1237. Selective HIV RNA screening of specimens that are non-reactive by 4th generation HIV testing can identify additional infections: lessons from the STOP Study
Session: Oral Abstract Session: HIV: Detection, Linkage, and Utilization
Saturday, October 5, 2013: 10:30 AM
Room: The Moscone Center: 250-262


FDA-approved 4th-generation combination HIV antigen/antibody immunoassays are highly sensitive for recent infection, but they may not diagnose very early HIV infection when only viral RNA is detectable. The Architect (Abbott) 4th-generation assay generates signal-to-cutoff ratios (S/CO) for each specimen tested; S/CO values < 1 are considered non-reactive. We examined pooled HIV RNA nucleic acid amplification testing (pNAAT) results for specimens with 4th-generation S/CO values < 1.


STOP is an on-going, prospective, within-individual study comparing the 4th-generation assay with pNAAT for detection of early HIV infection in participants with negative rapid HIV antibody tests. Sites include sexually transmitted disease clinics and community-based programs in New York City, San Francisco, and North Carolina. All participants have blood drawn for laboratory-based testing by both methods. We examined the proportion of HIV infections detected by pNAAT in 4th-generation non-reactive specimens (S/CO < 1) and calculated the number needed to test with supplemental RNA screening to detect one additional HIV infection for S/CO thresholds ranging from 0 to 0.999.


Between September 2011 and January 2013, 52,118 participants had non-reactive (S/CO <1) Architect results. Of these, 19 (0.04%) had HIV infection detected by pNAAT. Overall, 134 (0.26%) specimens from participants had a S/CO values between 0.7 – 0.999 and HIV infection was diagnosed in 6 (4.48%)[Figure]. At S/CO stratifications below 0.7, the percentage of individuals with HIV infection identified by RNA testing ranged from 0% to 0.14%. To detect one additional HIV infection, supplemental RNA testing would be required for 22.3 (95% CI: 10.4, 49.4) 4th-generation non-reactive specimens with a S/CO range of 0.7 - 0.999 and 83.5 (95% CI: 37.9, 185.5) specimens with a S/CO range of 0.5 - 0.999.


Detecting very early HIV infections is an essential step to prevent further HIV transmission and 4th-generation S/CO data can guide the use of RNA screening to detect these infections. This strategy would increase the sensitivity of 4th-generation-based HIV testing algorithms for very early HIV infection.

Nicholas J. Moss, MD, MPH, Alameda County Public Health Department, Oakland, CA, Charles Rose, PhD, Centers for Disease Control, Atlanta, GA, Cynthia L. Gay, MD, MPH, Medicine, University of North Carolina, Chapel Hill, NC, Laura Hall, MPH, ICF International, Atlanta, GA, Lisa B. Hightow-Weidman, MD, MPH, University of North Carolina, Chapel Hill, Chapel Hill, NC, Benjamin Tsoi, MD, MPH, Bureau of HIV/AIDS Prevention, New York City Department of Health and Mental Hygiene, Queens, NY, Emily Westheimer, MSc, Bureau of STD Prevention and Control, New York City Department of Health and Mental Hygiene, Queens, NY, Philip J. Peters, MD, Centers for Disease Control and Prevention, Atlanta, GA and Mark Pandori, PhD, San Francisco Department of Public Health, San Francisco, CA


N. J. Moss, None

C. Rose, None

C. L. Gay, None

L. Hall, None

L. B. Hightow-Weidman, None

B. Tsoi, None

E. Westheimer, None

P. J. Peters, None

M. Pandori, None

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