CROI 2018 Abstract eBook

Abstract eBook

Poster Abstracts

associated with low-level RPV were detected in 25% of mice infected during RPV LA PrEP usually at frequencies of <5% of HIV-1 RNA genomes. E138K and mutations that do not confer RPV resistance (M184I and V179I) were also observed in some mice. E138K and M184I previously were shown to develop via APOBEC3-mediated hypermutation. Conclusion: Biological concentrations of RPV in the genital tract and plasma were not sufficient to prevent vaginal transmission of a highly infectious HIV-1 molecular clone. While 8-fold higher RPV concentrations inhibited low RPV-resistant Y181C HIV-1, they were not sufficient to inhibit Y181V HIV-1, which has 30-fold resistance to RPV. Our data suggest that both level of resistance and infectivity affect the ability of HIV-1 to be transmitted during PrEP. HIV-1 did not develop high level or high frequency RPV resistance most mice infected during RPV LA PrEP. The impact of low frequency RPV-resistant viruses on virologic outcome during antiretroviral treatment remains to be determined. 563 FIELD EVALUATION OF A DUAL HIV/SYPHILIS TEST IN A COMMUNITY- BASED CLINIC, LOS ANGELES Chrysovalantis Stafylis 1 , Lauren J. Natoli 2 , Katheryn Salow 2 , Emma Davidson 2 , Yancy Granados 2 , Mark R. McGrath 2 , Jeffrey D. Klausner 1 1 University of California Los Angeles, Los Angeles, CA, USA, 2 AIDS Healthcare Foundation, Los Angeles, CA, USA Background: High rates of syphilis and HIV infection among high-risk populations in the United States call for strategies to identify and treat new cases early. Dual rapid assays offer a convenient way to screen simultaneously for both infections, but to date there is no FDA-approved device. The INSTI Multiplex HIV-1/HIV-2/Syphilis Antibody Test (BioLytical, Richmond, BC, Canada) is a single use, rapid flow-through in vitro qualitative immunoassay detecting IgG antibodies to HIV-1(gp41), HIV-2(gp36) and Treponema pallidum(p17, p47) in whole/fingerstick blood, serum or plasma. Laboratory evaluations on serum have proven the device highly sensitive and specific for both infections. The field performance of the Multiplex was evaluated in a community clinical setting. Methods: The study was conducted between August 2016 and September 2017 among adult patients visiting two outpatient clinics of the AIDS Healthcare Foundation in Los Angeles, California; the Healthcare Center serves patients with HIV infection, while the Wellness clinic offers HIV/STD testing. Fingerstick whole blood was tested on the Multiplex and it was compared to serum tested in the laboratory for HIV and TP antibodies. Participant’s infection status for HIV was determined using a 4th generation assay (Abbott Architect HIV Ag/ Ab Combo, Abbott, IL). For syphilis, TP particle agglutination (Serodia TPPA, Fujirebio Inc, PA) with reflex to RPR and titer was performed. Sensitivity and specificity were calculated; sensitivity for syphilis is presented by RPR titer (Non- Reactive, 1:1-1:2, 1:4, ≥1:8). The exact binomial method was used to determine 95% confidence intervals (CI). Results: In total, 156 patients participated in the evaluation; 55 patients had detectable HIV antibodies, 51 had antibodies for TP and 39 had a reactive RPR. There were no invalid tests. Sensitivity for HIV antibodies was 98.2%(90.3%,99.9%) and specificity was 100%(96.4%,100%). Among TPPA confirmed specimens, sensitivity was 8.3%(0.2%,38.5%) in those with a Non- Reactive RPR, 40%(21.1%,61.3%) for RPR titers 1:1 and 1:2, 60%(14.7%,94.7%) for RPR titer 1:4 and 100%(66.4%,100%) for RPR titer ≥1:8. Specificity was 97.1% (91.8% - 99.4%). Conclusion: The INSTI Multiplex showed excellent performance for detection of HIV antibodies. The test is more sensitive in specimens with higher RPR antibody titers, when recent or active infection is more likely. Further research is required to evaluate its role in screening programs. 564 FIELD EVALUATION OF A DUAL ANTIBODY RAPID TEST FOR HIV/SYPHILIS INFECTION, VIETNAM Keenan Withers 1 , Minh D. Nguyen 2 , Chrysovalantis Stafylis 1 , Loc Pham 2 , Le Minh Giang 2 , Jeffrey D. Klausner 1 1 University of California Los Angeles, Los Angeles, CA, USA, 2 Hanoi Medical University, Hanoi, Vietnam Background: Access to reliable, rapid and easy to use point-of-care (POC) tests for HIV and syphilis in Vietnam are limited. The SD BIOLINE HIV/Syphilis Duo rapid test (Standard Diagnostics, Inc, Gyeonggi-do, Republic of Korea) is a qualitative point-of-care, rapid immunoassay that detects antibodies (IgG, IgM, IgA) to HIV-specific antigens (HIV-1 gp41, sub O, HIV-2 gp36) and recombinant Treponema pallidum (TP) antigen (17 kDa) via fingerprick/whole blood, serum and plasma. This test has shown excellent performance in a

number of field settings including Myanmar, Haiti, Kenya, and Ghana. However, data on its performance in Vietnam is currently unknown. We evaluated the field performance of the SD BIOLINE among two special populations in Hanoi, Vietnam -men who have sex with men (MSM) and pregnant women. Methods: The study was conducted at a sexual health clinic for MSM and an antenatal care center. Participants who were 18 years and older and willing to return for counseling, testing and treatment were invited to participate in the study. We intentionally recruited a large proportion of MSM with known HIV and/or prior syphilis infection. Participant sera were obtained for reference testing of HIV and TP antibodies using SD BIOLINE HIV ½ 3.0 (Standard Diagnostics Inc., Republic of Korea) and Treponema pallidum particle agglutination (SERODIA-TPPA, Fujirebio Diagnostics, Japan) respectively. Sensitivity and specificity were calculated. The exact binomial method was used to calculate 95% confidence intervals (CI). Concordance between the SD BIOLINE Duo HIV/syphilis and reference tests were measured by Cohen’s kappa statistic. Results: Of 280 participants, 100 (35.7%) were MSM and 180 (64.3%) were pregnant women. The median age was 26 years, range 18 – 49. Of MSM, 17 (17.0%) were HIV-infected and 49 (49.0%) were TPPA-positive. All women were negative for both HIV and TP antibodies. Sensitivity and specificity were 100.0% (95% CI: 80.5% - 100.0%) and 100.0% (95% CI: 98.6% - 100.0%), respectively, for HIV antibodies with a kappa coefficient of 1.00 (95% CI, 1.00 - 1.00). For TP antibodies, the sensitivity and specificity were 83.1% (95% CI: 71.0% - 91.6%) and 100.0% (95% CI: 98.3% - 100.0%), respectively with a kappa coefficient of 0.89 (95% CI: 0.82 - 0.96). Conclusion: The test performed well in this field setting. This rapid POC diagnostic dual test has the potential to help increase screening for both syphilis and HIV infections in resource-limited settings such as Vietnam. 565 TIME FROM HIV INFECTION TO EARLIEST DETECTION FOR 4 FDA- APPROVED POINT-OF-CARE TESTS Kevin P. Delaney 1 , Lauren Violette 2 , George A. Ure 2 , Andy M. Cornelius- Hudson 2 , Lisa Niemann 2 , Laura Wesolowski 1 , Pollyanna Chavez 1 , Steven Ethridge 1 , Vanessa McMahan 2 , Hollie Clark 1 , David A. Katz 2 , Joanne Stekler 2 1 CDC, Atlanta, GA, USA, 2 University of Washington, Seattle, WA, USA Background: Estimates are available for time from HIV infection to first detection with FDA-approved rapid tests using plasma seroconversion panels. However, most point-of-care (POC) HIV tests that are critical for HIV screening programs and entry to HIV and PrEP care are performed on unprocessed whole blood, fingerstick blood, or oral fluid. We assessed seroconversion sensitivity for tests when using these unprocessed specimen types. Methods: Participants were at high risk for HIV infection and seeking HIV testing or were referred to the study after diagnosis with early infection. Participants were tested with a panel of POC tests on up to 3 specimen types (Table). Those with discordant results were tested repeatedly with the test panel through seroconversion. Through 8/25/2017, there were 1,211 participants, including 43 newly identified as HIV infected; this analysis is limited to the 12 HIV-infected participants with discordant results and/or documented dates of last negative HIV test. All 12 initiated treatment a median of 2 days after enrollment (range: -10 to 37 days). We estimated the infection date based on changes in viral load, reported symptoms of acute HIV infection, and HIV risk history, and describe the distribution of time from infection to first detection with each test and specimen type combination. Results: Estimated dates of infection ranged from 21 to 60 days before enrollment. Median time to first detection ranged between 33 and 43 days, and most tests were reactive in all participants by 90 days after estimated date of infection (Table). For 3 individuals, the time of first detection was delayed 1 study visit (3 to 7 days) for the same test performed on fingerstick compared to whole blood. For the 2 tests performed on oral fluid, there was a median delay of 2 and 4 days for oral fluid compared to whole blood. However, 3 participants who initiated treatment prior to peak viremia remained negative on ≥1 oral fluid test through day 90 of follow-up. Conclusion: These are the first longitudinal data documenting seroconversion sensitivity of FDA-approved HIV tests performed on unprocessed specimens as intended for use in POC settings. These tests show a delay in earliest detection of 1 to 3 weeks when performed on these specimen types compared to previously published estimates using plasma. Because of the importance of POC tests, further improvements in seroconversion sensitivity and evaluations of new point-of-care tests using unprocessed specimens are warranted.

Poster Abstracts

CROI 2018 207