Search

Background Treatment of Plasmodium vivax malaria requires the clearing of asexual parasites, but relapse can be prevented only if dormant hypnozoites are cleared from the liver (a treatment termed “radical cure”). Tafenoquine is a single-dose 8-aminoquinoline that has recently been registered for the radical cure of P. vivax. Methods This multicenter, double-blind, double-dummy, parallel group, randomized, placebo-controlled trial was conducted in Ethiopia, Peru, Brazil, Cambodia, Thailand, and the Philippines. We enrolled 522 patients with microscopically confirmed P. vivax infection (>100 to Results In the intention-to-treat population, the percentage of patients who were free from recurrence at 6 months was 62.4% in the tafenoquine group (95% confidence interval [CI], 54.9 to 69.0), 27.7% in the placebo group (95% CI, 19.6 to 36.6), and 69.6% in the primaquine group (95% CI, 60.2 to 77.1). The hazard ratio for the risk of recurrence was 0.30 (95% CI, 0.22 to 0.40) with tafenoquine as compared with placebo (P Conclusions Single-dose tafenoquine resulted in a significantly lower risk of P. vivax recurrence than placebo in patients with phenotypically normal G6PD activity. (Funded by GlaxoSmithKline and Medicines for Malaria Venture; DETECTIVE ClinicalTrials.gov number, NCT01376167. opens in new tab.)

Tafenoquine is an 8-aminoquinoline under investigation for the prevention of relapse in Plasmodium vivax malaria. This open-label, dose-escalation study assessed quantitatively the hemolytic risk with tafenoquine in female healthy volunteers heterozygous for the Mahidol 487A glucose-6-phosphate dehydrogenase (G6PD)-deficient variant versus G6PD-normal females, and with reference to primaquine. Six G6PD-heterozygous subjects (G6PD enzyme activity 40–60% of normal) and six G6PD-normal subjects per treatment group received single-dose tafenoquine (100, 200, or 300 mg) or primaquine (15 mg × 14 days). All participants had pretreatment hemoglobin levels ≥ 12.0 g/dL. Tafenoquine dose escalation stopped when hemoglobin decreased by ≥ 2.5 g/dL (or hematocrit decline ≥ 7.5%) versus pretreatment values in ≥ 3/6 subjects. A dose–response was evident in G6PD-heterozygous subjects (N = 15) receiving tafenoquine for the maximum decrease in hemoglobin versus pretreatment values. Hemoglobin declines were similar for tafenoquine 300 mg (−2.65 to −2.95 g/dL [N = 3]) and primaquine (−1.25 to −3.0 g/dL [N = 5]). Two further cohorts of G6PD-heterozygous subjects with G6PD enzyme levels 61–80% (N = 2) and > 80% (N = 5) of the site median normal received tafenoquine 200 mg; hemolysis was less pronounced at higher G6PD enzyme activities. Tafenoquine hemolytic potential was dose dependent, and hemolysis was greater in G6PD-heterozygous females with lower G6PD enzyme activity levels. Single-dose tafenoquine 300 mg did not appear to increase the severity of hemolysis versus primaquine 15 mg × 14 days.

Tafenoquine is an 8-aminoquinoline under investigation for the prevention of relapse in Plasmodium vivax malaria. This open-label, dose-escalation study assessed quantitatively the hemolytic risk with tafenoquine in female healthy volunteers heterozygous for the Mahidol487A glucose-6-phosphate dehydrogenase (G6PD)-deficient variant versus G6PD-normal females, and with reference to primaquine. Six G6PD-heterozygous subjects (G6PD enzyme activity 40–60% of normal) and six G6PD-normal subjects per treatment group received single-dose tafenoquine (100, 200, or 300 mg) or primaquine (15 mg × 14 days). All participants had pretreatment hemoglobin levels ≥ 12.0 g/dL. Tafenoquine dose escalation stopped when hemoglobin decreased by ≥ 2.5 g/dL (or hematocrit decline ≥ 7.5%) versus pretreatment values in ≥ 3/6 subjects. A dose–response was evident in G6PD-heterozygous subjects (N = 15) receiving tafenoquine for the maximum decrease in hemoglobin versus pretreatment values. Hemoglobin declines were similar for tafenoquine 300 mg (−2.65 to −2.95 g/dL [N = 3]) and primaquine (−1.25 to −3.0 g/dL [N = 5]). Two further cohorts of G6PD-heterozygous subjects with G6PD enzyme levels 61–80% (N = 2) and > 80% (N = 5) of the site median normal received tafenoquine 200 mg; hemolysis was less pronounced at higher G6PD enzyme activities. Tafenoquine hemolytic potential was dose dependent, and hemolysis was greater in G6PD-heterozygous females with lower G6PD enzyme activity levels. Single-dose tafenoquine 300 mg did not appear to increase the severity of hemolysis versus primaquine 15 mg × 14 days.

BACKGROUND: Clinical effectiveness of previous regimens to treat Plasmodium vivax infection have been hampered by compliance. We aimed to assess the dose-response, safety, and tolerability of single-dose tafenoquine plus 3-day chloroquine for P vivax malaria radical cure. METHODS: In this double-blind, randomised, dose-ranging phase 2b study, men and women (aged >/=16 years) with microscopically confirmed P vivax monoinfection (parasite density >100 to 7500 per muL blood). The primary efficacy endpoint was relapse-free efficacy at 6 months from initial dose (ie, clearance of initial infection without subsequent microscopically confirmed infection), analysed by intention to treat. This study is registered with ClinicalTrials.gov, number NCT01376167. FINDINGS: Between Sept 19, 2011, and March 25, 2013, 329 patients were randomly assigned to a treatment group (chloroquine plus tafenoquine 50 mg [n=55], 100 mg [n=57], 300 mg [n=57], 600 mg [n=56]; or to chloroquine plus primaquine [n=50]; or chloroquine alone [n=54]). Relapse-free efficacy at 6 months was 57.7% (95% CI 43-70) with tafenoquine 50 mg, 54.1% (40-66) with tafenoquine 100 mg, 89.2% (77-95) with tafenoquine 300 mg, 91.9% (80-97) with tafenoquine 600 mg, 77.3% (63-87) with primaquine, and 37.5% (23-52) with chloroquine alone. Tafenoquine 300 mg and 600 mg had better efficacy than chloroquine alone (treatment differences 51.7% [95% CI 35-69], p

The selection of drug resistant viruses is a major problem in efforts to combat HIV and AIDS, hence, new compounds are required. We report crystal structures of wild-type and mutant HIV-1 RT with bound non-nucleoside (NNRTI) GW420867X, aimed at investigating the basis for its high potency and improved drug resistance profile compared to the first-generation drug nevirapine. GW420867X occupies a smaller volume than many NNRTIs, yet accesses key regions of the binding pocket. GW420867X has few contacts with Tyr188, hence, explaining the small effect of mutating this residue on inhibitor-binding potency. In a mutated NNRTI pocket, GW420867X either remains in a similar position compared to wild-type (RT(Leu100Ile) and RT(Tyr188Cys)) or rearranges within the pocket (RT(Lys101Glu)). For RT(Leu100Ile), GW420867X does not shift position, in spite of forming different side-chain contacts. The small bulk of GW420867X allows adaptation to a mutated NNRTI binding site by repositioning or readjustment of side-chain contacts with only small reductions in binding affinity.

Drug susceptibility phenotyping of recombinant clinical human immunodeficiency virus type 1 (HIV-1) isolates has been used widely to quantitatively assess viral resistance to antiretroviral agents. A novel method is described for HIV-1 drug susceptibility phenotyping. Recombinant virus that contains the entire HIV-1 Gag, protease (PR) and reverse transcriptase (RT) coding regions is generated from plasma of HIV-1 infected subjects, thus allowing the in vitro investigation of effects caused by all protein-coding sequence elements upstream from the drug targets on: (i) drug susceptibility; and (ii) viral replicative capacity. Mutations known to cause retarded viral growth kinetics (RT M184V and PR I50V) were introduced and analyzed in parallel using both the new Five Prime HIV assay (FPH) and a standard recombinant virus assay (RVA). The M184V and I50V mutants produced up to 4.8- and 5.9-fold higher p24 antigen levels, respectively, with the FPH when compared to the cultures containing RVA-derived viruses. The reduced number of homologous recombination events necessary to generate replication-competent provirus with the FPH is the most likely explanation for these findings. Long range RT-PCR products were generated from plasma of HIV-1 infected subjects and HIV-1 LTR sequences were added using one-step PCR-mediated recombination. FPH-recombinants generated from two patients with previous HIV PR and RT inhibitor therapy showed lower drug susceptibilities than mutants established in parallel by RVA, and relative in vitro replication of the FPH recombinant derived from one of these subjects was enhanced compared to the corresponding RVA mutant. Although there were changes from the HIV-1 subtype B consensus sequence in amino acids flanking the Gag p17/p24, p24/p2 or p2/p7 PR cleavage sites, none were within the 10 amino acids immediately flanking the sites. These data suggest that determinants of drug susceptibility may be encoded in Gag upstream of the p7/p1 and p1/p6 regions, and that some phenotyping assays may therefore be underdetermining the reduction of drug susceptibility in some viral isolates.

GW420867X is a nonnucleoside inhibitor of HIV-1 reverse transcriptase. The primary objective was to assess the safety of GW420867X in HIV-1-infected patients. The secondary objectives were to assess the effect of GW420867X on plasma HIV-1 RNA and viral genotype and phenotype and to examine the pharmacokinetics of GW420867X in HIV-1-infected patients.HIV-1-infected patients were randomized to GW420867X 50 mg/day, 100 mg/day, or 200 mg/day from days 1-28 (n = 15 per group). Lamivudine (3TC) plus zidovudine (ZDV) was added from days 8-28. A control group (n = 15) received GW420867X, 3TC, and ZDV placebos.Plasma HIV-1 RNA and CD4+ counts improved in the GW420867X groups at days 8 and 28. No significant development of drug resistance was detected. Median observed peak GW420867X concentration (C(max)) generally occurred at 2 hours. The area under the curve over the dosing interval (AUCtau)on day 14 increased less than proportionally to dose, suggesting there was increased clearance and/or decreased absorption. Mean trough GW420867X concentrations were many fold above the in vitro IC(50) in the presence of human serum proteins. Seven of 15 patients on 50 mg GW420867X, 8/15 on 100 mg GW420867X, 12/15 on 200 mg GW420867X, and 8/15 on placebo reported drug-related adverse events.GW420867X was well tolerated and has potent antiretroviral activity alone and in combination with 3TC plus ZDV.

Objectives To assess the role of resistance mutations in subjects experiencing virological failure on zidovudine (ZDV) and lamivudine (3TC) combined with a protease inhibitor (PI) to those failing on ZDV/3TC alone. Design and methods Samples were obtained from previously antiretroviral therapy-naive subjects enrolled into two studies, AVANTI 2 and AVANTI 3. Subjects were randomized to receive either: ZDV/3TC or ZDV/3TC plus indinavir (IDV) for 52 weeks (AVANTI 2), and ZDV/3TC or ZDV/3TC and nelfinavir (NFV) for 28 weeks (AVANTI 3). Emergence of viral resistance mutations was monitored by population sequencing and phenotypic resistance was determined by the recombinant virus assay. Results Genotypic data were obtained for subjects with plasma HIV-1 RNA > 400 copies/ml. In AVANTI 2, ZDV mutations were detected in 27% of ZDV/3TC-treated patients at week 52, but were absent in subjects treated with ZDV/3TC/IDV. No subjects from either arm of AVANTI 3 developed ZDV resistance mutations at week 28. The M184V mutation developed in most ZDV/3TC-treated subjects from both studies. The presence of M184V was, however, associated with significantly lower plasma viral RNA levels when compared with values obtained before initiation of treatment. There was a high frequency (4 of 11) of the protease L10F substitution in ZDV/3TC/IDV-treated patients that was associated with virological failure but did not result in phenotypic resistance to any of the PIs tested. Conclusions ZDV mutations were not detected in ZDV/3TC/PI-treated patients and they developed slowly in those treated with ZDV/3TC. Few protease mutations known to confer phenotypic PI resistance developed in the ZDV/3TC/PI arms of either study. The low prevalence of ZDV and PI mutations is encouraging regarding the future treatment options of these patients.

The second generation Hoechst-Bayer non-nucleoside inhibitor, HBY 097 ( S -4-isopropoxycarbonyl-6-methoxy-3-(methylthiomethyl)-3,4-dihydroqui noxalin-2(1 H )-thione), is an extremely potent inhibitor of HIV-1 reverse transcriptase (RT) and of HIV-1 infection in cell culture. HBY 097 selects for unusual drug-resistance mutations in HIV-1 RT (e.g. Gly190Glu) when compared with other non-nucleoside RT inhibitors (NNRTIs), such as nevirapine, α-APA and TIBO. We have determined the structure of HBY 097 complexed with wild-type HIV-1 RT at 3.1 A resolution. The HIV-1 RT/HBY 097 structure reveals an overall inhibitor geometry and binding mode differing significantly from RT/NNRTI structures reported earlier, in that HBY 097 does not adopt the usual butterfly-like shape. We have determined the structure of the Tyr188Leu HIV-1 RT drug-resistant mutant in complex with HBY 097 at 3.3 A resolution. HBY 097 binds to the mutant RT in a manner similar to that seen in the wild-type RT/HBY 097 complex, although there are some repositioning and conformational alterations of the inhibitor. Conformational changes of the structural elements forming the inhibitor-binding pocket, including the orientation of some side-chains, are observed. Reduction in the size of the 188 side-chain and repositioning of the Phe227 side-chain increases the volume of the binding cavity in the Tyr188Leu HIV-1 RT/HBY 097 complex. Loss of important protein-inhibitor interactions may account for the reduced potency of HBY 097 against the Tyr188Leu HIV-1 RT mutant. The loss of binding energy may be partially offset by additional contacts resulting from conformational changes of the inhibitor and nearby amino acid residues. This would suggest that inhibitor flexibility can help to minimize drug resistance.

An azidothymidine (AZT)-resistant virus strain (HIV-1/AZT) (containing the 67 Asp → Asn, 70 Lys → Arg, 215 Thr → Phe and 219 Lys → Gln mutations into its reverse transcriptase) was grown in the combined presence of 2′,3t - dideoxy-3′-thiacytidine (3TC, lamivudine) and the nonnucleoside reverse transcriptase inhibitor (S)-4-isopropoxycarbonyl-6-methoxy-3-(methylthiomethyl)-3,4-dihydroquinoxaline-2(1H)-thione (quinoxaline HBY 097). Replication of HIV-1/AZT was inhibited to a significantly greater extent by the combination of 3TC and quinoxaline HBY 097 than by either drug alone. Virus breakthrough was markedly delayed in the combined presence of 3TC and HBY 097 at drug concentrations as low as 0.05 μg/mL and 0.0025 μg/mL, respectively. The virus that was recovered after exposure to the compounds (3TC and HBY 097) individually had acquired, in the genetic AZT-resistance background of HIV-1/AZT, 103 Lys → Glu and 106 Val → Ala mutations. The 103 Lys → Glu mutation had not been observed before. However, both virus mutants retained marked sensitivity to HBY 097. In all cases, the genotypic AZT-resistance mutations were maintained in the mutant virus RT genomes, and the viruses also remained phenotypically resistant to AZT. Given the exquisite potency of a concomitant combination of 3TC and HBY 097 in suppressing virus replication, this drug combination should be further pursued in clinical trials in HIV-1-infected individuals.

In 1899Reichenow described an african bushshrike in juvenile plumage as a new species. He named itLaniarius dubiosus. DNA from type material (feathers and skin) was extracted and DNA sequences from the mitochondrial Cyt-b gene were analysed. Comparisons of DNA-sequences from other bushshrikes (including the type-specimen from Luehder's bushshrikeLaniarius luhderi) support the judgement that “dubiosus” does not represent a full species rather than a representative of the western subspecies of the Luehder's bushshrikeLaniarius luehderi.

DNA-Sequenzanalysen mitochondrialer Cytochrom-b-Abschnitte zeigen, das der vonReichenow 1899 neu beschriebene BuschwurgerLaniarius dubiosus aus Kamerun mit groser Wahrscheinlichkeit ein Jungvogel der westlichen Rasse des BraunscheitelwurgersLaniarius luhderi ist. Die Vermutung,L. dubiosus konne ein Jungvogel vonL. liberatus sein, konnte nicht bestatigt werden. Fur die Typusbeschreibung vonL. liberatus werden erganzende Daten zur Stimme (Sonagramme) und zur Gefiederfarbung vorgelegt, die die publizierte Beschreibung erganzen und z. T. korrigieren.

This Phase IIb study explored the antiviral activity and safety of the investigational CCR5 antagonist aplaviroc (APL) in antiretroviral-naive patients harbouring R5-tropic virus.One hundred and forty-seven patients were randomized 2:2:1 to one of two APL dosing regimens or efavirenz (EFV). All dosage arms were administered twice daily and in combination with lamivudine/zidovudine (3TC/ZDV; Combivir, COM). Efficacy, safety, and pharmacokinetic parameters were assessed.This study was prematurely terminated due to APL-associated idiosyncratic hepatotoxicity. The primary endpoint of the study was the proportion of patients with plasma HIV-1 RNA400 copies/ml who remained on randomized treatment through week 12. Of the 147 patients enrolled, 145 patients received one dose of treatment and were included in the intention-to-treat population. The proportion of patients with HIV-1 RNA400 copies/ml at week 12 was 53%, 50% and 66% in the APL 600 mg twice daily, APL 800 mg twice daily, and EFV arms, respectively. Common clinical adverse events (AEs) were diarrhoea, nausea, fatigue and headache. APL demonstrated non-linear pharmacokinetics with high interpatient variability. In addition to the hepatic findings, there was an apparent dose-response relationship in the incidence of diarrhoea.Whereas target plasma concentrations of APL were achieved, the antiviral activity of APL as the third agent in a triple drug regimen did not appear to be comparable to EFV in this treatment-naive patient population.

Antibodies directed against the glycoprotein C (gC) of herpes simplex virus type 1 (HSV-1) are known to be mainly HSV-1-specific, whereas antibodies against other major HSV-1 glycoproteins cross-react with HSV-2 antigens. To investigate the immunological features of gC-1, the gene encoding gC-1 was isolated and cloned from DNA of cells infected with HSV-1. The 3.6 kbp SalI fragment R of HSV-1 DNA was modified in order to place the gene under transcriptional control of the glucocorticoid dependent promoter of the MMTV-LTR. NIH 3T3 cells were transfected with the resulting plasmid. Cell lines established by selection for the vector-encoded marker gene were tested for the ability to synthesize gC-1 after addition of dexamethasone to the growth medium. Glycoprotein-enriched cell extracts of several clones were shown to contain gC-1 by immunoblotting using a gC-1-specific monoclonal antibody. One cell line was used to show the presence of gC-1 also in the culture supernatant. gC-1 synthesis decreased after several passages of the cells but could be restimulated by the addition of 5-azacytidine to the cultures.

In vitro resistance of HIV-1 against high levels of HBY 097 (( S )-4-isopropoxycarbonyl-6-methoxy-3-(methylthiomethyl)-3,4-dihydro-quinoxaline-2(1 H )-thione) and other quinoxaline nonnucleoside reverse transcriptase inhibitors (NNRTIs) is characterized by a specific amino acid substitution in the reverse transcriptase (RT), Gly190Glu. This change results in decreased RT polymerase activity and in reduced growth properties of the corresponding viral variant. Here we show that the appearance of the crippling mutation at codon 190 can be prevented by lowering the selective pressure exerted by HBY 097. Under low selective pressure an accumulation of other NNRTI-specific mutations is observed. Up to five NNRTI-specific substitutions were detected in some of these virus lineages. In addition, we report novel RT amino acid changes which were not observed previously, including Val106Ile, Val106Leu, and Gly190Thr. HBY 097 selects for different mutational patterns under high and low selective pressure conditions, respectively. Thus, the type of mutations which appear in HIV-infected patients undergoing therapy may be determined by the levels of the selecting drug.

to –1·38 log10) (table). In one of five patients who received 250 mg and two of five patients on 750 mg, viral load went below detection. In the high-dose cohorts, the mean viral load stayed below the value at entry after a 7-day washout period (–0·22 to –0·27 log10), in contrast with placebo treated patients, who had +0·25 and +0·58 log10 increase in viral load. In order to evaluate the generation of resistant viruses under short-term monotherapy, half maximum inhibition values by the drug in cell culture (IC50) were determined from viruses isolated from the patients before and after therapy. IC50 values at entry were between 0·1 and 3 nmoL, except for patient 6 in the 750 mg group, who had a resistant virus at entry with an IC50 of 160 nmoL, containing a NNRTI resistance mutation as well as a zidovudineresistance mutation in virions derived from plasma and in cultured virus. Development of a less sensitive virus after treatment was seen in only one patient in the 750 mg study and one patient in the 1000 mg study. No correlation was seen between initial viral load and the probability for development of a less sensitive virus (data not shown). The elevations in IC50 values were moderate (15 and 2·2 nmoL, respectively) and correlated with a partial or full mutation at position 103 of the reverse transcriptase. In studies with nevirapine, resistant virus replaced wild type within 2–4 weeks in all patients. These data suggest that HBY097 and related compounds are promising second-generation NNRTIs, which could be included in first-line combination therapies.