.

BACKGROUND: Subtype A accounts for only 12% of HIV-1 infections worldwide but predominates in Russia and Former Soviet Union countries of Eastern Europe. After an early propagation via heterosexual contacts, this variant spread explosively among intravenous drug users. A distinct A1 variant predominates in Greece and Albania, which penetrated directly from Africa. Clade A1 accounts for 12.5% of non-B subtypes in Italy, being the most frequent after F1 subtype. AIM: Aim of this study was to investigate the circulation of A1 subtype in Italy and trace its origin and diffusion through phylogenetic and phylodynamic approaches. RESULTS: The phylogenetic analysis of 113 A1 pol sequences included in the Italian ARCA database, indicated that 71 patients (62.8%) clustered within 5 clades. A higher probability to be detected in clusters was found for patients from Eastern Europe and Italy (88.9% and 60.4%, respectively) compared to those from Africa (20%) (p < .001). Higher proportions of clustering sequences were found in intravenous drug users with respect to heterosexuals (85.7% vs. 59.3%, p = .056) and in women with respect to men (81.4% vs. 53.2%, p < .006). Subtype A1 dated phylogeny indicated an East African origin around 1961. Phylogeographical reconstruction highlighted 3 significant groups. One involved East European and some Italian variants, the second encompassed some Italian and African strains, the latter included the majority of viruses carried by African and Italian subjects and all viral sequences from Albania and Greece. CONCLUSIONS: Subtype A1 originated in Central Africa and spread among East European countries in 1982. It entered Italy through three introduction events: directly from East Africa, from Albania and Greece, and from the area encompassing Moldavia and Ukraine. As in previously documented A1 epidemics of East European countries, HIV-1 A1 subtype spread in Italy in part through intravenous drug users. However, Eastern European women contributed to the penetration of such variant, probably through sex work.

Global Dispersal Pattern of HIV Type 1 Subtype CRF01_AE: A Genetic Trace of Human Mobility Related to Heterosexual Sexual Activities Centralized in Southeast Asia.

BACKGROUND: Human immunodeficiency virus type 1 (HIV-1) subtype CRF01_AE originated in Africa and then passed to Thailand, where it established a major epidemic. Despite the global presence of CRF01_AE, little is known about its subsequent dispersal pattern. METHODS: We assembled a global data set of 2736 CRF01_AE sequences by pooling sequences from public databases and patient-cohort studies. We estimated viral dispersal patterns, using statistical phylogeographic analysis run over bootstrap trees estimated by the maximum likelihood method. RESULTS: We show that Thailand has been the source of viral dispersal to most areas worldwide, including 17 of 20 sampled countries in Europe. Japan, Singapore, Vietnam, and other Asian countries have played a secondary role in the viral dissemination. In contrast, China and Taiwan have mainly imported strains from neighboring Asian countries, North America, and Africa without any significant viral exportation. DISCUSSION: The central role of Thailand in the global spread of CRF01_AE can be probably explained by the popularity of Thailand as a vacation destination characterized by sex tourism and by Thai emigration to the Western world. Our study highlights the unique case of CRF01_AE, the only globally distributed non-B clade whose global dispersal did not originate in Africa.

Increase in transmitted resistance to non-nucleoside reverse transcriptase inhibitors among newly diagnosed HIV-1 infections in Europe.

BACKGROUND: One out of ten newly diagnosed patients in Europe was infected with a virus carrying a drug resistant mutation. We analysed the patterns over time for transmitted drug resistance mutations (TDRM) using data from the European Spread program. METHODS: Clinical, epidemiological and virological data from 4317 patients newly diagnosed with HIV-1 infection between 2002 and 2007 were analysed. Patients were enrolled using a pre-defined sampling strategy. RESULTS: The overall prevalence of TDRM in this period was 8.9% (95% CI: 8.1-9.8). Interestingly, significant changes over time in TDRM caused by the different drug classes were found. Whereas nucleoside resistance mutations remained constant at 5%, a significant decline in protease inhibitors resistance mutations was observed, from 3.9% in 2002 to 1.6% in 2007 (p = 0.001). In contrast, resistance to non-nucleoside reverse transcriptase inhibitors (NNRTIs) doubled from 2.0% in 2002 to 4.1% in 2007 (p = 0.004) with 58% of viral strains carrying a K103N mutation. Phylogenetic analysis showed that these temporal changes could not be explained by large clusters of TDRM. CONCLUSION: During the years 2002 to 2007 transmitted resistance to NNRTI has doubled to 4% in Europe. The frequent use of NNRTI in first-line regimens and the clinical impact of NNRTI mutations warrants continued monitoring.

Trends and correlates of HIV-1 resistance among subjects failing an antiretroviral treatment over the 2003-2012 decade in Italy.

BACKGROUND: Despite a substantial reduction in virological failures following introduction of new potent antiretroviral therapies in the latest years, drug resistance remains a limitation for the control of HIV-1 infection. We evaluated trends and correlates of resistance in treatment failing patients in a comprehensive database over a time period of relevant changes in prescription attitudes and treatment guidelines. METHODS: We analyzed 6,796 HIV-1 pol sequences from 49 centres stored in the Italian ARCA database during the 2003-2012 period. Patients (n = 5,246) with viremia > 200 copies/mL received a genotypic test while on treatment. Mutations were identified from IAS-USA 2013 tables. Class resistance was evaluated according to antiretroviral regimens in use at failure. Time trends and correlates of resistance were analyzed by Cochran-Armitage test and logistic regression models. RESULTS: The use of NRTI backbone regimens slightly decreased from 99.7% in 2003-2004 to 97.4% in 2010-2012. NNRTI-based combinations dropped from 46.7% to 24.1%. PI-containing regimens rose from 56.6% to 81.7%, with an increase of boosted PI from 36.5% to 68.9% overtime. In the same reference periods, Resistance to NRTIs, NNRTIs and PIs declined from 79.1% to 40.8%, from 77.8% to 53.8% and from 59.8% to 18.9%, respectively (p < .0001 for all comparisons). Dual NRTI + NNRTI and NRTI + PI resistance decreased from 56.4% to 33.3% and from 36.1% to 10.5%, respectively. Reduced risk of resistance over time periods was confirmed by a multivariate analysis. CONCLUSIONS: Mutations associated with NRTIs, NNRTIs and PIs at treatment failure declined overtime regardless of specific class combinations and epidemiological characteristics of treated population. This is likely due to the improvement of HIV treatment, including both last generation drug combinations and prescription guidelines.

Trends and predictors of transmitted drug resistance (TDR) and clusters with TDR in a local Belgian HIV-1 epidemic.

We aimed to study epidemic trends and predictors for transmitted drug resistance (TDR) in our region, its clinical impact and its association with transmission clusters. We included 778 patients from the AIDS Reference Center in Leuven (Belgium) diagnosed from 1998 to 2012. Resistance testing was performed using population-based sequencing and TDR was estimated using the WHO-2009 surveillance list. Phylogenetic analysis was performed using maximum likelihood and Bayesian techniques. The cohort was predominantly Belgian (58.4%), men who have sex with men (MSM) (42.8%), and chronically infected (86.5%). The overall TDR prevalence was 9.6% (95% confidence interval (CI): 7.7-11.9), 6.5% (CI: 5.0-8.5) for nucleoside reverse transcriptase inhibitors (NRTI), 2.2% (CI: 1.4-3.5) for non-NRTI (NNRTI), and 2.2% (CI: 1.4-3.5) for protease inhibitors. A significant parabolic trend of NNRTI-TDR was found (p = 0.019). Factors significantly associated with TDR in univariate analysis were male gender, Belgian origin, MSM, recent infection, transmission clusters and subtype B, while multivariate and Bayesian network analysis singled out subtype B as the most predictive factor of TDR. Subtype B was related with transmission clusters with TDR that included 42.6% of the TDR patients. Thanks to resistance testing, 83% of the patients with TDR who started therapy had undetectable viral load whereas half of the patients would likely have received a suboptimal therapy without this test. In conclusion, TDR remained stable and a NNRTI up-and-down trend was observed. While the presence of clusters with TDR is worrying, we could not identify an independent, non-sequence based predictor for TDR or transmission clusters with TDR that could help with guidelines or public health measures.

Patterns of transmitted HIV drug resistance in Europe vary by risk group.

BACKGROUND: In Europe, a continuous programme (SPREAD) has been in place for ten years to study transmission of drug resistant HIV. We analysed time trends of transmitted drug resistance mutations (TDRM) in relation to the risk behaviour reported. METHODS: HIV-1 patients newly diagnosed in 27 countries from 2002 through 2007 were included. Inclusion was representative for risk group and geographical distribution in the participating countries in Europe. Trends over time were calculated by logistic regression. RESULTS: From the 4317 patients included, the majority was men-having-sex-with-men -MSM (2084, 48%), followed by heterosexuals (1501, 35%) and injection drug users (IDU) (355, 8%). MSM were more often from Western Europe origin, infected with subtype B virus, and recently infected (<1 year) (p<0.001). The prevalence of TDRM was highest in MSM (prevalence of 11.1%), followed by heterosexuals (6.6%) and IDU (5.1%, p<0.001). TDRM was predominantly ascribed to nucleoside reverse transcriptase inhibitors (NRTI) with a prevalence of 6.6% in MSM, 3.3% in heterosexuals and 2.0% in IDU (p = 0.001). A significant increase in resistance to non- nucleoside reverse transcriptase inhibitors (NNRTIs) and a decrease in resistance to protease inhibitors was observed in MSM (p = 0.008 and p = 0.006, respectively), but not in heterosexual patients (p = 0.68 and p = 0.14, respectively). CONCLUSIONS: MSM showed to have significantly higher TDRM prevalence compared to heterosexuals and IDU. The increasing NNRTI resistance in MSM is likely to negatively influence the therapy response of first-line therapy, as most include NNRTI drugs.

Identification of a new HIV-1 BC circulating recombinant form (CRF60_BC) in Italian young men having sex with men.

HIV-1 recombination, reverse transcriptase (RT) low fidelity and high replication rate are the drivers of variability and evolution on the global scale. Only few of these HIV-1 chimeric forms have been characterized in Europe, despite 20% of infections are due to unique or circulating recombinant forms worldwide. An outbreak of BC recombinants has been recently described in a southern region of Italy, Apulia, in men having sex with men (MSM) seeking sexual partners on-line. We analyzed the full length genome of HIV-1 BC recombinants harbored by three recently infected subjects, two MSM and a heterosexual woman, with no evidence of epidemiological link. The recombination analysis showed a unique recombination pattern of a subtype C genome with 3 subtype B fragments corresponding to HXB2 positions: [1-463] in the 5'LTR , [2804-3037] in RT and [8662-9548] corresponding to the C-terminal segment of gp41, nef and most of 3'LTR. Phylogenetic analysis revealed the South American origin of the C subtype parental strain. A research conducted in an Italian nationwide database provided six additional similar sequences from other Italian regions with identical recombination pattern in pol gene; a further BLAST search retrieved one full length genome isolated in France with the same mosaic pattern, except an additional B subtype short fragment in the integrase region. These recombinant isolates, designated CRF60_BC, led to the identification of the first Italian circulating recombinant form, which gave rise to an epidemic burst mainly involving MSM.

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.