Short communication: molecular epidemiology of HIV type 1 infection in northern Greece (2009-2010): evidence of a transmission cluster of HIV type 1 subtype A1 drug-resistant strains among men who have sex with men

Abstract

A prospective molecular epidemiology study of HIV-1 infection was conducted in newly diagnosed and antiretroviral-naive patients in Northern Greece between 2009 and 2010 using a predefined enrolling strategy. Phylogenetic trees of the pol sequences obtained in this study with reference sequences indicated that subtypes B and A1 were the most common subtypes present and accounted for 44.9% and 42.9%, respectively, followed by subtype C (3.1%), CRF02_AG (4.1%), CRF04_cpx (2.0%), and subtypes CRF01_01, F1, and G (1.0%). A high rate of clustered transmission of subtype A1-resistant strains to reverse transcriptase (RT) inhibitors was observed among men having sex with men. Indeed, 15 out of 17 study subjects (88.2%) infected with transmitted drug resistance (TDR) strains were implicated in transmission clusters, 10 of whom (66.7%) were men who have sex with men (MSM), and were also infected with subsubtype A1 strains. The main cluster within subtype A1 (I) included eight men reporting having sex with men from Thessaloniki infected with dual-class RT-resistant strains carrying both T215C and Y181C mutations.

FIG. 1.

(A) Neighbor-joining tree of pol (protease and partial reverse transcriptase) sequences, constructed as described in the text. The circular brackets on the periphery of the tree indicate the determined subtypes and circulating recombinant forms (CRF) as described in the text. The tips of reference sequences are shown with black lines and the patient sequences with circles; those with drug resistance mutations are indicated with open circles. Only consensus bootstrap values greater than 70% out of 1,000 replications are shown at several nodes. The scale at the middle of each tree is used to obtain the percent divergence between any two sequences. Clusters of sequences with transmitted drug resistance mutations (TDRM; indicated with open circles) that have a significant statistical support (>85% bootstrap support) for the branch subtending the cluster and a mean genetic distance of <0.015 nucleotide substitutions per site are indicated by dotted ovals. (B) The four observed clusters of drug-resistant strains are magnified for better viewing and the drug resistance mutations associated with each sequences are depicted at the edge of the branches.