Among the MPS data analyzed

Among the 84 MPS data analyzed by g2p algorithm2.5%, the CXCR4-using viruses were predicted in 13 (15.5%). Also, a higher rate (14.3%) of CXCR4-using viruses was observed among the LS group in this study. These results were comparable to our previous study [9], which reported a relatively high frequency (13.3%) of CXCR4-using viruses in 45 HIV-1 recently infected donors, despite the fact that they were based on different FPR algorithms (>3.5% and >2.5%). Our results can also be compared with those reported in drug-naive chronically HIV-infected individuals [27] and in suppressed patients with a shorter history of viremia suppression [24]. In contrast, our prevalence estimates of CXCR4-using viruses are nearly five times higher than those found among recently infected men having sex with men in the USA [28] and almost half the prevalence rate reported in recently infected Brazilian subjects [16]. Factors like size and type of samples, the sequencing method, the FPR cutoff, stage of HIV infection (primary vs chronic infection), and prediction algorithms used may have contributed to these differences. Studies like ours that based on MPS data generally detect more CXCR4 variants compared to the conventional genotypic sequencing technologies. For instance, of the 84 studied subjects, our study was able to detect seven subjects (8.3%) with X4 minority variants (fewer than 20% abundance) that would likely have been missed if standard population-based sequencing data had been used alone. Thus, the application of deep sequencing technology has significantly improved the prediction of HIV tropism as has been reported in previous studies [9,21]. Detection of R5×4 mixed infection in this study could be either the result of direct transmission of both variants, successive infections within a short timeframe, or a rapid switch from CCR5-using to CXCR4-using virus shortly after transmission. The hypothesis of direct transmission of both variants could result from a stochastic process as has been suggested previously [29]. Because CXCR4-using viruses are more pathogenic than R5 viruses [30], larger studies are needed to confirm the negative impact of these variants on the subsequent PF-3758309 of HIV-1 disease and to investigate the efficiency of these variants to influence the patient׳s response to CCR5 antagonists. We acknowledge that our study had a number of limitations that should be highlighted. The most important limitation is that the assessment of HIV tropism was limited to sequence-based algorithms rather than phenotypic methods. Although phenotypic assays still have an edge over genotypic methods, Ultra-deep sequencing data prove to be highly concordant with phenotype data for determining HIV-1 co-receptor use during primary HIV infection [31] and can reliably be used to determine viral tropism with better results in PBMC than in plasma samples [32]. Other limitations include small sample size and relatively low sequencing coverage (500X). Also, our V3 MPS data were derived from specific groups of HIV-1 infected first-time blood donors and the results may not reflect the prevalence in the general populations.
Conclusions
Competing interests
Authors׳ contributions
Data These data are the annotated hits identified by screening both detergent-solubilised (DS) and lipid-reconstituted (LR) respiratory Type II NADH dehydrogenase. The table contains the library; compound name, number of H-bond donors/acceptors, molecular weight, lipophilicity (logP) and degree of inhibition/stimulation for DS and LR protein (Table 1).
Experimental design, materials and methods Type II NADH dehydrogenase (NDH-2) was purified and reconstituted into proteoliposomes as described by Dunn et al. [2,3]. Detergent-solubilised (DS) NDH-2 or lipid-reconstituted (LR) NDH-2 were screened by end point 96-well assay (340nm, Varioskan® Flash Thermo Scientific, in the presence of 100μM menadione and 20μM test compound. The reaction was initiated using 200μM NADH. Screening was carried out in technical triplicate against each compound library. NADH: menadione oxidoreductase inhibition/stimulation was calculated as a percentage of control activity for either DS or LR protein [2]. Compounds showing inhibition (≤70% control) or activation (≥130% control) in at least 2 of the 3 independent screening replicates were considered hits. Compound libraries screened were Library of Pharmacologically Active Compounds (LOPAC, SigmaAldrich), the Natural Products Set II (National Institutes of Health, USA) and the Quinolinequinone Library (Malaghan Institute of Medical Research, NZ) [4]. Hits were annotated with library of origin, chemical name and the drug-like properties governing in vivo absorption as described by the ‘Rule of Five’ namely, lipophilicity (logP), molecular weight, hydrogen bond donor and hydrogen bond acceptors [5]. Where necessary logP was predicted using ALOGPS software provided by the Virtual Computational Chemistry Laboratory [6].