HIV-1 GENETIC SUBTYPE A B RECOMBINANT STRAIN CAUSING AN EXPLOSIVE EPIDEMIC IN INJECTING DRUG-USERS IN KALININGRAD/

Objectives: To investigate the molecular epidemiology and genetic stru cture of the virus strain(s) causing an outbreak of HIV-1 infection in the Kaliningrad province of the Russian Federation and to investigate the relationship of this outbreak to some other emerging HIV-1 epidem ics in the countries of the former Soviet Union. Design: A molecular e pidemiological investigation was conducted in the city of Kaliningrad amongst individuals recently diagnosed as HIV-l-positive. Samples were also collected from neighbouring Lithuania and from the Ukraine. Meth ods: Incident and population data was collected from official health s tatistics in Kaliningrad. A standardized questionnaire was administere d to newly diagnosed individuals to assess risk factors for HIV-1 infe ction. For genotyping, two regions of the virus (env C2-V3 and gag NCp 7) were directly sequenced. Results: The number of newly diagnosed ind ividuals testing seropositive for HIV-1 infection in Kaliningrad rose from less than one per month to more than 100 per month during the per iod of July-October 1996. A total of 1335 new infections were identifi ed between 1 July 1996 and 30 June 1997. The main reported risk factor for HIV-1 infection (80%) was injecting drug use, in particular with a locally produced opiate. Sequence analysis of patient viruses in Kal iningrad (n = 50) showed that the epidemic was caused by a highly homo genous HIV-1 strain, recombinant between the genetic subtypes A and B. Comparison with subtype A strains prevalent amongst injecting drug us ers (IDU) in the Ukraine showed that one of these strains was the dire ct subtype A parent of the epidemic A/B recombinant strain in Kalining rad. Conclusions: The HIV-1 epidemic in Kaliningrad probably started f rom a single source, with rapid spread of the virus through the IDU po pulation. The origin of the epidemic strain is a recombination event o ccurring between the subtype A strain virus prevalent among IDU in som e southern CIS countries, and a subtype B strain of unknown origin. (C ) 1998 Lippincott Williams & Wilkins.