HIV‑1 molecular epidemiology in the Balkans: a melting pot for high genetic diversity

The Balkans is a gateway between Europe, Asia, and the African continent, a fact with potential important consequences on the epidemiology of HIV‑1 infection in the region. The duration of the HIV‑1 epidemics in many countries of the Balkans is similar to the one in the Western European countries. However, striking differences exist in several countries of the region in both the epidemic situation and, even more so, in our knowledge about it. In particular, the molecular epidemiology of HIV in the Balkans is largely unknown. In order to gain some preliminary insight into HIV‑1 diversity in the region, we reviewed the available molecular epidemiology data about HIV‑1 diversity in 10 countries of the region: Albania, Bulgaria, Croatia, Greece, Montenegro, Romania, Slovenia, Serbia, Turkey, and Hungary, a neighboring country to four Balkan countries. The data were obtained either from published studies or in direct communication with the participating members. The existing molecular epidemiology data revealed a broad diversity in subtype distribution among Balkan countries. In several countries, subtype B is predominant (e.g. Serbia, Slovenia, and Hungary), while in others the proportion of non‑B subtypes is much larger (Albania subtype A, Romania subtype F). In some areas, HIV‑1 subtype distribution is marked by divergence between different risk groups or transmission routes (e.g. Croatia). Recently, HIV‑1/AIDS epidemics in Eastern Europe have been among the fastest growing in the world. Many major contributing factors for the breakout and spread of these epidemics are present in many of the Balkan countries, as reflected through the process of social transition, wars, unemployment, extensive drug use, high sexual risk behavior, as well as other factors. Yet, in the Balkan countries the prevalence rate of HIV‑1 infection is low, under 0.1 percent. Concomitantly, the molecular epidemiology of HIV‑1 in the Balkans has not been thoroughly studied so far. The review and analysis of the available data indicate a broad diversity of circulating HIV‑1 subtypes in the region, with the predominance of non‑B clades in some countries, underscoring the need for an ongoing surveillance of HIV‑1 diversity. The setup of a collaborative network might provide important information for the better management and control of the HIV‑1 epidemic in the area.