Antiviral Research 87 (2010) 367–372 Contents lists available at ScienceDirect Antiviral Research journal homepage: www.elsevier.com/locate/antiviral Tissue culture drug resistance analysis of a novel HIV-1 protease inhibitor termed PL-100 in non-B HIV-1 subtypes  Eugene L. Asahchop a,c,1 , Maureen Oliveira a,1 , Bluma G. Brenner a , Jorge L. Martinez-Cajas b , Thomas d’Aquin Toni a , Michel Ntemgwa a , Daniela Moisi a , Serge Dandache d , Brent Stranix d , Cecile L. Tremblay c , Mark A. Wainberg a,∗ a McGill University AIDS Centre, Lady Davis Institute, Jewish General Hospital, Montreal, Quebec, Canada b Queen’s University, Kingston, Ontario, Canada c Centre Hospitalier de l’Université de Montréal, Montréal, Québec, Canada d Ambrilia Biopharma Inc., Montreal, Quebec, Canada article info Article history: Received 5 March 2010 Received in revised form 31 May 2010 Accepted 1 June 2010 Keywords: HIV-1 subtypes Drug resistance Protease inhibition PL-100 abstract PL-100 is a novel HIV-1 protease inhibitor (PI) that maintains activity against viruses that are resistant to other PIs. To further characterize this compound, we used it to select for drug resistance in tissue culture, using two non-B HIV-1 subtypes, viz. subtype C and a CRF01 AE recombinant virus. PL-100 selected for both minor and major PI resistance mutations along either of two distinct pathways. One of these involved the V82A and L90M resistance mutations while the other involved a mutation at position T80I, with other mutations being observed at positions M46I/L, I54M, K55R, L76F, P81S and I85V. The resistance patterns in both subtype C and CRF01 AE were similar and an accumulation of at least three mutations in the flap and active sites were required in each case for high-level resistance to occur, demonstrating that PL-100 has a high genetic barrier against the development of drug resistance. © 2010 Elsevier B.V. All rights reserved. 1. Introduction The protease (PR) enzyme of human immunodeficiency virus type 1 (HIV-1) is an excellent therapeutic target since its inhibi- tion prevents the proteolytic processing of the Gag and Gag-Pol polyproteins (Ventoso et al., 2005). Protease inhibitors (PIs) are routinely prescribed for both treatment-naïve and experienced patients and have had a profound impact on HIV-associated disease progression, transmission, and morbidity and mortality (Palella et al., 1998). Drug resistance is a frequent complication in patients who fail therapy (Descamps et al., 2009; Luis Jimenez et al., 2005; Turner et al., 2005) and many studies have shown that drug-resistant viruses can be sexually transmitted (Aghokeng et al., 2009; Brenner et al., 2008). The problem of drug resistance is compounded by the worldwide dissemination of multiple different subtypes of HIV-1 and the fact that natural polymorphisms in both HIV-1 and HIV-2 can affect the emergence of drug resistance to cur-  Parts of these results were presented at the XVIII International HIV Drug Resis- tance Workshops, June 2009, Fort Myers, FL, USA. ∗ Corresponding author at: 3755 Cote-Ste-Catherine-Road, Montreal, Quebec, Canada H3T1E2. Tel.: +1 514 340 8260; fax: +1 514 340 7537. E-mail address: mark.wainberg@mcgill.ca (M.A. Wainberg). 1 Both the authors contributed equally to this work. rently approved drugs (Kantor and Katzenstein, 2003; Ntemgwa et al., 2007; Stranix et al., 2004). Furthermore, polymorphisms within the PR enzyme may not themselves be responsible for resistance but can contribute to the development of high-level resistance if other mutations are present (Bessong, 2008; Kantor and Katzenstein, 2003; Liu et al., 2007; Velazquez-Campoy et al., 2003; Vergne et al., 2000). It is therefore important to understand antiviral activity and drug resistance profiles in viruses of different subtypes. Recently, a novel PI termed PL-100 was shown to be active against both wild-type and drug-resistant forms of HIV-1 of sub- type B origin (Dandache et al., 2007). PL-100 is a lysine-based sulphonamide that was designed on the basis of subtype B PR struc- tural data (Stranix et al., 2004). Although PL-100 demonstrates a high genetic barrier for the development of drug resistance to sub- type B viruses (Dandache et al., 2008), little is known about the role that individual polymorphisms in some non-B subtypes might play in regard to the development of drug resistance (Kantor and Katzenstein, 2003; Liu et al., 2007; Ntemgwa et al., 2007). Here we describe in vitro development of resistance and the antiviral prop- erties of PL-100 against a panel of wild-type and drug-resistant non-B viruses. As examples of non-B subtypes we used subtype C and the circulating recombinant form (CRF) CRF01 AE that repre- sent the most prevalent subtype and CRF in circulation at this time (Hemelaar et al., 2006). 0166-3542/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.antiviral.2010.06.001