An "in-house" recombinant virus protease inhibitor susceptibility assay was carried out (median of 3 per @entity1 ) retrospectively in 26 @entity1 failing @entity645 protease inhibitor based therapy at regular intervals to the initiation of the first protease inhibitor. @entity1 were treated with either @entity5190 (N = 6), @entity486 (N = 10), or @entity485 (N = 10) and two @entity2353 analogues. Second line therapy was based on single or dual protease inhibitor regimens occasionally containing @entity5191 . Clinically relevant resistance cut-offs associated with a poorer virological outcome from 6 months on and the clinical outcome from 3 months on were determined tentatively as 4- to 8-fold resistance for @entity5190 and @entity486 and 2.5- to 8-fold to @entity485 . In addition, the degree of cross-resistance at the time of the change of protease inhibitor was associated with the response in viral load at 6 months to the second line therapy (P = 0.018). Cross-resistance (> or = 8-fold) between @entity486 and @entity5190 was common (78 and 100%). Cross-resistance between @entity5190 or @entity486 and @entity485 was less frequent (75 and 60% respectively) than the opposite (100%, P = 0.004). Cross-resistance to @entity5191 was encountered more frequently (> 70%) than to @entity5192 (9%). The magnitudes of resistance were correlated between each other. In summary, the protease inhibitor susceptibility carried out longitudinally appears to be an earlier prognostic marker than viral load in a context of cross-resistance. The magnitude of resistance, as a marker of cross-resistance, should be useful to guide second line therapy.

Longitudinal use of phenotypic resistance testing to HIV-1 protease inhibitors in XXXX developing HAART failure.

@entity1 :: ('9606', 'Species') :: ['Patients', 'patients', 'patient'] @entity5191 :: ('MESH:D019888', 'Chemical') :: ['nelfinavir'] @entity2353 :: ('CHEBI:33838', 'Chemical') :: ['nucleoside'] @entity5192 :: ('MESH:C095108', 'Chemical') :: ['amprenavir'] @entity5190 :: ('MESH:D019469', 'Chemical') :: ['indinavir'] @entity485 :: ('MESH:D019258', 'Chemical') :: ['saquinavir'] @entity645 :: ('57667', 'Species') :: ['HIV'] @entity486 :: ('MESH:D019438', 'Chemical') :: ['ritonavir']
@entity1 :: (9606,Species) :: ['patients']
