New Study Evaluates Sensitivity of HIV Screening Tests

The human immunodeficiency virus (HIV) was responsible for the deaths of approximately 1.1 to 1.3 million individuals in 2015. The World Health Organization (WHO) estimates that there were approximately 40 million individuals living with HIV at the end of 2015. Only 60% of HIV-positive individuals know of their infection status; the remaining 40%, which amount to approximately 14 million individuals, are unaware of their status and can unknowingly transmit the virus.

For individuals at high risk of acquiring HIV, the WHO recommends pre-exposure prophylaxis (PrEP), which is the daily use of antiretroviral drugs by HIV-negative individuals to prevent transmission. Individuals are typically tested for HIV before beginning PrEP, and are continually monitored as they continue to take antiretroviral drugs. Participants are usually screened for HIV through antigen/antibody immunoassays or through antibody rapid tests, both of which are serological tests that detect if antibodies produced in response to HIV antigens are present.

In a new study published in the Oxford University Press, lead investigator Constance Delaugerre, PharmD, PhD, and her colleagues, sought to evaluate the effectiveness of multiple HIV diagnostic tests. Participants consisted of patients in the ANRS IPERGAY study which was a randomized, double-blind PrEP trial for men who have sex with men (MSM), a group considered high-risk for infection. The authors evaluated two antigen/antibody immunoassay tests, ARCHITECT and BIOPLEX, and three antibody rapid tests, VIKIA, AUTOTEST, and ALERE. The patients were classified into 3 groups using HIV-1 western blot (WB): those with no detectable antibody, those with 1 to 6 antibodies (labeled as incomplete), and those with 7 or more antibodies (labeled as complete). The sensitivity of each test was determined by the percentage of positive results among all the HIV-positive samples as determined by HIV-1 RNA load, as well as the ARCHITECT test.

Among the 478 MSM in the IPERGAY trial, 31 patients were diagnosed as HIV-positive, with 10 patients being diagnosed at the onset of the trial, and 21 patients who acquired HIV during the trial. For the antigen/antibody immunoassay tests, the sensitivity of both tests was 100% for patients with incomplete as well as complete WB. For the 13 patients with negative WB, the ARCHITECT test was positive in 11 out of 14 cases, while the BIOPLEX test was positive in 8 patients. However, there was no statistically significant difference in sensitivity between the two tests.

For the antibody rapid tests, sensitivity was 100% for patients with complete WB. However, for patients with incomplete WB, ALERE was found to be the most sensitive (100%), followed by AUTOTEST (88%), and VIKIA (75%). A similar trend was observed for patients with negative WB, with ALERE being the most sensitive (54%), followed by VIKIA (15%), and AUTOTEST (0%). The difference in sensitivity between ALERE and the other two antibody rapid tests was found to be statistically significant.

Overall, this work raises awareness about the need for reliable HIV screening, and the importance of screening regularly during PrEP to avoid missing cases of acute HIV infection. This is critical, as it will lessen the risk of viral transmission among HIV-positive individuals who are unaware of their infection status and will also prevent the development of drug resistance.

Samar Mahmoud graduated from Drew University in 2011 with a BA in Biochemistry and Molecular Biology. After two years of working in industry as a Quality Control Technician for a blood bank, she went back to school and graduated from Montclair State University in 2016 with an MS in Pharmaceutical Biochemistry. She is currently pursuing her PhD in Molecular and Cellular Biology at the University of Massachusetts at Amherst.