Presence of HIV-1 CRF35_AD in Iran.

Editor: Human immunodeficiency virus type 1 (HIV-1) is known for its remarkable genomic variability due to (1) the error-prone nature of the reverse transcriptase (RT), which has no proofreading ability and can generate nucleotide substitutions, deletions, and=or substitutions as well as to (2) recombination between different HIV-1 strains. HIV-1 has been classified into three groups: M (major), O (outlier), and N (new, non-M–non O). The M group, which is associated with the pandemic, is subdivided into distinct clades or subtypes (A–D, F–H, J, and K), circulating recombinant forms (37 CRFs have been described so far), and unique recombinant forms (URFs). This extraordinary variability of HIV-1 is associated with various geographic distributions of subtypes and CRFs. Generally, subtype A is the principal HIV-1 subtype found in Central African countries. Subtype B is predominant in the United States, Europe, Australia, and Brazil. Subtype C is prevalent in South Africa, Ethiopia, and India. CRF01_AE is common in Southeast Asia. In spite of limited information on the molecular characterization of HIV-1 in Asian countries, the distribution of HIV subtypes=CRFs appears to be remarkably diverse. In Uzbekistan, intravenous drug users (IDUs) have been found to be infected with HIV-1 subtype A as well as CRF03_AB; an outbreak of CRF02_AG cases has also been reported in this country. In Kazakhstan, IDUs were reported to have HIV-1 subtype A. In the Islamic countries, Turkey has reported subtypes A, B, C, D, and G as well as F and Lebanon has reported both HIV-1 (subtypes A, B, C, D, and G) and HIV-2. In Yemen, HIV-1 subtypes A, B, C, and D as well as some URFs have been reported.7 In Pakistan, data show HIV-1 clade A to be prevalent among the IDUs in Karachi. The first case of HIV=AIDS in Iran was reported in 1987; subtypes A and B have been characterized among, respectively, IDUs and hemophiliacs. Recently, the same subtype A has been reported in the Mashhad province of Iran. In this letter we show that the pattern of HIV-1 subtypes=CRFs in Iran is more complicated than previously reported. We have analyzed the reverse transcriptase (RT), protease (Prot), and envelope (Env) sequences of HIV-1 isolates from 18 treatment-naive patients recruited in the Hepatitis and HIV Clinics, Iranian Blood Transfusion Organization, Tehran. The plasma RNA was isolated using a Tripure RNA Isolation kit (Roche, West Germany) according to the manufacturer’s protocol. Isolated RNA was resuspended in 20 ml of nuclease-free water. The RT, Prot, and Env regions were amplified by nested polymerase chain reaction using sets of primers described on the French ANRS website. The fragments that were obtained were sequenced on both strands using an AB-Prism Big Dye Terminator Cycle Sequencing Kit on an automated sequencer. The ABI file was converted to an scf file by chromas software. Scf files were further analyzed by CEQ-8000 software (Beckman-Coulter) with an HBX-2 reference gene for putative polymorphism. The nucleotide sequences derived for RT, Prot, and Env were aligned by the Clustal W 1.74 software multiple sequence alignment program with known reference strains of groups M and N from the HIV-1 gene databank. Phylogenetic trees were inferred using the neighbor-joining method from a matrix of distances calculated after gap stipping of alignments with a Kimura two-parameter algorithm. We obtained full or partial sequence results for 13 isolates (Table 1). GenBank accession numbers FJ392730 to FJ392755. They show that all sequences cluster with CRF35_AD, which has been observed recently in IDUs of Kabul, Afghanistan. We suggest that CRF35_AD has been transported from Afghanistan to Iran through drug trafficking, but more extensive comparative studies of the different isolates are needed. Moreover, although most of our Iranian patients are IDUs, a minority exhibits other risk factors (heterosexual transfer and one MSM). The conclusion is that the pattern of subtypes and CRF(s) in Iran is more complicated than previously reported, with three different HIV-1 strains now circulating in the country: A, B, and CRF35_AD.