Variant HIV Subtypes on the Rise

An ongoing concern for public health authorities and infectious disease experts is the ability of deadly pathogens to adapt or mutate and become difficult to detect and treat. One of the more clever bugs is the HIV virus, which has numerous strains and subtypes that may elude detection. The problem has intensified as the world continues to shrink.

Many studies have reported that the growing population of immigrants from countries where variant strains are more common has caused a significant increase in newly diagnosed HIV patients infected with variant, possibly drug-resistant strains.

Recently, the New England Journal of Medicine published a study by Columbia University researchers which concludes: “The continuing spread of HIV is causing a world pandemic of unprecedented genetic and geographic complexity. Five HIV subtypes and two circulating recombinant forms have each established a global prevalence greater than 2.5 percent, a level that virtually ensures continued presence in the decades to come.”

Further, the Centers for Disease Control and Prevention (CDC) has reported the estimated prevalence of variant HIV subtypes is about 5 percent. Variant strains of HIV-1 originating in Africa, Asia and Latin America are being detected with greater frequency in the United States, especially New York City and other areas with immigrants from continents where variant subtypes predominate. A major concern is most diagnostic test reagents for HIV have been engineered for the most common HIV subtype B, but due to immigration and frequent international travel the regional balance of HIV subtypes is shifting.

Optimal treatment of HIV infection depends on accurate measurement of viral levels. Patients taking anti-viral drugs to control their HIV infections, therefore, may not be treated effectively if variant HIV subtypes are present. Ongoing, precise measurement of viral levels is required for drug treatment to be effective, and if variant HIV subtypes are present and significantly under-quantified or undetected, therapy could be compromised.

Based on results of several studies, current molecular based diagnostic tests vary in their ability to detect and reliably quantify variant strains of HIV-1 and have been found to under-quantify them.

Source: Abbott Molecular