A method for monitoring ARV resistance, to determine viral fitness, and to forecastpossible drug failure utilizes two nucleic acid sequences. One nucleic acidincludes a retroviral nucleic acid devoid of at least a majority of the sequencefor one of the two long terminal repeat regions. A second nucleic acid, includesa retroviral nucleic acid sequence devoid of the sequences encoding an envelopegene and the second long terminal repeat region of the retrovirus. The methodallows the rapid cloning of an amplicon into an HIV-1 genome vector through recombination/gaprepair in organisms such as yeast. The vectors can be directly passed to a mammaliancell line which has been specifically engineered to produce replication competentHIV-1 particles. The susceptibility of an isolate to any of several ARVs, i.e.PRIs, NRTIs, NNRTIs, T20, as well as entry and integrase inhibitors in development/clinicaltrials, may be tested.
