HIV-1 subtype B and CRF01_AE have been in circulation in Thailand and Southeast Asia for more than a decade. Initially separated by risk group, the two strains are increasingly intermixed, and two recombinant strains of essentially reciprocal structure have been recently reported. Here we identify additional CRF_01B recombinants and provide the evidence that HIV-1 strains now pass freely between the two high-risk populations. HIV isolates that showed discordance between CRF01_AE and subtype B in multi-region genotyping assays were selected for the study. They were drawn from 3 different cohorts in Thailand representing different risk behaviors and demographic characteristics: a drug user cohort in the north, a family planning clinic attendee cohort in the southeast, and a cohort study of the mucosal virology and immunology of HIV-1 infection in Thailand. The DNA from these isolates was PCR amplified to recover the full HIV-1 genome and subjected to sequencing and phylogenetic analysis. We establish that one particular CRF_01B recombinant, with the external envelope of subtype B and the rest of the genome from CRF01_AE, is circulating widely in Thailand. Termed CRF15_01B (also referred to as CRF15), the strain was primarily heterosexually transmitted, although injecting drug use (IDU) also played a role. In aggregate data from the studies, CRF15 constituted 1.7% of all HIV-1 infections (95% confidence interval 0.5-4.4%) and was dispersed widely in the country. The previously separate heterosexual and IDU epidemics have apparently been bridged by a new CRF. The entry of CRF15 into the mainstream of the epidemic signals new complexity in the long stable molecular picture in Thailand. These recombinants must be considered in ongoing or projected efficacy evaluations of HIV-1 vaccines and antiviral therapies.

Abstract. The single-dose pharmacokinetics of 100 mg of orally administered artesunate (AS) were studied in 6 patient volunteers with uncomplicated falciparum malaria and in 6 healthy volunteers. Plasma concentrations of both the parent drug, AS, and its major metabolite, dihydroartemisinin (DHA), were measured simultaneously by highperformance liquid chromatography (HPLC) with electrochemical detection (ECD). The antimalarial activity of each plasma sample measured by an in vitro bioassay (BA) was used to derive activity concentrations. Artesunate was absorbed rapidly and then almost completely hydrolyzed to DHA in patients, whereas hydrolysis was incomplete in healthy volunteers. The mean Ϯ standard deviation (SD) maximum concentration (C max ) of AS was 296 Ϯ 110 nmol/ L, the time to peak blood level (t max ) was 0.71 Ϯ 0.66 hr, the half-life (t 1/2,z ) was 0.41 Ϯ 0.34 hr, and the bioavailability over 12 hr (area under the curve [AUC] (0-12) ) was 253 Ϯ 185 nmol hr/L. Measured by HPLC, the C max and AUC (0)(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) values of DHA in patients with malaria were significantly greater than in volunteers (1,948 Ϯ 772 and 1,192 Ϯ 315 nmol/L; 4,024 Ϯ 1,585 and 1,763 Ϯ 607 nmol hr/L, respectively; P Յ 0.05). These differences were even greater when measured by BA. The C max for patients with malaria was 2,894 Ϯ 2,497 and 795 Ϯ 455 nmol/L for volunteers, and AUC (0-12) was 5,970 Ϯ 3,625 and 1,307 Ϯ 391 nmol hr/L, respectively (P Յ 0.05). In contrast, DHA parameter estimates for t 1/2,z and t max were similar between patients and healthy volunteers, with values of 0.80 Ϯ 0.30 versus 0.87 Ϯ 0.06 hr and 1.50 Ϯ 0.55 versus 1.13 Ϯ 0.52 hr, respectively (P Ͼ 0.5). Both drug metabolism and tissue protein binding could contribute to the differences between the antimalarial activity of artemisinin drugs in healthy volunteers and malaria infected patients.

No abstract

BackgroundThe recent dramatic decline in dihydroartemisinin-piperaquine (DHA-PPQ) efficacy in northwestern Cambodia has raised concerns about the rapid spread of piperaquine resistance just as DHA-PPQ is being introduced as first-line therapy in neighbouring countries.MethodsEx vivo parasite susceptibilities were tracked to determine the rate of progression of DHA, PPQ and mefloquine (MQ) resistance from sentinel sites on the Thai–Cambodian and Thai–Myanmar borders from 2010 to 2015. Immediate ex vivo (IEV) histidine-rich protein 2 (HRP-2) assays were used on fresh patient Plasmodium falciparum isolates to determine drug susceptibility profiles.ResultsIEV HRP-2 assays detected the precipitous emergence of PPQ resistance in Cambodia beginning in 2013 when 40 % of isolates had an IC90 greater than the upper limit of prior years, and this rate doubled to 80 % by 2015. In contrast, Thai–Myanmar isolates from 2013 to 14 remained PPQ-sensitive, while northeastern Thai isolates appeared to have an intermediate resistance profile. The opposite trend was observed for MQ where Cambodian isolates appeared to have a modest increase in overall sensitivity during the same period, with IC50 declining to median levels comparable to those found in Thailand. A significant association between increased PPQ IC50 and IC90 among Cambodian isolates with DHA-PPQ treatment failure was observed. Nearly all Cambodian and Thai isolates were deemed artemisinin resistant with a >1 % survival rate for DHA in the ring-stage assay (RSA), though there was no correlation among isolates to indicate cross-resistance between PPQ and artemisinins.ConclusionsClinical DHA-PPQ failures appear to be associated with declines in the long-acting partner drug PPQ, though sensitivity appears to remain largely intact for now in western Thailand. Rapid progression of PPQ resistance associated with DHA-PPQ treatment failures in northern Cambodia limits drugs of choice in this region, and urgently requires alternative therapy. The temporary re-introduction of artesunate AS-MQ is the current response to PPQ resistance in this area, due to inverse MQ and PPQ resistance patterns. This will require careful monitoring for re-emergence of MQ resistance, and possible simultaneous resistance to all three drugs (AS, MQ and PPQ).Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-016-1569-y) contains supplementary material, which is available to authorized users.

The natural history and progression of HIV-1 infection in Thailand and other developing countries in Asia and Africa have not been well defined. Nevertheless, valid data are needed to evaluate the effects of interventions, which are designed to delay progression. We evaluated the progression to AIDS and death in 235 men who seroconverted during their 2 years of service in the Royal Thai Army. The men were conscripted at age 21 and seroconverted within a 6-month window during follow-up while in the military. The seroconverters were matched with men who were seronegative when discharged. Of the HIV-positive men, 156 (66.4%) were alive, 77 (32.8%) had died, and 2 (0.8%) could not be located 5-7 years after their seroconversion and discharge from the military. The 5-year survival rate was 82.3%; the median times to clinical AIDS and a CD4 cell count of <200/microL was 7.4 years and 6.9 years, respectively. The mortality rate was 56.3 deaths per 1000 patient-years for HIV-positive men and 6.1 deaths per 1000 patient-years for HIV-negative men. Our data suggest a more rapid progression to AIDS and death after HIV-1 infection in young men in Thailand than has been reported for similarly aged cohorts in developed countries.