Two rapid complementary methods to detect progressive zidovudine resistance mutations in mononuclear cells of...

The objective of the study was to evaluate a rapid screening technique for the presence of mutations in the viral reverse transcriptase gene of HIV following prolonged therapy with zidovudine in patients with AIDS. Peripheral blood mononuclear cells (PBMCs) of 14 HIV-infected patients were analyzed by micro-titer point mutation assay (PMA) before therapy with zidovudine and after at least 10 months of treatment. In addition, five of these were analyzed longitudinally. Three nontreated HIV-seropositive individuals were tested as controls. To confirm the validity of the PMA, patients' material was also analyzed with the single strand conformational polymorphism (SSCP) assay. After 10-55 months of treatment, at codons 41, 70, and 215 a shift from predominantly wild type strains to a mixture of wild type and mutant strains (21%-100% mutant sequences) appeared in the majority of patients' PBMCs. At codons 67 and 219, the wild type strain persisted after therapy in all but 3 patients. Most mutations were detected by SSCP as well as by PMA, except for one mutation at codon 41 and one at codon 70. However, when the two mutations were both present, SSCP and PMA were both able to detect these mutations. In conclusion, both PMA and SSCP are rapid and simple methods for screening for mutations causing drug resistance in zidovudine-treated HIV-infected patients. Although PMA is more labor-extensive than SSCP, the advantage of PMA over SSCP is that it permits the quantitative detection of point mutations coding for zidovudine resistance. The application of these assays may improve procedures of monitoring and modifying antiretroviral therapy on an individual basis.