ADDITIONAL MUTATIONS DETECTED IN SEQUENTIAL HIV-1 ISOLATES FROM ZDV-TREATED PATIENTS

Sequential isolates from four patients under zidovudine (ZDV) therapy were obtained using PBMC coculture in the absence or in the presence o f 0.25 mu M ZDV. PBMC-based HIV susceptibility assay demonstrated the emergence of ZDV-resistance in the sequential isolates from the four p atients, Except in one case, the isolates obtained in the presence of ZDV did not exhibit a greater resistance pattern than their counterpar ts obtained in the absence of the drug. In parallel, partial reverse t ranscriptase gene sequence was determined directly on amplified produc ts from proviral DNA. In addition to the mutations previously describe d at the critical codons 41, 67, 70, 215, and 219, numerous additional mutations were found in either ZDV-sensitive or ZDV-resistant isolate s, The mutation Thr215Tyr was not observed in a case-of highly resista nt virus ZDV IC50 > 6.25 mu M), while the mutation Lys70Arg was found in either resistant or sensitive-ones. The analysis oi additional muta tions did not reveal any clear pattern for ZDV resistance but pointed out the existence of highly variable regions neighbouring the five cri tical codons. Nei ther nucleotide sequence: nor PBMC-based sus ceptibi lity assay provided unambiguous data a bout pretherapy isolates or ear ly on-therapy isolates which could predict the emergence of ZDV resist ance in further samples. (C) 1997 Wiiey-Liss, Inc.