CROI 2017 Abstract e-Book

Abstract eBook

Poster and Themed Discussion Abstracts

188 TEMPORAL CHANGES IN HIV TRANSMISSION PATTERNS AMONG YOUNG MEN WHO HAVE SEX WITH MEN Nivedha Panneer 1 , Y. O. Whiteside 2 , Anne Marie France 2 , Joel O. Wertheim 3 , Alexandra Oster 2 1 Oak Ridge Inst for Sci and Educ, Atlanta, GA, USA, 2 CDC, Atlanta, GA, USA, 3 Univ of California San Diego, San Diego, CA, USA

Background: In the United States, young men who have sex with men (YMSM), particularly black/African American (black) or Hispanic/Latino YMSM, bear a disproportionate burden of HIV infections. HIV transmission among YMSM has been found to be highly assortative by race but disassortative by age. We examined temporal trends in transmission for subgroups of YMSM (MSM aged 13-24 years). Methods: We analyzed HIV-1 pol sequences reported to the National HIV Surveillance System for all MSM aged ≥13 years who had HIV diagnosed during 2006–2013 and were from 26 jurisdictions. We identified potential transmission pairs at a genetic distance threshold of ≤1.5% and constructed transmission networks using HIV-TRACE. For YMSM, we determined race/ethnicity and age of potential transmission partners. Assuming HIV was acquired from only one person, we assigned partners of YMSMwith >1 transmission partner a weight equal to the inverse of the number of partners. We constructed two multivariable logistic regression models and calculated prevalence ratios (PRs) and 95% confidence intervals (CIs) to examine the change from 2006–2009 to 2010–2013 in the proportion of potential transmission partners 1) of the same race/ethnicity and 2) at least 5 years older, for each subgroup of YMSM, adjusting for geography and transmission category. Results: Of 7,867 YMSM with a potential transmission partner, 67% had partners of the same race/ethnicity and 36% had partners >5 years older. Transmission among blacks remained highly assortative by race, with approximately 80% of blacks linking to other blacks. Assortativity by race/ethnicity among Hispanics/Latinos increased over time, with substantial increases seen in MSM aged 13-19 years (from 46% to 59%, PR=1.34, CI=1.10–1.64). Although a higher proportion of white YMSM had older transmission partners (48%) compared with blacks (30%) and Hispanics/Latinos (42%), the proportion of older transmission partners increased over time for all racial/ethnic groups, with the most substantial increases among blacks and Hispanics/Latinos aged 13-19 years (black: PR=1.42, CI=1.23–1.65; Hispanic/Latino: PR=1.31, CI=1.05–1.64). Conclusion: These data provide evidence for continued transmission among networks of black YMSM and expansion of transmission among networks of Hispanic/Latino YMSM. Additionally, YMSM are increasingly linked to older partners. Prevention programs aimed at reducing incidence among YMSMmay be strengthened by also ensuring that older MSM are virally suppressed.

Poster and Themed Discussion Abstracts

189 PHYLODYNAMIC ANALYSIS AIDS PARTNER SERVICES BY IDENTIFYING UNREPORTED TRANSMISSION

Ellsworth Campbell 1 , Anupama Shankar 1 , Emily Westheimer 2 , Cynthia L. Gay 3 , Stephanie E. Cohen 4 , Jin-Fen Li 1 , Jeffrey A. Johnson 1 , Philip J. Peters 1 , WilliamM. Switzer 1 1 CDC, Atlanta, GA, USA, 2 New York City DHMH, New York, NY, USA, 3 Univ of North Carolina at Chapel Hill, Chapel Hill, NC, USA, 4 San Francisco Dept of Pub Hlth, San Francisco, CA, USA Background: HIV transmission links can be difficult to detect via routine partner services investigations. We used phylodynamic techniques to infer transmission links between participants of a prospective study of acute HIV infection (AHI) conducted in North Carolina, New York City, and San Francisco from 2011-2013. Methods: Participants newly diagnosed with either acute or established HIV infection were offered partner notification services and contact information was elicited for sex partners (epi links). Where HIV-1 polymerase (pol) sequences were available, transmission linkages were inferred when the genetic distance between pol sequences was <1.5%. Genetic distances (d) were calculated using a nucleotide substitution model after pairwise alignment to the HXB2 reference sequence. Drug resistance (DR) was inferred from pol sequences using SIERRA. Results: Among the 813 newly diagnosed participants (103 with acute and 710 with established HIV infection) with a pol sequence available, 457 sex partners were reported of whom 35 (7.7%) were other participants with an available pol sequence (epi links). Among these 35 HIV epi links, 23 (65.7%) were genetically supported and 12 (34.3%) were not genetically supported. Only five epi links were between participants with acute infection and none were genetically supported. In contrast, phylodynamic inference identified 102 unreported putative transmission links including 12 links between persons with acute infection (p<0.001).The mean genetic distance between pol sequences from persons with acute HIV infection (d=0.7%) was significantly lower (p<0.001) than that of inferred links between persons with established HIV infections (d=0.9%), suggesting more recent transmission among the AHI group. Importantly, all putative transmission links between persons with acute infection were found among large clusters with > five members and all exhibited evidence of transmitted DR. Mean transmission cluster size was larger among those who reported having met sexual partners online (4.8, 95% CI [4.0-5.6]) than those that did not (3.4, 95% CI [2.8-3.4], p<0.05). Conclusion: Phylodynamic inference of HIV transmission identified four times as many transmission links as partner services alone. Routinely applied, this technique can illuminate transmission patterns of public health importance not readily captured by conventional partner services investigations. 190 NEUTRALIZING ANTIBODIES IN HUMANS INFECTED WITH ZOONOTIC SIMIAN FOAMY VIRUSES Caroline Lambert, Julie Gouzil, Léa Richard, Réjane Rua, Edouard Betsem, Antoine Gessain, Florence Buseyne Inst Pasteur, Paris, France Background: Simian foamy viruses (SFVs) are efficiently transmitted from non-human primates to humans, establishing persistent infection in the new host. Neither pathogenic effects nor human-to-human transmission have been reported, suggesting that immune control of this retrovirus is efficient. Here, we aimed at studying the humoral response. We used viral strains isolated from infected humans to study the neutralizing antibodies present in the plasma of SFV-infected people living in rural areas of South Cameroon and Gabon.

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CROI 2017