How accurate are HIV antibody tests in detecting the various subtypes of HIV-1?
A. HIV-1 is divided into two groups of subtypes. These two groups are referred to as Group M (major) and Group O (outlier). HIV-1 subtypes of Group M vary, depending on their genetic structure. These include subtypes A through I. In the United States, the predominate HIV-1 subtype is B. Most antibody tests for detecting HIV-1 were developed with the B subtype of the virus. As the genetic composition of a particular virus diverges from the B subtype, the likelihood that the test will be accurate decreases. Most tests, however, do appear to be able to detect antibody to most strains. There are many reasons for a false-positive EIA result. Some of the more common are Contamination: In a laboratory, samples may be placed in the wrong testing well; wells containing negative samples may be contaminated from adjacent positive wells; plate washers may malfunction. In addition, treated blood and blood abnormalities have been implicated in false positive reactions. • False positive reactions hav
