Tipranavir resistance associated mutations in protease inhibitor-naïve patients with HIV-1 subtype A/E infection

Potential Resistance of SARS-CoV-2 Main Protease (Mpro) against Protease Inhibitors: Lessons Learned from HIV-1 Protease

Coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome 2 (SARS-CoV-2), has been one of the most devastating pandemics of recent times. The lack of potent novel antivirals had led to global health crises; however, emergence and approval of potent inhibitors of the viral main protease (Mpro), such as Pfizer's newly approved nirmatrelvir, offers hope not only in the therapeutic front but also in the context of prophylaxis against the infection. By their nature, RNA viruses including human immunodeficiency virus (HIV) have inherently high mutation rates, and lessons learnt from previous and currently ongoing pandemics have taught us that these viruses can easily escape selection pressure through mutation of vital target amino acid residues in monotherapeutic settings. In this paper, we review nirmatrelvir and its binding to SARS-CoV-2 Mpro and draw a comparison to inhibitors of HIV protease that were rendered obsolete by emergence of resistance mutations, emphasizing potential pitfalls in the design of inhibitors that may be of important relevance to the long-term use of novel inhibitors against SARS-CoV-2.

Characterization of protease resistance-associated mutations in HIV type 1 drug-naive patients following the increasing prevalence of the CRF02_AG strain in Morocco

The purpose of this study was to investigate the amino acid substitutions in the protease of HIV-1 B and non-B subtypes and evaluate whether the emergence of resistance-associated mutations (RAMs) could have a significant correlation with the increasing prevalence of CRF02_AG strains in Morocco. A total of 162 protease gene sequences were successfully amplified from drug-naive HIV-1-infected individuals. We identified eight (sub)subtypes and CRFs: B(66%), A1(3.7%), C(1.2%), F1(0.6%), F2(0.6%), G(1.2%), CRF02_AG(25.3%), and CRF01_AE(1.2%). Phylogenetic analysis of CRF02_AG strains showed that 9.8% of isolates had a closer connection with reference strains from Morocco and 15.4% clustered with reference strains from eight West African and three European countries. When compared to the B subtype, patients with the CRF02_AG strain had a significantly higher prevalence of mutations associated with resistance to some antiprotease drugs, mainly tipranavir (TPV): H69K (97% vs. 5%; p<0.0001), L89M (95% vs. 1%; p<0.0001), and M36I/L (93% vs. 44%; p<0.0001). Most of the CRF02_AG strains (97%) significantly showed at least two TPV-RAMs (p=0.002) compared to the B subtype (7%). Multivariate analysis revealed that CRF02_AG infection was the only factor highly associated with the occurrence of more than two TPV-RAMs (C=0.42; p<0.0001). These results support the importance of transmitted drug resistance mutations (M36I/L, H69K, and L89M) in the protease gene of HIV-1 CRF02_AG isolates. This HIV drug resistance transmission before protease inhibitor (PI) exposure raises concern about its influence on the susceptibility of CRF02_AG strains to some PIs, especially tipranavir, which will soon be introduced as part of the second line therapeutic regimens in Morocco.

Comparison of drug resistance scores for tipranavir in protease inhibitor-naive patients infected with HIV-1 B and non-B subtypes

Genotypes of samples from protease inhibitor-naïve patients in Frankfurt's HIV Cohort were analyzed with five tipranavir resistance prediction algorithms. Mean scores were higher in non-B than in B subtypes. The proportion of non-B subtypes increased with increasing scores, except in weighted algorithms. Virtual and in vitro phenotype analyses of samples with increased scores showed no reduced tipranavir susceptibility. Current algorithms appear suboptimal for interpretation of resistance to tipranavir in non-B subtypes; increased scores might reflect algorithm bias rather than "natural resistance."

Low prevalence of drug resistance transmitted virus in HIV Type 1-infected ARV-naive patients in Cambodia

Abstract Between November 2006 and June 2007, HIV-1 reverse transcriptase (RT) and protease (PR) genes of 67 ARV-naive Cambodian patients were amplified and sequenced. At inclusion, the median age and duration of HIV infection were 28 and 1.1 years, respectively. The median CD4 and HIV-1 RNA were 611 cells/ml [IQR: 525-759] and 4.0 log(10) copies/ml [IQR: 3.4-4.6]. Among 67 HIV-1 strains, 95.5% were CRF 01_AE viruses (n = 64) whereas three clustered with subtype B. RT analysis indicated that only 1 patient out of 67, presenting K103N and M184V mutations, was resistant to NVP/EFV and 3TC/FTC. No primary resistance to protease inhibitors was detected in 59 amplified protease genes. The 1.49% (IC 95%: 0.04-8.04%) prevalence of transmitted drug-resistant strains in drug-naive patients was low in our study. Surveys of drug-resistant transmitted viruses should be regularly performed regarding the increasing access to HAART in Cambodia.