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- The Impact of HIV-1 Genetic Diversity in Maryland: Under Quantifying
"Non-B" Subtype HIV-1 Viral Loads with the FDA approved Assay.
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- R. MYERS*1, W. SZUCH1, V. NERURKAR2, S. ALEXANDER3, J. PATEL1, and J.
M. JOSEPH1.
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- 1Maryland Dept. of Hlth. Labs., Baltimore; 2Univ. of Hawaii at Manoa,
Honolulu; and 3Ortho-Clin. Diagnostics, Raritan, NJ.
Session 21. Poster
Molecular Epidemiology of HIV-1
Sunday, 12:30-1:30 pm
We have begun to recognize the emergence of Non-B HIV-1 subtypes in MD. It has been
reported that the standard FDA approved HIV-1 viral load assay [Roche Amplicor HIV-1
Monitor (RT/PCR)] under quantifies HIV-1 viral loads in some Non-subtype B HIV-1
infections. We identified 153 plasmas from 88 African expatriates attending a single HIV
treatment clinic in MD. It is highly possible that these individuals were infected with
Non-B HIV-1 subtypes outside of N. America. The HIV-1 viral loads of these samples had
been previously quantified in the approved (RT/PCR) assay. A retrospective study was
conducted, re-evaluating these samples in the Bayer Quantiplex HIV-1 v.3.0 (bDNA) assay to
assess the impact this potential HIV diversity could have on the accuracy HIV-1 testing in
our laboratory. No samples that had detectable HIV-1 viral burdens in the RT/PCR assay
failed to be detected in the bDNA assay. However, of the 57 samples that had low to
undetectable HIV-1 viral loads of <420 RNA copies/ml in the standard RT/PCR assay, 18
had > 1.0 log increases in HIV-1 viral burdens in the bDNA assay. The bDNA results
ranged from 1,979 to 94,107 HIV-1 RNA copies/ml (mean: 18,273 copies /ml). These samples
were collected from 11 individuals. To date six have been genotyped as HIV-1 subtype A.
One of these individuals is also co-infected with HIV-2. The under quantification of HIV-1
viral burdens could have an adverse impact on patient care. This study has illustrated the
need to use HIV-1 viral load assays that can detect viral burdens in Non-Subtype B HIV-1
infected individuals that are present in certain metropolitan areas of the US.
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