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Phnom Penh, Cambodia

Kond S.,Thammasat University | Sattaponpa C.,Thammasat University | Phongpaichi S.,Prince of Songkla University | Srija A.,USAMC AFRIMS | Ithara A.,Thammasat University
Journal of the Medical Association of Thailand

Background: Bacterial infections caused by resistant strains have been increased dramatically. Pikutbenjakul, a Thai medicinal plant formula containing Piper longum, Piper sarmentosum, Piper interruptum, Plumbago indica and Zingiber officinale have been widely used in Thai traditional medicine. Objective: To determine antimicrobial activity of Pikutbenjakul formula and its components in order to develop the medicinal plants for alternative treatment of bacteria causing diarrhea. Material and Method: Activity of Pikutbenjakul formula and its components was tested using disc diffusion and broth dilution methods against bacteria associated a set of bacteria associated with diarrheal disease including Vibrio cholerae, Vibrio vulnificus, Salmonella, Shigella, Escherichia coli (EIEC, ETEC, EPEC, EAEC and EHEC) and Staphylococcus aureus. The extraction was performed by maceration in 95% ethanol. Results: The results showed all tested strains were susceptible to P. indica while other components were able to inhibit some strains. P. sarmentosum showed antimicrobial activity against Vibrios with the MIC values between 0.625 to ≥ 5mg/ml. P. sarmentosum, P. indica and Pikutbenjakul formulas inhibited the growth of all Vibrios. P. interruptum inhibited V. cholerae serogroups O1 and non-O1/non-O139. P. longum was able to inhibit only two isolates of V. cholerae serogroup O139 (MIC = 1.25 mg/ml) and V. vulnificus (MIC ≥ 5 mg/ml). The activity of Pikutbenjakul containing Zingiber spp. and Pikutbenjakul containing Z. officinal against Vibrios, Shigella spp. and S. aureus was not significantly different. P. indica could inhibit Salmonella (MIC ≥ 5 mg/ml), E. coli (MIC ≥ 5 mg/ml) and S. aureus (MIC = 1.25 mg/ml). Conclusion: The results support the Thai medicinal plants for treatment of diarrhea caused by these bacteria. This study also provides an insightful knowledge on antimicrobial activity which would lead to further development of an effective formula of Pikutbenjakul for diarrheal disease and other infectious diseases in future. Source

Harrington L.C.,Cornell University | Fleisher A.,University of California at Davis | Ruiz-Moreno D.,Cornell University | Ruiz-Moreno D.,University of Buenos Aires | And 10 more authors.
PLoS Neglected Tropical Diseases

Background: Mosquito biting frequency and how bites are distributed among different people can have significant epidemiologic effects. An improved understanding of mosquito vector-human interactions would refine knowledge of the entomological processes supporting pathogen transmission and could reveal targets for minimizing risk and breaking pathogen transmission cycles. Methodology and principal findings: We used human DNA blood meal profiling of the dengue virus (DENV) vector, Aedes aegypti, to quantify its contact with human hosts and to infer epidemiologic implications of its blood feeding behavior. We determined the number of different people bitten, biting frequency by host age, size, mosquito age, and the number of times each person was bitten. Of 3,677 engorged mosquitoes collected and 1,186 complete DNA profiles, only 420 meals matched people from the study area, indicating that Ae. aegypti feed on people moving transiently through communities to conduct daily business. 10–13% of engorged mosquitoes fed on more than one person. No biting rate differences were detected between high- and low-dengue transmission seasons. We estimate that 43–46% of engorged mosquitoes bit more than one person within each gonotrophic cycle. Most multiple meals were from residents of the mosquito collection house or neighbors. People ≤25 years old were bitten less often than older people. Some hosts were fed on frequently, with three hosts bitten nine times. Interaction networks for mosquitoes and humans revealed biologically significant blood feeding hotspots, including community marketplaces. Conclusion and significance: High multiple-feeding rates and feeding on community visitors are likely important features in the efficient transmission and rapid spread of DENV. These results help explain why reducing vector populations alone is difficult for dengue prevention and support the argument for additional studies of mosquito feeding behavior, which when integrated with a greater understanding of human behavior will refine estimates of risk and strategies for dengue control. © 2014, Public Library of Science. All rights reserved. Source

Iyori M.,Kanazawa University | Nakaya H.,Kanazawa University | Inagaki K.,Otsuka Pharmaceutical Factory Inc. | Pichyangkul S.,USAMC AFRIMS | And 8 more authors.

We have previously developed a new malaria vaccine delivery system based on the baculovirus dual expression system (BDES). In this system, expression of malaria antigens is driven by a dual promoter consisting of the baculovirus-derived polyhedrin and mammal-derived cytomegalovirus promoters. To test this system for its potential as a vaccine against human malaria parasites, we investigated immune responses against the newly developed BDES-based Plasmodium falciparum circumsporozoite protein vaccines (BDES-PfCSP) in mice and Rhesus monkeys. Immunization of mice with BDES-PfCSP induced Th1/Th2-mixed type immune responses with high PfCSP-specific antibody (Ab) titers, and provided significant protection against challenge from the bites of mosquitoes infected with a transgenic P. berghei line expressing PfCSP. Next, we evaluated the immunogenicity of the BDES-PfCSP vaccine in a rhesus monkey model. Immunization of BDES-PfCSP elicited high levels of anti-PfCSP Ab responses in individual monkeys. Moreover, the sera from the immunized monkeys remarkably blocked sporozoite invasion of HepG2 cells. Taken together with two animal models, our results indicate that this novel vaccine platform (BDES) has potential clinical application as a vaccine against malaria. © 2013 Iyori et al. Source

Sanchez A.M.,Duke University | Rountree W.,Duke University | Berrong M.,Duke University | Garcia A.,Duke University | And 8 more authors.
Journal of Immunological Methods

The interferon-gamma enzyme-linked immunospot (IFN-γ ELISpot) assay has been developed and used as an end-point assay in clinical trials for infectious diseases and cancer to detect the magnitude of antigen-specific immune responses. The ability to compare data generated by different laboratories across organizations is pivotal to understand the relative potency of different therapeutic and vaccine strategies. We developed an external proficiency program for the IFN-γ ELISpot assay that evaluates laboratory performance based on five parameters: timeliness for data reporting; ability to handle cellular samples; detection of background (non-specific) responses; accuracy to consensus of the results; and precision of the measurements. Points are awarded for each criterion, and the sum of the points is used to determine a numeric and adjectival performance rating. Importantly, the evaluation of the accuracy to the consensus mean for the detection of antigen-specific responses using laboratory-specific procedures informs each laboratory and its sponsor on the degree of concordance of its results with those obtained by other laboratories. This study will ultimately provide the scientific community with information on how to organize and implement an external proficiency program to evaluate longitudinally the performance of the participating laboratories and, therefore, fulfill the requirements of the GCLP guidelines for laboratories performing end-point IFN-γ ELISpot assay for clinical trials. © 2014 Elsevier B.V. Source

Miotto O.,University of Oxford | Miotto O.,Mahidol University | Miotto O.,Wellcome Trust Sanger Institute | Almagro-Garcia J.,University of Oxford | And 75 more authors.
Nature Genetics

We describe an analysis of genome variation in 825 P. falciparum samples from Asia and Africa that identifies an unusual pattern of parasite population structure at the epicenter of artemisinin resistance in western Cambodia. Within this relatively small geographic area, we have discovered several distinct but apparently sympatric parasite subpopulations with extremely high levels of genetic differentiation. Of particular interest are three subpopulations, all associated with clinical resistance to artemisinin, which have skewed allele frequency spectra and high levels of haplotype homozygosity, indicative of founder effects and recent population expansion. We provide a catalog of SNPs that show high levels of differentiation in the artemisinin-resistant subpopulations, including codon variants in transporter proteins and DNA mismatch repair proteins. These data provide a population-level genetic framework for investigating the biological origins of artemisinin resistance and for defining molecular markers to assist in its elimination. © 2013 Nature America, Inc. All rights reserved. Source

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