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

Abstract

Transmission of HIV-1 and drug resistance continue to occur at a considerable level in Italy, influenced mainly by changes in modality of infection. However, the long period of infectivity makes difficult the interpretation of epidemiological networks, based on epidemiological data only. We studied 510 naive HIV-1-infected individuals, of whom 400 (78.4%) were newly diagnosed patients with an unknown duration of infection (NDs), with the aim of identifying sexual epidemiological networks and transmitted drug resistance (TDR) over a 7-year period. Clusters were identified by Bayesian methods for 412 patients with B subtype; 145 individuals (35.2%) clustered in 34 distinct clades. Within epidemiological networks males were 93.1% (n = 135); the same proportion of patients has been infected by the sexual route; 62.1% (n = 90) were men having sex with men (MSM) of whom 67.8% (n = 61) were NDs. Among heterosexuals (n = 44), males were predominant (79.5%, n = 35) and 77.3% (n = 34) were NDs. TDR in clusters was 11.7 % (n = 17), of whom 76.5% (n = 13) was found in MSM. TDR was predominantly associated with NRTI resistance in individuals with chronic infection (n = 11). A high prevalence of epidemiological networks has been found in the metropolitan area of Milan, indicating a high frequency of transmission events. The cluster analysis of networks suggested that the source of new infections was mainly represented by males and MSM who have long lasting HIV-1 infection. Notably, the prevalence of resistanceconferring mutations was higher in chronically infected patients, carrying mainly resistance to thymidine analogs, the backbone of first antiretroviral (ARV) generation. Intervention strategies of public health are needed to limit HIV-1 transmission and the associated TDR.

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

“…By a phylodynamic approach, we observed that the time of penetration of HIV-1 B variant carried by TSWs took place as early as that established for B subtype in Italy 26…”

Trends in Prevalence of HIV‐1 Drug Resistance in Thailand 2009–2010

“…The capacity of HIV to develop drug resistance mutations is a major obstacle to effective long-term therapy (22)(23)(24)(25)(26)(27). The increased use of combination antiretroviral therapies for HIV-1 infection has led to the emergence of viral strains resistant to all licensed reverse transcriptase inhibitors (RTIs) and protease inhibitors (PIs) (27)(28)(29)(30)(31). Mutations selected by drug resistance are classified as primary and secondary mutations.…”

“…Furthermore, incomplete suppression of viral replication promotes the development of broader drug resistance, compromising subsequent treatment regimens. A number of studies have evaluated rates of resistance mutations in recently transmitted virus by looking at subjects with primary infection (28,29,32,33). Reported rates of drug resistance in these studies vary from 1.4 to 37.0% with most of the resistance mutations seen in the RT gene (23,27,31,(34)(35)(36)(37)(38)(39)(40).…”

“…High prevalence of drug‐resistant virus among HIV‐1 infected patients on therapy has increased the probability of transmission of virus resistant to one or more classes of antiretroviral drugs . Complete suppression of HIV‐1 could be compromised if therapy‐naïve patients already harbor virus with mutations conferring resistance to antiretroviral drugs used for initial therapy . Furthermore, incomplete suppression of viral replication promotes the development of broader drug resistance, compromising subsequent treatment regimens.…”

HIV-1 Subtype F1 Epidemiological Networks among Italian Heterosexual Males Are Associated with Introduction Events from South America

“…Information on epidemiological networks has been obtained in small areas or in B-subtype restricted population [16], [17].…”