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Effect of lipemia and bilirubinemia on HIV-1 protease and reverse transcriptase genotyping and phenotyping success: a five-year analysis
© Pattery et al; licensee BioMed Central Ltd. 2010
Published: 8 November 2010
Interference of clinical laboratory assays by endogenous & exogenous substances in the blood is well known. To date, there are no clear guidelines on the testing of lipemic or bilirubinemic (icteric) plasma in clinical laboratories. A conservative approach of alerting the physician with re-sampling and/or processing with caution is advised. This study focuses on the effect of processed (2005-2010) HIV-1 lipemic or icteric patient plasma (visual inspection) on genotyping (virco®TYPE HIV-1) and phenotyping (Antivirogram®) success at Virco.
Materials and methods
The viral RNA extraction kits (QiaAmp Virus MDx kit: 965652 or Easymag Nuclisens: 280130-280135) are highly sensitive in deriving intact, good quality RNA from lipemic or icteric plasma, leading to successful amplification of PR- RT genes. The validity of the obtained result was confirmed by comparing the results from previous or subsequent visits/services from the same patient, where available.
Between 2005-2010, 569 lipemic (0.97% of total samples received) samples were processed. From the 510 genotype requests, 408 were successfully genotyped (positive & 265 had viral load (VL) >1000 cp/ml) and 102 failed (negative, 39 samples with VL <1000 cp/ml, 35 unknown VL & 28 with VL >1000 cp/ml). From the 335 phenotype requests, 267 were positive & 68 negative (36 with VL<1000 cp/ml, 16 unknown VL & 16 with VL >1000 cp/ml). From 2005-2010, 417 icteric (0.71% of total samples received) samples were processed. From the 394 genotype requests, 367 were positive (301 had VL >1000 cp/ml) & 27 negative (9 with VL<1000 cp/ml, 12 unknown VL & 6 with VL >1000 cp/ml). From the 166 phenotype requests, 153 were positive & 13 were negative (3 with VL<1000 cp/ml, 6 unknown VL & 4 with VL >1000 cp/ml).
No limitations were observed for the different Clades. The success rate for lipemic samples (265/293) & icteric samples (301/307) with VL >1000 cp/ml was 90% & 98% respectively, indicating that both lipemic and icteric samples can be processed for resistance testing using our genotyping and phenotyping assays, under circumstances where re-sampling is difficult. The sensitivity to phenotyping clearly demonstrates the integrity of the amplified product that can be used to generate viable recombinant virus stocks.
This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.