Research Findings - Multi-Division Research

Injection Drug Use Associated with Increased Multiplicity of HIV Infection in Women

Genetic recombination of multiple viruses at the cellular level within a single host is believed to contribute to HIV-1 diversity and escape from host immunity and antiviral therapies. Multiple infection rates calculated from observed inter- or intra-subtype recombinants in individual patients are estimates of the cumulative multiple infection rates over the evolutionary history of the viral strains involved; however these estimates can be influenced by factors other than recombination. If selection over time either favors or acts against multiple infection recombinants, the estimated multiple infection rates will be biased. Therefore, one must characterize a population of infected individuals directly to truly assess the rate and dynamics of multiple infection. In this prospective longitudinal study of 58 HIV-1 positive participants from The Women's Interagency HIV Study (WIHS), Dr. Markham and colleagues estimated the incidence of multiple infection and the impact of the risk factor of injection drug use (IDU) on multiple infection by including both IDUs and non-IDUs in the sample. By using an analytical technique developed specifically to detect intra-strain recombination in singly infected hosts that can yield a statistically significant inference of recombination with as few as six nucleotide differences between the parental genomes, the role of recombination at all these biological levels could be examined with much greater resolution than previous studies. The study found that 40% of the samples had multiple HIV-1 infections. Injection drug use significantly increased the incidence of multiple infections and significantly increased the rate of observed recombinants. Multiple infection and recombination significantly add to the genetic diversity of HIV-1 and its evolutionary potential, and injection drug use significantly increased both. Templeton AR, Kramer MG, Jarvis J, Kowalski J, Gange S, Schneider MF, et al., Multiple-infection and recombination in HIV-1 within a longitudinal cohort of women. Retrovirology. 2009 Jun 3;6:54.