SEQUENCE NOTE Genetic Diversity of HIV Type 1 in Montenegro Massimo Ciccozzi, 1 Danijela Vujos ˇevic ´, 2 Alessandra Lo Presti, 1 Boban Mugos ˇa, 2 Zoran Vratnica, 2 Alessia Lai, 3 Dragan Laus ˇevic ´, 2 Nenad Dras ˇkovic ´, 4 Aleksandra Marjanovic, 2 Eleonora Cella, 1 Maria M. Santoro, 5 Claudia Alteri, 5 Lavinia Fabeni, 4 Marco Ciotti, 6 and Gianguglielmo Zehender 3 Abstract Human immunodeficiency virus type 1 (HIV-1) is characterized by high genetic variability due to its high replication rate and the lack of proofreading activity of the reverse transcriptase enzyme. On the basis of phylogenetic analysis performed on numerous isolates from all over the world, HIV-1 is subdivided into types, subtypes, subsubtypes, circulating recombinant forms, and unique recombinant forms. No data are currently available about the circulation of HIV-1 types in Montenegro. Here, we describe the genetic variability of HIV-1 strains identified in plasma samples of patients from Montenegro. Phylogenetic analysis on 32 HIV-1 sequences was carried out. The prevalent circulating HIV-1 subtype is B. The strains were interspersed within the tree. Two main clades (I and II) may suggest independent introductions of HIV-1 subtype B into Montenegro, although other epidemiological evidence will be needed to assume a small number of introductions. No obvious evidence of clustering by residence, age, or sex was found (data not shown). Nelfinavir resistance was found, though lopinavir is the only PI administered. Continuous monitoring of HIV-1-infected individuals is crucial to a better understand of the epidemiology of the B subtype in Montenegro. Introduction H uman immunodeficiency virus type 1 (HIV-1) infec- tion continues to spread rapidly throughout the world. According to the UNAIDS/WHO (December 2009) report, an estimated 33.4 million people are living with the virus worldwide. Recombination coupled with the lack of proof- reading activity of the reverse transcriptase (RT) and the rapid turnover of HIV-1 in infected individuals are at the origin of the high genetic variability and diversification of the virus. 1–3 The majority of HIV-1 strains cluster within a large group called M (for Main), which includes nine subtypes (A–D, F–H, J, and K), phylogenetically distinct. Subsubtypes A and F can be further subdivided into subsubtypes A1–A4 and F1 and F2, respectively. A number of intersubtype recombinant viruses are also observed. When such recombinant viruses spread within the human population they become circulating re- combinant forms (CRFs); when they remain restricted to a limited number of individuals they are called unique re- combinant forms (URFs). 4–6 The other groups are N, O, and P. Epidemiological data indicate that the impact of the HIV-1 epidemic on Balkan countries, which are part of central Eur- ope, is still limited. By contrast, in southern Mediterranean countries, although the number of newly diagnosed cases reported among injection drug users is declining, the HIV prevalence remains high. 7,8 Montenegro is a young state that gained independency in May 2006. In this country the most recent official census data (2003) sets the population at 620,145 individuals. Although some basic information on the main characteristics of indi- viduals affected by HIV/AIDS in the Balkans is available, little is known about the circulation of HIV-1 subtypes in Montenegro. The first cases of HIV-1 infection and AIDS were described in an intravenous drug user and sailor, respectively. Two cases of mother-to-child transmission were documented in 1989. 9 Since then, new diagnoses of HIV infection and AIDS are subjected to mandatory reporting to the National Institute of Public Health (NIPH) of Montenegro. In spite of significant progress made in accessing diagnostics and treatment, no information is currently available on the circulation of HIV-1 subtypes and the prevalence of antiretroviral drug resistance in Montenegro. 1 Department of infectious Diseases, Instituto Superiore di Sanita ` , Rome, Italy. 2 Institute of Public Health, Podgorica, Montenegro. 3 Department of Clinical Sciences, University of Milan, Milan, Italy. 4 Clinical Centre, Podgorica, Montenegro. 5 Department of Experimental Medicine and Biochemical Sciences, University of Tor Vergata, Rome, Italy. 6 Laboratory of Molecular Virology, Foundation Polyclinic Tor Vergata, Rome, Italy. AIDS RESEARCH AND HUMAN RETROVIRUSES Volume 27, Number 00, 2011 ª Mary Ann Liebert, Inc. DOI: 10.1089/aid.2010.0323 1