CROI 2015 Program and Abstracts

Abstract Listing

Poster Abstracts

1020 Seminal Shedding of CMV and HIV Transmission Among MenWho Have Sex With Men Sara GianellaWeibel 1 ; Konrad Scheffler 1 ; Sanjay Mehta 1 ; Susan J. Little 1 ; Lorri Freitas 2 ; Sheldon R. Morris 1 ; David M. Smith 1 1 University of California San Diego, La Jolla, CA, US; 2 County of San Diego Public Health Services, San Diego, CA, US

Background: Almost all HIV-infected men who have sex with men (MSM) in San Diego are seropositive for cytomegalovirus (CMV) and approximately half shed seminal CMV at any given time. This shedding is associated with detectable HIV in semen, enhanced HIV replication, up-regulation of CCR5, and ultimately with HIV transmission. Here, we estimate the population attributable risk (PAR) of CMV shedding to the number of HIV transmissions among MSM living in San Diego. We compare this estimate to the PAR for other sexually transmitted infections (STIs)- gonorrhea, syphilis, Chlamydia and herpes simplex virus type 2 (HSV-2). Methods: We estimate relative risks for CMV shedding, bacterial STI and HSV-2 based on the number of transmissions observed in two studies of 47 epidemiologically and phylogenetically linked MSM pairs where the potential source partner was HIV-infected while the potential recipient partner was initially HIV-uninfected. PAR estimates were calculated by combining these estimates with the risk factor prevalences of seminal CMV shedding, bacterial STI, HSV-2 serostatus, and incidence of HIV among MSM in San Diego. Results: In 2013, 339 HIV diagnoses among MSM were reported in San Diego. Using data collected fromMSM in San Diego, we estimate that: 51% shed CMV in their semen at any time, prevalence of bacterial STI is 15% and seropositivity for HSV-2 is 41%. Transmission of HIV from the potential source partner to recipient partner occurred in: (i) 53% versus 25% (source partner shedding CMV versus not shedding CMV), (ii) 100% versus 37% (source partner with bacterial STI versus no STI), (iii) 42% versus 28% (source partner HSV-2 seropositive versus seronegative). None of the potential source partners had detectable HSV-2 in semen. Based on these data, we calculate that over a third of HIV transmissions among MSM in San Diego (37%) could be attributable to CMV shedding (111 transmission events), compared to no more than 21% for bacterial STI (62 events) and 17% for HSV-2 (51 events). Conclusions: This study supports the hypothesis that CMV shedding among MSM contributes to a large proportion of HIV transmissions in San Diego. Such contribution seems to be larger than that of bacterial STI and HSV-2. Confirming this hypothesis would require a large randomized placebo-controlled clinical trial, which will be difficult with currently approved anti-CMV therapies given their inherent toxicities, but newer anti-CMV therapies and vaccines may hold promise. 1021 Risk Factors for Acute and Early HIV Infection Among MSM in San Diego, 2008–2014 Martin Hoenigl ; Christy M. Anderson; Sanjay Mehta; Nella L. Green; Davey M. Smith; Susan Little University of California San Diego, San Diego, CA, US Background: Men who have sex with men (MSM) presenting for HIV screening may represent a sub-segment of the MSM population at higher risk for acquisition of HIV infection. Methods: We analyzed risk behavior reported for the 12 months prior to testing in MSM receiving the “Early Test”, a community-based, confidential acute and early HIV infection (AEH) screening program in San Diego, CA, between April 2008 and July 2014. Analyses were performed using Chi-Square and Mann Whitney U test as well as Cox regression. 14 explanatory variables were included in the final multivariable model and selected with a forward stepwise procedure. Results: A large cohort was analyzed (n=14,612) and 8935 (61%) of those were MSM, and 200 MSM (2.3%; 219 newly diagnosed chronically infected MSM were excluded) were diagnosed with AEH. Individuals with AEH were significantly younger (median 30 [IQR 25-40] vs. 33 [IQR 27-43], p=0.001) and reported significantly more male sex partners (median 10 [IQR 5-20] vs. 5 [IQR 3-10], p<0.001) than those with negative test results. No differences were found with regard to race or ethnicity. Prevalence rates by risk behavior are depicted in the table. Interestingly, unprotected receptive anal intercourse (URAI) was associated with only a slight elevation of AEH prevalence (3.11% vs. 2.3%), which is similar to only reporting 5 or more male partners (3.06% vs. 2.3%). However, we found a dose response with number of male partners when combining URAI (URAI and 3 male partners was 3.4%, URAI and 5 male partners 3.71% and URAI with 10 partners was 4.29%). Therefore, the combination of URAI and 5 or more (i.e. above the median) male partners was chosen for our model, and UARI with a HIV positive male was the strongest predictor of seroconversion, followed by number of male partners, the combination of URAI and 5 or more male partners, syphilis diagnosis within last 12 months and methamphetamine use.

Poster Abstracts

600

CROI 2015