Comparison of Detection Limits of Fourth- and Fifth-Generation Combination HIV Antigen-Antibody, p24 Antigen, and Viral Load Assays on Diverse HIV Isolates.


Detection of acute HIV infection is critical for HIV public health and diagnostics. Clinical fourth-generation antigen (Ag)/antibody (Ab) combination (combo) and p24 Ag immunoassays have enhanced detection of acute infection compared to Ab-alone assays but require ongoing evaluation with currently circulating diverse subtypes. Genetically and geographically diverse HIV clinical isolates were used to assess clinical HIV diagnostic, blood screening, and next-generation assays. Three-hundred-member panels of 20 serially diluted well-characterized antibody-negative HIV isolates for which the researchers were blind to the results (blind panels) were distributed to manufacturers and end-user labs to assess the relative analytic sensitivity of currently approved and preapproved clinical HIV fourth-generation Ag/Ab combo or p24 Ag-alone immunoassays for the detection of diverse subtypes. The limits of detection (LODs) of virus were estimated for different subtypes relative to confirmed viral loads. Analysis of immunoassay sensitivity was benchmarked against confirmed viral load measurements on the blind panel. On the basis of the proportion of positive results on 300 observations, all Ag/Ab combo and standard sensitivity p24 Ag assays performed similarly and within half-log LODs, illustrating the similar breadth of reactivity and diagnostic utility. Ultrasensitive p24 Ag assays achieved dramatically increased sensitivities, while the rapid combo assays performed poorly. The similar performance of the different commercially available fourth-generation assays on diverse subtypes supports their use in broad geographic settings with locally circulating HIV clades and recombinant strains. Next-generation preclinical ultrasensitive p24 Ag assays achieved dramatically improved sensitivity, while rapid fourth-generation assays performed poorly for p24 Ag detection.





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Stone, Mars, John Bainbridge, Ana M Sanchez, Sheila M Keating, Andrea Pappas, Wes Rountree, Chris Todd, Sonia Bakkour, et al. (2018). Comparison of Detection Limits of Fourth- and Fifth-Generation Combination HIV Antigen-Antibody, p24 Antigen, and Viral Load Assays on Diverse HIV Isolates. Journal of clinical microbiology, 56(8). 10.1128/jcm.02045-17 Retrieved from

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Thomas Norton Denny

Professor in Medicine

Thomas N. Denny, MSc, M.Phil, is the Chief Operating Officer of the Duke Human Vaccine Institute (DHVI), Associate Dean for Duke Research and Discovery @RTP, and a Professor of Medicine in the Department of Medicine at Duke University Medical Center. He is also an Affiliate Member of the Duke Global Health Institute. Previously, he served on the Health Sector Advisory Council of the Duke University Fuquay School of Business. Prior to joining Duke, he was an Associate Professor of Pathology, Laboratory Medicine and Pediatrics, Associate Professor of Preventive Medicine and Community Health and Assistant Dean for Research in Health Policy at the New Jersey Medical School, Newark, New Jersey. He has served on numerous committees for the NIH over the last two decades and currently is the principal investigator of an NIH portfolio in excess of 65 million dollars. Mr. Denny was a 2002-2003 Robert Wood Johnson Foundation Health Policy Fellow at the Institute of Medicine of the National Academies (IOM). As a fellow, he served on the US Senate Health, Education, Labor and Pensions Committee with legislation/policy responsibilities in global AIDS, bioterrorism, clinical trials/human subject protection and vaccine related-issues.

As the Chief Operating Officer of the DHVI, Mr. Denny has senior oversight of the DHVI research portfolio and the units/teams that support the DHVI mission. He has extensive international experience and previously was a consultant to the U.S. Centers for Disease Control and Prevention (CDC) for the President’s Emergency Plan for AIDS Relief (PEPFAR) project to oversee the development of an HIV and Public Health Center of Excellence laboratory network in Guyana. In September 2004, the IOM appointed him as a consultant to their Board on Global Health Committee studying the options for overseas placement of U.S. health professionals and the development of an assessment plan for activities related to the 2003 PEPFAR legislative act. In the 1980s, Mr. Denny helped establish a small laboratory in the Republic of Kalmykia (former Soviet Union) to improve the care of children with HIV/AIDS and served as a Board Member of the Children of Chernobyl Relief Fund Foundation. In 2005, Mr. Denny was named a consulting medical/scientific officer to the WHO Global AIDS Program in Geneva. He has also served as program reviewers for the governments of the Netherlands and South Africa as well as an advisor to several U.S. biotech companies. He currently serves as the Chair of the Scientific Advisory Board for Grid Biosciences.

Mr. Denny has authored and co-authored more than 200 peer-reviewed papers and serves on the editorial board of Communications in Cytometry and Journal of Clinical Virology. He holds an M.Sc in Molecular and Biomedical Immunology from the University of East London and a degree in Medical Law (M.Phil) from the Institute of Law and Ethics in Medicine, School of Law, University of Glasgow. In 1991, he completed a course of study in Strategic Management at The Wharton School, University of Pennsylvania. In 1993, he completed the Program for Advanced Training in Biomedical Research Management at Harvard School of Public Health. In December 2005, he was inducted as a Fellow into the College of Physicians of Philadelphia, the oldest medical society in the US.

While living in New Jersey, Mr. Denny was active in his community, gaining additional experience from two publicly elected positions. In 2000, Mr. Denny was selected by the New Jersey League of Municipalities to Chair the New Jersey Community Mental Health Citizens’ Advisory Board and Mental Health Planning Council as a gubernatorial appointment.

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