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1.
Kriengsak Limkittikul Pornthep Chanthavanich Kang Sung Lee Jung-Seok Lee Supawat Chatchen Sl-Ki Lim Watcharee Arunsodsai In-Kyu Yoon Jacqueline Kyungah Lim 《PLoS neglected tropical diseases》2022,16(1)
BackgroundTo determine the seroprevalence and transmission dynamics of dengue virus (DENV), age-stratified longitudinal serological surveys were conducted in Bangphae district, Ratchaburi province, Thailand, for 3 years between April 2012 and April 2015.MethodologyThe surveys enrolled 2012 healthy children and adults between 1 and 55 years-of-age, and a longitudinal serosurvey of six repeated bleeds of the same cohort of individuals was conducted every 8 months for the first 2 years (M0, M8, M16) and every half a year (M24, M30, M36) for the rest of the study period. All samples were tested using in-house indirect sandwich dengue IgG ELISA to determine DENV antibody titer, and 640 paired samples which showed rising of DENV IgG titers in paired serum were further tested using in-house neutralization assay, Plaque Reduction Neutralization Test (PRNT50).Principal findingsWhen compared against the gold standard based on the results of PRNT50, sensitivity and specificity of indirect ELISA were found to be both about 85%. The overall DENV IgG positivity determined by ELISA was 74.3% in 2012 and increased to 79.4% by the final sample collection in 2015. In our study sample, more than 98% of subjects older than 25 years were found to be seropositive. Among 518 IgG negative subjects at enrollment, the seroconversion rates were measured in paired bleeds; the rates (between successive visits, approximately 6 months) ranged between 4.8% (between M16 and M24) and 14.7% (between M0 and M8). The dominant serotype of primary DENV infection cases based on seroconversion was identified from the PRNT results and it was DENV-2.ConclusionsOur study documented high levels of seroprevalence and rate of transmission. Given the importance of the serostatus and disease burden in consideration for dengue vaccine introduction, our data could be used in decision-making on implementation of various dengue control and preventive measures. 相似文献
2.
Somchart Maenpuen Watcharee Amornwatcharapong Pasupat Krasatong Jeerus Sucharitakul Bruce A. Palfey Yongyuth Yuthavong Penchit Chitnumsub Ubolsree Leartsakulpanich Pimchai Chaiyen 《The Journal of biological chemistry》2015,290(13):8656-8665
Serine hydroxymethyltransferase (SHMT) is a pyridoxal 5′-phosphate (PLP)-dependent enzyme that catalyzes a hydroxymethyl group transfer from l-serine to tetrahydrofolate (H4folate) to yield glycine and 5,10-methylenetetrahydrofolate (CH2-H4folate). SHMT is crucial for deoxythymidylate biosynthesis and a target for antimalarial drug development. Our previous studies indicate that PvSHMT catalyzes the reaction via a ternary complex mechanism. To define the kinetic mechanism of this catalysis, we explored the PvSHMT reaction by employing various methodologies including ligand binding, transient, and steady-state kinetics as well as product analysis by rapid-quench and HPLC/MS techniques. The results indicate that PvSHMT can bind first to either l-serine or H4folate. The dissociation constants for the enzyme·l-serine and enzyme·H4folate complexes were determined as 0.18 ± 0.08 and 0.35 ± 0.06 mm, respectively. The amounts of glycine formed after single turnovers of different preformed binary complexes were similar, indicating that the reaction proceeds via a random-order binding mechanism. In addition, the rate constant of glycine formation measured by rapid-quench and HPLC/MS analysis is similar to the kcat value (1.09 ± 0.05 s−1) obtained from the steady-state kinetics, indicating that glycine formation is the rate-limiting step of SHMT catalysis. This information will serve as a basis for future investigation on species-specific inhibition of SHMT for antimalarial drug development. 相似文献
3.
Saisongkorh W El Karkouri K Patrice JY Bernard A Rolain JM Raoult D 《FEMS immunology and medical microbiology》2012,64(1):111-114
In cell culture, Rickettsia felis grows only at low temperatures (< 31 °C). Therefore, its ability to enter, survive and grow in cell lines has primarily been tested in cells derived from amphibians and arthropods, which naturally grow at low temperatures, and only infrequently in mammalian cells. We subcultured R. felis in mammalian cells for more than 10 passages using media supplemented with tryptose phosphate broth (TPB) and found that TPB is critical for optimal growth of R. felis in mammalian cells. 相似文献
4.
Sirivichayakul C Limkittikul K Chanthavanich P Jiwariyavej V Chokejindachai W Pengsaa K Suvannadabba S Dulyachai W Letson GW Sabchareon A 《PLoS neglected tropical diseases》2012,6(2):e1520
Background
Dengue infection is one of the most important mosquito-borne diseases. More data regarding the disease burden and the prevalence of each clinical spectrum among symptomatic infections and the clinical manifestations are needed. This study aims to describe the incidence and clinical manifestations of symptomatic dengue infection in Thai children during 2006 through 2008.Study Design
This study is a school-based prospective open cohort study with a 9,448 person-year follow-up in children aged 3–14 years. Active surveillance for febrile illnesses was done in the studied subjects. Subjects who had febrile illness were asked to visit the study hospital for clinical and laboratory evaluation, treatment, and serological tests for dengue infection. The clinical data from medical records, diary cards, and data collection forms were collected and analyzed.Results
Dengue infections were the causes of 12.1% of febrile illnesses attending the hospital, including undifferentiated fever (UF) (49.8%), dengue fever (DF) (39.3%) and dengue hemorrhagic fever (DHF) (10.9%). Headache, anorexia, nausea/vomiting and myalgia were common symptoms occurring in more than half of the patients. The more severe dengue spectrum (i.e., DHF) had higher temperature, higher prevalence of nausea/vomiting, abdominal pain, rash, diarrhea, petechiae, hepatomegaly and lower platelet count. DHF cases also had significantly higher prevalence of anorexia, nausea/vomiting and abdominal pain during day 3–6 and diarrhea during day 4–6 of illness. The absence of nausea/vomiting, abdominal pain, diarrhea, petechiae, hepatomegaly and positive tourniquet test may predict non-DHF.Conclusion
Among symptomatic dengue infection, UF is most common followed by DF and DHF. Some clinical manifestations may be useful to predict the more severe disease (i.e., DHF). This study presents additional information in the clinical spectra of symptomatic dengue infection. 相似文献5.
Case-Control Approach to Identify Plasmodium falciparum Polymorphisms Associated with Severe Malaria
Background
Studies to identify phenotypically-associated polymorphisms in the Plasmodium falciparum 23 Mb genome will require a dense array of marker loci. It was considered promising to undertake initial allelic association studies to prospect for virulence polymorphisms in Thailand, as the low endemicity would allow higher levels of linkage disequilibrium (LD) than would exist in more highly endemic areas.Methodology/Principal Findings
Assessment of LD was first made with 11 microsatellite loci widely dispersed in the parasite genome, and 16 microsatellite loci covering a ∼140 kb region of chromosome 2 (an arbitrarily representative non-telomeric part of the genome), in a sample of 100 P. falciparum isolates. The dispersed loci showed minimal LD (Index of Association, ISA = 0.013, P = 0.10), while those on chromosome 2 showed significant LD values mostly between loci <5 kb apart. A disease association study was then performed comparing parasites in 113 severe malaria cases and 245 mild malaria controls. Genotyping was performed on almost all polymorphisms in the binding domains of three erythrocyte binding antigens (eba175, eba140 and eba181), and repeat sequence polymorphisms ∼2 kb apart in each of three reticulocyte binding homologues (Rh1, Rh2a/b, and Rh4). Differences between cases and controls were seen for (i) codons 388-90 in eba175, and (ii) a repeat sequence centred on Rh1 codon 667.Conclusions/Significance
Allelic association studies on P. falciparum require dense genotypic markers, even in a population of only moderate endemicity that has more extensive LD than highly endemic populations. Disease-associated polymorphisms in the eba175 and Rh1 genes encode differences in the middle of previously characterised erythrocyte binding domains, marking these for further investigation. 相似文献6.
The Plasmodium falciparum apical membrane antigen 1 (AMA1) is a leading candidate for a malaria vaccine. Here, within-population analyses of alleles from 50 Thai P. falciparum isolates yield significant evidence for balancing selection on polymorphisms within the disulfide-bonded domains I and III of the surface accessible ectodomain of AMA1, a result very similar to that seen previously in a Nigerian population. Studying the frequency of nucleotide polymorphisms in both populations shows that the between-population component of variance (F(ST)) is significantly lower in domains I and III compared to the intervening domain II and compared to 11 unlinked microsatellite loci. A nucleotide site-by-site analysis shows that sites with exceptionally high or low F(ST) values cluster significantly into serial runs, with four runs of low values in domain I and one in domain III. These runs may map the sequences that are consistently under the strongest balancing selection from naturally acquired immune responses. 相似文献
7.
Sopita Ruangcharoen Waraporn Suwannarong Marie Rossini Carmela T. Lachica Jan G. M. Bolscher Kamran Nazmi Watcharee Khunkitti Suwimol Taweechaisupapong 《World journal of microbiology & biotechnology》2017,33(9):167
Lactoferrin chimera (LFchimera), a heterodimeric peptide containing lactoferrampin (LFampin265–284) and a part of lactoferricin (LFcin17–30), possesses a broad spectrum of antimicrobial activity. However, there is no report on the inhibitory effects of LFchimera against multispecies oral biofilms. This study aimed to determine the effects of LFchimera in comparison to chlorhexidine digluconate (CHX) and minocycline hydrochloride (MH), on in vitro multispecies biofilms derived from subgingival plaque of periodontitis patients harboring Aggregatibacter actinomycetemcomitans. First the effects of LFchimera against planktonic and an 1-day old biofilm of the periodontopathic bacteria, A. actinomycetemcomitans ATCC 43718 were established. Then, the effects on biofilm formation and bacterial viability in the multispecies biofilm were determined by crystal violet staining and LIVE/DEAD BacLight Bacterial Viability kit, respectively. The results revealed that a significant reduction (P?<?0.05) in biofilm formation occurred after 15 min exposure to 20 µM of LFchimera or CHX compared to control. In contrast, MH at concentration up to 100 µM did not inhibit biofilm formation. The ratio of live/dead bacteria in biofilm was also significantly lower after 15 min exposure to 20 µM of LFchimera compared to control and 20–50 µM of CHX and MH. Altogether, the results obtained indicate that LFchimera is able to inhibit in vitro subgingival biofilm formation and reduce viability of multispecies bacteria in biofilm better than CHX and MH. 相似文献
8.
Reiling L Richards JS Fowkes FJ Barry AE Triglia T Chokejindachai W Michon P Tavul L Siba PM Cowman AF Mueller I Beeson JG 《Journal of immunology (Baltimore, Md. : 1950)》2010,185(10):6157-6167
Abs targeting blood-stage Ags of Plasmodium falciparum are important in acquired immunity to malaria, but major targets remain unclear. The P. falciparum reticulocyte-binding homologs (PfRh) are key ligands used by merozoites during invasion of erythrocytes. PfRh2a and PfRh2b are functionally important members of this family and may be targets of protective immunity, but their potential role in human immunity has not been examined. We expressed eight recombinant proteins covering the entire PfRh2 common region, as well as PfRh2a- and PfRh2b-specific regions. Abs were measured among a cohort of 206 Papua New Guinean children who were followed prospectively for 6 mo for reinfection and malaria. At baseline, Abs were associated with increasing age and active infection. High levels of IgG to all PfRh2 protein constructs were strongly associated with protection from symptomatic malaria and high-density parasitemia. The predominant IgG subclasses were IgG1 and IgG3, with little IgG2 and IgG4 detected. To further understand the significance of PfRh2 as an immune target, we analyzed PfRh2 sequences and found that polymorphisms are concentrated in an N-terminal region of the protein and seem to be under diversifying selection, suggesting immune pressure. Cluster analysis arranged the sequences into two main groups, suggesting that many of the haplotypes identified may be antigenically similar. These findings provide evidence suggesting that PfRh2 is an important target of protective immunity in humans and that Abs act by controlling blood-stage parasitemia and support its potential for vaccine development. 相似文献
9.
Watcharee Saisongkorh Catherine Robert Bernard La Scola Didier Raoult Jean-Marc Rolain 《PloS one》2010,5(9)
Background
Bartonella species cospeciate with mammals and live within erythrocytes. Even in these specific niches, it has been recently suggested by bioinformatic analysis of full genome sequences that Lateral Gene Transfer (LGT) may occur but this has never been demonstrated biologically. Here we describe the sequence of the B. rattaustraliani (AUST/NH4T) circular plasmid (pNH4) that encodes the tra cluster of the Type IV secretion system (T4SS) and we eventually provide evidence that Bartonella species may conjugate and exchange this plasmid inside amoeba.Principal Findings
The T4SS of pNH4 is critical for intracellular viability of bacterial pathogens, exhibits bioinformatic evidence of LGT among bacteria living in phagocytic protists. For instance, 3 out of 4 T4SS encoding genes from pNH4 appear to be closely related to Rhizobiales, suggesting that gene exchange occurs between intracellular bacteria from mammals (bartonellae) and plants (Rhizobiales). We show that B. rattaustraliani and Rhizobium radiobacter both survived within the amoeba Acanthamoeba polyphaga and can conjugate together. Our findings further support the hypothesis that tra genes might also move into and out of bacterial communities by conjugation, which might be the primary means of genomic evolution for intracellular adaptation by cross-talk of interchangeable genes between Bartonella species and plant pathogens.Conclusions
Based on this, we speculate that amoeba favor the transfer of genes as phagocytic protists, which allows for intraphagocytic survival and, as a consequence, promotes the creation of potential pathogenic organisms. 相似文献10.
Linda Reiling Jack S. Richards Freya J. I. Fowkes Danny W. Wilson Watcharee Chokejindachai Alyssa E. Barry Wai-Hong Tham Janine Stubbs Christine Langer John Donelson Pascal Michon Livingstone Tavul Brendan S. Crabb Peter M. Siba Alan F. Cowman Ivo Mueller James G. Beeson 《PloS one》2012,7(9)