A new test developed by CDC could help researchers assess whether fewer people are becoming newly infected with HIV, thus whether a prevention program is working. At the 19th International AIDS Conference in Washington, Secretary of Health and Human Services Kathleen Sebelius called the Limiting Antigen Avidity Enzyme Immunoassay (LAAEI) “a major development that will help us better evaluate and improve our prevention efforts.”
LAAEI works by measuring how tightly an HIV antibody has bound to the HIV protein, said Dr. Bharat Parekh, laboratory director at CDC’s Center for Global Health (CGH), where the test was developed. He explained that the binding is weak when a person initially is infected but strengthens over time. LAAEI works on any HIV strain.
CDC trialed the test in Swaziland late last year, using both LAAEI and a traditional method of measuring incidence ahead of the implementation of a large-scale male circumcision program to prevent HIV. LAAEI analyzed blood samples from 6,000 people who had already tested HIV-positive to see how many had been recently infected. The traditional method, a longitudinal cohort estimate, involved analyzing blood samples from 12,000 HIV-negative males and females, and then retesting them six months later to see if any became infected.
LAAEI showed HIV incidence stood at 2.6 percent, while the longitudinal study result was 2.4 percent. However, LAAEI took 10 days and cost thousands of dollars, while the traditional method took two rounds of sampling six months apart and cost millions of dollars, said Yen Duong, a microbiologist with CGH’s HIV lab.
LAAEI, which is commercially available from Sedia Biosciences, now is being used in countries participating in the US President’s Emergency Plan for AIDS Relief program.
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