High-risk sexual practices contribute to HIV-1 double infection among MSM in Madrid".

BACKGROUND Data on the prevalence of double infection (DI) in HIV individuals are lacking in Spain. To fill this gap, we analyzed the prevalence of DI in a cohort of men who have sex with men (MSM) and examined factors contributing to DI. METHODS We selected 81 MSM attending Centro Sanitario Sandoval, a Sexually Transmitted Diseases Clinic in Madrid. We obtained by ultra-deep sequencing the proviral sequences in gag and env genes and performed a phylogenetic analysis for the identification of DI. Clinical, behavioral, host and viral factors were studied for its association with DI. RESULTS We detected 6 individuals with DI and one case of superinfection with a global prevalence of 8.6%. The genetic distance among the subtype B viruses in mono-infected individuals (24.4%) was lower than the distance between the two viruses in subtype B DI individuals (29.5%). Individuals with a high number of sexual contacts (>25 partners/year) had an 8.66 times higher risk of DI (p=0.017). CONCLUSIONS In this MSM cohort the prevalence of HIV DI was estimated at 8.6%. DI was strongly associated with the number of sexual partners. Because of the pathogenic consequences of HIV DI, this high prevalence should promote Public Health Programs targeted to high risk population such as MSM for the control of HIV infection and DI. HIV DI should be considered for a better clinical management of these individuals.