Clinical Implications of Identifying Non-B Subtypes of Human Immunodeficiency Virus Type 1 Infection [Walter EA, et al. CID 2000;31:798]: This is a report from U.S. military facilities concerning the implications of viral load testing in non-B subtypes of HIV. There were nine patients with non-B subtypes identified by physicians who were suspicious on the basis of low or undetectable HIV viral load tests using the Amplicor HIV-1 Monitor assay, version 1.0. Use of the 1.5 version detected a median viral load that was 2.0 log₁₀ RNA copies/mL higher.
Comment: The distribution of HIV subtypes is variable: for Africa the dominant subtypes are A, C, and D, for Southeast Asia it is subtype-E, for India it is subtype-C, and for the U.S. and Europe it is subtype-B. The problem with viral load testing using currently available assays seems to reside primarily with the 1.0 version of the Amplicor test. Clues to this possible problem include acquisition of HIV with foreign travel or a viral load that simply does not make sense.
posted 11/6/2000