Publications by authors named "Wachareeporn Trinachartvanit"

25 Publications

  • Page 1 of 1

Reinstatement of Dermacentor tricuspis (Schulze, 1933) n. comb., n. stat. (Acari: Ixodidae) as a valid species, synonymization of D. atrosignatus Neumann, 1906 and description of a new species from Indonesia, Malaysia and Thailand.

Syst Parasitol 2021 Jun 23;98(3):207-230. Epub 2021 Apr 23.

Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand.

Re-examination of the holotype of Dermacentor atrosignatus Neumann, 1906 (Acari: Ixodidae) stored in the Natural History Museum (London, UK) revealed that this taxon is identical with D. auratus Supino, 1897 and should be treated as a junior synonym of the latter species. A correct name for the distinct species previously identified as D. atrosignatus Neumann, 1906 sensu Wassef & Hoogstraal, 1984 should be D. tricuspis (Schulze, 1933) n. comb., n. stat. Adults of D. tricuspis are redescribed here. Re-examination of extensive holdings of Oriental Dermacentor Koch, 1844 ticks stored in the United States National Tick Collection revealed that a morphologically distinct new species of this genus, namely D. falsosteini D. Apanaskevich, M. Apanaskevich & Nooma n. sp. should be recognized. Adults of D. tricuspis and D. falsosteini n. sp. can be distinguished from other species of Oriental Dermacentor and each other by the colour pattern of the conscutum and scutum, the pattern of punctations on the pseudoscutum and scutum, the shape of female genital structures and spurs on coxa I. Dermacentor tricuspis is recorded from Indonesia, Malaysia, the Philippines and Thailand where the adults were mostly collected from various species of wild pigs (Artiodactyla: Suidae) and vegetation; few adults were available from other mammals (Artiodactyla: Bovidae; Carnivora: Canidae, Felidae, Ursidae; Pholidota: Manidae), as well as humans and reptiles (Squamata: Elapidae, Varanidae). One male was reared from a nymph collected on a rodent (Rodentia: Muridae). Dermacentor falsosteini n. sp. is found in Indonesia, Malaysia and Thailand where the adults were collected from bearded pig, Sus barbatus Müller, wild boar, S. scrofa Linnaeus, unidentified wild pig, Sus sp. (Artiodactyla: Suidae), Malayan tapir, Tapirus indicus Desmarest (Perissodactyla: Tapiridae), human and vegetation.
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http://dx.doi.org/10.1007/s11230-021-09972-6DOI Listing
June 2021

Partial DnaK protein expression from Coxiella-like endosymbiont of Rhipicephalus annulatus tick.

PLoS One 2021 1;16(4):e0249354. Epub 2021 Apr 1.

Department of Biology, Biodiversity Research Cluster, Faculty of Science, Mahidol University, Bangkok, Thailand.

Q fever is one of the most important zoonotic diseases caused by the obligate intracellular bacteria, Coxiella burnetii. This bacterial infection has been frequently reported in both humans and animals, especially ruminants. Ticks are important ectoparasite and serve as reservoir hosts of Coxiella-like endosymbionts (CLEs). In this study, we have attempted to express chaperone-coding genes from CLEs of Rhipicephalus annulatus ticks collected fromcow path. The partial DnaK coding sequence has been amplified and expressed by Escherichia coli. Amino acid sequences have been analyzed by MS-MS spectrometry and the UniProt database. Despites nucleotide sequences indicating high nucleotide variation and diversity, many nucleotide substitutions are synonymous. In addition, amino acid substitutions compensate for the physicochemical properties of the original amino acids. Immune Epitope Database and Analysis Resource (IEDB-AR) was employed to indicate the antigenicity of the partial DnaK protein and predict the epitopes of B-and T-cells. Interestingly, some predicted HLA-A and B alleles of the MHC-I and HLA-DR alleles belonging to MHC-II were similar to T-cell responses to C. burnetii in Q fever patients. Therefore, the partial DnaK protein of CLE from R. annulatus could be considered a vaccine candidate and immunogenic marker with future prospects.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0249354PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8016282PMC
April 2021

Roles of RcsA, an AhpD Family Protein, in Reactive Chlorine Stress Resistance and Virulence in Pseudomonas aeruginosa.

Appl Environ Microbiol 2020 10 1;86(20). Epub 2020 Oct 1.

Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok, Thailand

Reactive chlorine species (RCS), particularly hypochlorous acid (HOCl), are powerful antimicrobial oxidants generated by biological pathways and chemical syntheses. is an important opportunistic pathogen that has adapted mechanisms for protection and survival in harsh environments, including RCS exposure. Based on previous transcriptomic studies of HOCl exposure in , we found that the expression of , or , which encodes an alkyl hydroperoxidase D-like protein, exhibited the highest induction among the RCS-induced genes. In this study, expression was dominant under HOCl stress and greatly increased under HOCl-related stress conditions. Functional analysis of RcsA showed that the distinguishing core amino acid residues Cys60, Cys63, and His67 were required for the degradation of sodium hypochlorite (NaOCl), suggesting an extended motif in the AhpD family. After allelic exchange mutagenesis in the , the deletion mutant showed significantly decreased HOCl resistance. Ectopic expression of led to significantly increased NaOCl resistance in Moreover, the pathogenicity of the mutant decreased dramatically in both and host model systems compared to the wild type (WT). Finally, the Cys60, Cys63, and His67 variants of RcsA were unsuccessful at complementing phenotypes of the mutant. Overall, our data indicate the importance of RcsA in defense against HOCl stress under disinfections and during infections of hosts, which involves the catalytic Cys60, Cys63, and His67 residues. is a common pathogen that is a major cause of serious infections in many hosts. Hypochlorous acid (HOCl) is a potent antimicrobial agent found in household bleach and is a widely used disinfectant. has evolved adaptive mechanisms for protection and survival during HOCl exposure. We identified as a HOCl-responsive gene encoding an antioxidant protein that may be involved in HOCl degradation. RcsA has a distinguishing core motif containing functional Cys60, Cys63, and His67 residues. plays an important role in bleach tolerance, with expression of in also conferring HOCl resistance. Interestingly, RcsA is required for full virulence in worm and fruit fly infection models, indicating a correlation between mechanisms of bleach toxicity and host immunity during infection. This provides new insights into the mechanisms used by to persist in harsh environments such as hospitals.
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http://dx.doi.org/10.1128/AEM.01480-20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7531977PMC
October 2020

Description of a new species of Dermacentor Koch, 1844 (Acari: Ixodidae) from the mountains of Laos and Thailand.

Syst Parasitol 2020 08 3;97(4):347-355. Epub 2020 Jun 3.

Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand.

Dermacentor pasteuri n. sp. (Acari: Ixodidae) is described based on adults ex wild boar and vegetation from Laos and Thailand. Adults of D. pasteuri n. sp. are similar to those of D. compactus Neumann, 1901, but can be distinguished by the shape of conscutum in the male, development of dorsal cornua in the female, size and shape of spurs on coxae and coloration of leg segments in both sexes.
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http://dx.doi.org/10.1007/s11230-020-09916-6DOI Listing
August 2020

Reptile-associated Borrelia spp. In Amblyomma ticks, Thailand.

Ticks Tick Borne Dis 2020 01 14;11(1):101315. Epub 2019 Oct 14.

Biodiversity Research Cluster, Department of Biology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok, Thailand; Center of Excellence for Vectors and Vector-Borne Diseases, Faculty of Science, Mahidol University at Salaya, Phutthamonthon 4 Road, Nakhon Pathom, Thailand. Electronic address:

A total of 127 Amblyomma ticks (A. helvolum, A. varanense and A. geoemydae) were collected from reptiles: water monitors (Varanus salvator), Bengal monitors (Varanus bengalensis), Burmese pythons (Python bivittatus), yellow-spotted keelbacks (Xenochrophis flavipunctatus), keeled rat snakes (Ptyas carinata) and elongated tortoises (Indotestudo elongata) from nine provinces in Thailand. The presence of Borrelia spp. of the 16S rRNA, flaB, glpQ, groEL and gyrB genes was examined by conventional, semi-nested and nested PCR. Phylogenetic analyses using maximum likelihood method of housekeeping genes showed that most sequences of Borrelia spp. in these Amblyomma ticks belonged to the clade of reptile-associated (REP) borreliae. Interestingly, one Borrelia sp. in an A. geoemydae tick collected from an elongated tortoise clustered in the same clade as a Borrelia sp. detected from an A. geoemydae-infested turtle in Japan (it may belong to the same species given the identical sequences of their 16S rRNA, flaB and glpQ genes) and formed the same group with tick-borne relapsing fever (RF) borreliae of B. miyamotoi and B. theileri. Our findings are the first report on the presence of Borrelia spp. in A. helvolum and A. geoemydae ticks from reptiles in Thailand adding to the geographic distribution of Borrelia spp. in Asia.
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http://dx.doi.org/10.1016/j.ttbdis.2019.101315DOI Listing
January 2020

Description of a new species of Dermacentor Koch, 1844 (Acari: Ixodidae) from Laos and Thailand.

Syst Parasitol 2019 07 20;96(6):475-484. Epub 2019 May 20.

Department of Biology, Faculty of Science, Mahidol University, Bangkok, Thailand.

Dermacentor laothaiensis n. sp. (Acari: Ixodidae) is described based on adults ex wild boar and vegetation from Laos and Thailand. Adults of D. laothaiensis n. sp. are similar to those of D. bellulus (Schulze, 1935) and D. steini (Schulze, 1933) but can be distinguished by the conscutum shape, colour pattern of the conscutum and scutum, the density of punctations on the pseudoscutum and scutum and the shape of female genital structures.
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http://dx.doi.org/10.1007/s11230-019-09861-zDOI Listing
July 2019

Coxiella-like bacteria in fowl ticks from Thailand.

Parasit Vectors 2018 Dec 27;11(1):670. Epub 2018 Dec 27.

Biodiversity Research Cluster, Department of Biology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok, 10400, Thailand.

Background: Coxiella bacteria were identified from various tick species across the world. Q fever is a zoonotic disease caused by the bacteria Coxiella burnetii that most commonly infects a variety of mammals. Non-mammalian hosts, such as birds, have also been reported to be infected with the pathogenic form of "Candidatus Coxiella avium". This research increases the list of tick species that have been found with Coxiella-like bacteria in Thailand.

Methods: A total of 69 ticks were collected from 27 domestic fowl (Gallus gallus domesticus), 2 jungle fowl (Gallus gallus) and 3 Siamese firebacks (Lophura diardi) at 10 locations (provinces) in Thailand. Ticks were identified and PCR was used to amplify Coxiella bacteria 16S rRNA, groEL and rpoB genes from the extracted tick DNA. MEGA6 was used to construct phylogenetic trees via a Maximum Likelihood method.

Results: The phylogenetic analysis based on the 16S rRNA gene showed that the Coxiella sequences detected in this study grouped in the same clade with Coxiella sequences from the same tick genus (or species) reported previously. In contrast, rpoB gene of the Coxiella bacteria detected in this study did not cluster together with the same tick genus reported previously. Instead, they clustered by geographical distribution (Thai cluster and Malaysian cluster). In addition, phylogenetic analysis of the groEL gene (the chaperonin family) showed that all Coxiella bacteria found in this study were grouped in the same clade (three sister groups).

Conclusions: To our knowledge, we found for the first time rpoB genes of Coxiella-like bacteria in Haemaphysalis wellingtoni ticks forming two distinct clades by phylogenetic analysis. This may be indicative of a horizontal gene transfer event.
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http://dx.doi.org/10.1186/s13071-018-3259-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6307260PMC
December 2018

Pseudomonas aeruginosa glutathione biosynthesis genes play multiple roles in stress protection, bacterial virulence and biofilm formation.

PLoS One 2018 16;13(10):e0205815. Epub 2018 Oct 16.

Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand.

Pseudomonas aeruginosa PAO1 contains gshA and gshB genes, which encode enzymes involved in glutathione (GSH) biosynthesis. Challenging P. aeruginosa with hydrogen peroxide, cumene hydroperoxide, and t-butyl hydroperoxide increased the expression of gshA and gshB. The physiological roles of these genes in P. aeruginosa oxidative stress, bacterial virulence, and biofilm formation were examined using P. aeruginosa ΔgshA, ΔgshB, and double ΔgshAΔgshB mutant strains. These mutants exhibited significantly increased susceptibility to methyl viologen, thiol-depleting agent, and methylglyoxal compared to PAO1. Expression of functional gshA, gshB or exogenous supplementation with GSH complemented these phenotypes, which indicates that the observed mutant phenotypes arose from their inability to produce GSH. Virulence assays using a Drosophila melanogaster model revealed that the ΔgshA, ΔgshB and double ΔgshAΔgshB mutants exhibited attenuated virulence phenotypes. An analysis of virulence factors, including pyocyanin, pyoverdine, and cell motility (swimming and twitching), showed that these levels were reduced in these gsh mutants compared to PAO1. In contrast, biofilm formation increased in mutants. These data indicate that the GSH product and the genes responsible for GSH synthesis play multiple crucial roles in oxidative stress protection, bacterial virulence and biofilm formation in P. aeruginosa.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0205815PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6191110PMC
April 2019

Phylogenetic studies of bacteria (Rickettsia, Coxiella, and Anaplasma) in Amblyomma and Dermacentor ticks in Thailand and their co-infection.

Ticks Tick Borne Dis 2018 05 27;9(4):963-971. Epub 2018 Mar 27.

Biodiversity Research Cluster, Department of Biology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok, Thailand; Center of Excellence for Vectors and Vector-Borne Diseases, Faculty of Science, Mahidol University at Salaya, Phutthamonthon 4 Road, Nakhon Pathom, Thailand. Electronic address:

In this study, we attempted to detect Rickettsia, Coxiella and Anaplasma bacteria in one hundred and fourteen-Dermacentor and thirty three-Amblyomma unfed adult ticks that were collected from under leaves along animal trails at different places across Thailand. PCR amplification was used to identify bacterial infection with general conserved sequences of bacteria. The results revealed single infection in Amblyomma testudinarium ticks with Rickettsia (24%) and Coxiella (6%). Anaplasma bacteria were often detected in Dermacentor auratus ticks (32%). Coxiella spp. were detected in Dermacentor atrosignatus (6%) and D. auratus ticks (3%) in this study. Moreover, we found co-infection by Coxiella and Rickettsia bacteria (39%) in Am. testudinarium. In contrast, D. atrosignatus ticks were co-infected with Coxiella and Anaplasma bacteria (3%) and Dermacentor compactus ticks were co-infected with Rickettsia and Anaplasma spp. (25%). Interestingly, Am. testudinarium ticks (12%) were found for the first time to exhibit triple infection by these three bacteria. Phylogenetic studies showed the rickettsiae from ticks causing both single and multiple infections had sequence similarity with spotted fever group rickettsial strains, including Rickettsia massilliae, R. raoultii and R. tamurae. In addition, the phylogenetic analysis of the 16S rRNA gene of Coxiella bacteria showed that they were closely grouped with Coxiella endosymbionts in both Dermacentor and Amblyomma. Moreover, the Anaplasma identified in a D. auratus tick was grouped in the same clade with the pathogenic bacterium Anaplasma phagocytophilum. Bacterial co-infections in Dermacentor and Amblyomma ticks may cause co-transmission of some tick-borne microorganisms (pathogen and endosymbiont, whether enhance or reduce) in humans and animals and they could affect medical and veterinary health.
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http://dx.doi.org/10.1016/j.ttbdis.2018.03.027DOI Listing
May 2018

The FinR-regulated essential gene fprA, encoding ferredoxin NADP+ reductase: Roles in superoxide-mediated stress protection and virulence of Pseudomonas aeruginosa.

PLoS One 2017 10;12(2):e0172071. Epub 2017 Feb 10.

Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand.

Pseudomonas aeruginosa has two genes encoding ferredoxin NADP(+) reductases, denoted fprA and fprB. We show here that P. aeruginosa fprA is an essential gene. However, the ΔfprA mutant could only be successfully constructed in PAO1 strains containing an extra copy of fprA on a mini-Tn7 vector integrated into the chromosome or carrying it on a temperature-sensitive plasmid. The strain containing an extra copy of the ferredoxin gene (fdx1) could suppress the essentiality of FprA. Other ferredoxin genes could not suppress the requirement for FprA, suggesting that Fdx1 mediates the essentiality of FprA. The expression of fprA was highly induced in response to treatments with a superoxide generator, paraquat, or sodium hypochlorite (NaOCl). The induction of fprA by these treatments depended on FinR, a LysR-family transcription regulator. In vivo and in vitro analysis suggested that oxidized FinR acted as a transcriptional activator of fprA expression by binding to its regulatory box, located 20 bases upstream of the fprA -35 promoter motif. This location of the FinR box also placed it between the -35 and -10 motifs of the finR promoter, where the reduced regulator functions as a repressor. Under uninduced conditions, binding of FinR repressed its own transcription but had no effect on fprA expression. Exposure to paraquat or NaOCl converted FinR to a transcriptional activator, leading to the expression of both fprA and finR. The ΔfinR mutant showed an increased paraquat sensitivity phenotype and attenuated virulence in the Drosophila melanogaster host model. These phenotypes could be complemented by high expression of fprA, indicating that the observed phenotypes of the ΔfinR mutant arose from the inability to up-regulate fprA expression. In addition, increased expression of fprB was unable to rescue essentiality of fprA or the superoxide-sensitive phenotype of the ΔfinR mutant, suggesting distinct mechanisms of the FprA and FprB enzymes.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0172071PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5302815PMC
August 2017

Borrelia sp. phylogenetically different from Lyme disease- and relapsing fever-related Borrelia spp. in Amblyomma varanense from Python reticulatus.

Parasit Vectors 2016 06 24;9(1):359. Epub 2016 Jun 24.

Biodiversity Research Cluster, Department of Biology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok, 10400, Thailand.

Background: Species of the genus Borrelia are causative agents of Lyme disease and relapsing fever. Lyme disease is the most commonly reported vector-borne disease in the northern hemisphere. However, in some parts of the world Lyme borreliosis and relapsing fever may be caused by novel Borrelia genotypes. Herein, we report the presence of a Borrelia sp. in an Amblyomma varanense collected from Python reticulatus.

Methods: Ticks were collected from snakes, identified to species level and examined by PCR for the presence of Borrelia spp. flaB and 16S rRNA genes. Phylogenetic trees were constructed using the neighbour-joining method.

Results: Three A. varanense ticks collected from P. reticulatus were positive for a unique Borrelia sp., which was phylogenetically divergent from both Lyme disease- and relapsing fever-associated Borrelia spp.

Conclusion: The results of this study suggest for the first time that there is a Borrelia sp. in A. varanense tick in the snake P. reticulatus that might be novel.
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http://dx.doi.org/10.1186/s13071-016-1629-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4920998PMC
June 2016

FRANCISELLA-LIKE ENDOSYMBIONT IN A TICK COLLECTED FROM A CHICKEN IN SOUTHERN THAILAND.

Southeast Asian J Trop Med Public Health 2016 Mar;47(2):245-9

Francisella is a genus of bacterial pathogens potentially lethal to humans. We report here for the first time a novel Francisella-like endosymbiont discovered in a hard-tick (Rhipicephalus sanguineus s.l.) obtained from a chicken (Gallus domesticus) in Thailand. The phylogenetic results indicate the 16S rDNA sequences of this Francisella bacterium form a unique clade with the Francisella-like endosymbiont of the tick species, Amblyomma varanense and Amblyomma helvolum, that have previously been found on snakes in Thailand. This species of Francisella is in a different group from the other Francisella-like endosymbionts previously reported from other countries. No Francisella was detected in Haemaphysalis wellingtoni ticks obtained from chickens in this study.
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March 2016

Molecular detection of Rickettsia, Anaplasma, Coxiella and Francisella bacteria in ticks collected from Artiodactyla in Thailand.

Ticks Tick Borne Dis 2016 07 23;7(5):678-689. Epub 2016 Feb 23.

Biodiversity Research Cluster, Department of Biology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand; Center of Excellence for Vectors and Vector-Borne Diseases, Faculty of Science, Mahidol University at Salaya, Phutthamonthon 4 Road, Nakhon Pathom 73170, Thailand; Department of Fundamental Science, Faculty of Science and Technology, Surindra Rajabhat University, Muang District, Surin 32000, Thailand. Electronic address:

A total of 79 ticks collected from Sambar deer (Cervus unicolor), Barking deer (Muntiacus muntjak) and Wild boar (Sus scrofa) were examined by PCR for the presence of Rickettsia, Anaplasma, Coxiella, and Francisella bacteria. Of the 79 ticks, 13% tested positive for Rickettsia, 15% tested positive for Anaplasma, 4% tested positive for Coxiella, and 3% tested positive for Francisella. Interestingly, triple infection with Anaplasma, Rickettsia and Francisella was determined in a Dermacentor auratus tick. Moreover, another triple infection with Rickettsia, Anaplasma, and Coxiella was found in a Haemaphysalis lagrangei tick. Double infection of Rickettsia with Coxiella was also detected in another H. lagrangei tick. From the phylogenetic analyses, we found a Rickettsia sp. with a close evolutionary relationship to Rickettsia bellii in the H. lagrangei tick. We also found the first evidence of a Rickettsia sp. that is closely related to Rickettsia tamurae in Rhipicephalus (Boophilus) microplus ticks from Thailand. H. lagrangei and Haemaphysalis obesa ticks collected from Sambar deer tested positive for Anaplasma species form the same clade with Anaplasma bovis. In contrast, other H. lagrangei ticks collected from Sambar deer and D. auratus ticks collected from Wild boar were also reported for the first time to be infected with an Anaplasma species that is closely related to Anaplasma platys. The phylogenetic analysis of the 16S rRNA gene of Coxiella bacteria revealed that Coxiella symbionts from H. lagrangei formed a distinctly different lineage from Coxiella burnetii (a human pathogen). Additionally, Francisella bacteria identified in D. auratus ticks were found to be distantly related to a group of pathogenic Francisella species. The identification of these bacteria in several feeding ticks suggests the risk of various emerging tick-borne diseases and endosymbionts in humans, wildlife, and domestic animals in Thailand.
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http://dx.doi.org/10.1016/j.ttbdis.2016.02.015DOI Listing
July 2016

Detection of Rickettsia and Anaplasma from hard ticks in Thailand.

J Vector Ecol 2015 Dec;40(2):262-8

Biodiversity Research Cluster, Department of Biology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok, 10400, Thailand.

We collected a total of 169 adult hard ticks and 120 nymphs from under the leaves of plants located along tourist nature trails in ten localities. The results present data examining the vector competence of ticks of different genera and the presence of Rickettsia and Anaplasma species. The ticks belonged to three genera, Amblyomma, Dermacentor, and Haemaphysalis, comprising 11 species. Rickettsia bacteria were detected at three collection sites, while Anaplasma bacteria were detected at only one site. Phylogenetic analysis revealed new rickettsia genotypes from Thailand that were closely related to Rickettsia tamurae, Rickettsia monacensis, and Rickettsia montana. This study was also the first to show that Anaplasma bacteria are found in Haemaphysalis shimoga ticks and are closely related evolutionarily to Anaplasma bovis. These results provide additional information for the geographical distribution of tick species and tick-borne bacteria in Thailand and can therefore be applied for ecotourism management.
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http://dx.doi.org/10.1111/jvec.12163DOI Listing
December 2015

Hepatozoon and Theileria species detected in ticks collected from mammals and snakes in Thailand.

Ticks Tick Borne Dis 2015 Apr 23;6(3):309-15. Epub 2015 Feb 23.

Biodiversity Research Cluster, Department of Biology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand; Center of Excellence for Vectors and Vector-Borne Diseases, Faculty of Science, Mahidol University at Salaya, Phutthamonthon 4 Road, Nakhon Pathom 73170, Thailand. Electronic address:

We report the detection of Hepatozoon and Theileria in 103 ticks from mammals and snakes in Thailand. By using a genus-specific 18S rRNA PCR, Hepatozoon and Theileria spp. were detected in 8% and 18%, respectively, of ticks (n=79) removed from mammals. Of the ticks removed from snakes (n=24), 96% were infected with Hepatozoon spp., but none were infected with Theileria. Phylogenetic analysis revealed that Hepatozoon spp. detected from Dermacentor astrosignatus and Dermacentor auratus ticks from Wild boar (Sus scrofa) formed a phylogenetic group with many isolates of Hepatozoon felis that were distantly related to a species group containing Hepatozoon canis and Hepatozoon americanum. In contrast, a phylogenetic analysis of the Hepatozoon sequences of snake ticks revealed that Hepatozoon spp. from Amblyomma varanense from King cobra (Ophiophagus hannah) and Amblyomma helvolum ticks from Indochinese rat snake (Ptyas korros), and Asiatic water snake (Xenochrophis piscator) are grouped with Hepatozoon spp. recently isolated from Monocellate cobras, Reticulated pythons and Burmese pythons, all of Thai origin, and with Hepatozoon sp. 774c that has been detected from a tick species obtained from Argus monitors in Australia. A phylogenetic analysis demonstrated that Theileria spp. from Rhipicephalus (Boophilus) microplus, Haemaphysalis obesa, and Haemaphysalis lagrangei ticks from Sambar deer (Cervus unicolor) cluster with the Theileria cervi isolates WU11 and 239, and Theileria sp. Iwate 141. We report for the first time a Hepatozoon species that shares genetic similarity with Hepatozoon felis found in Dermacentor astrosignatus and Dermacentor auratus ticks collected from Wild boars in Thailand. In addition, we found the presence of a Theileria cervi-like sp. which suggests the potential role of Haemaphysalis lagrangei as a Theileria vector in Thailand.
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http://dx.doi.org/10.1016/j.ttbdis.2015.02.003DOI Listing
April 2015

Detection of Coxiella-like endosymbiont in Haemaphysalis tick in Thailand.

Ticks Tick Borne Dis 2015 Feb 7;6(1):63-8. Epub 2014 Oct 7.

Biodiversity Research Cluster, Department of Biology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand; Center of Excellence for Vectors and Vector-Borne Diseases, Faculty of Science, Mahidol University at Salaya, Nakhon Pathom, Thailand. Electronic address:

In this study, we focused on the molecular detection of Coxiella-like bacteria using a PCR technique to identify Coxiella 16S rRNA sequences in Haemaphysalis tick samples (105 adults, 8 nymph pools and 19 larval pools). Seven Haemaphysalis species obtained from 5 locations in Thailand were evaluated in this work. Coxiella endosymbionts could be detected in samples representing all 3 growth stages examined. The results also revealed that only 4 of 7 tick species were positive for Coxiella-like endosymbiont: Haemaphysalis hystricis, Haemaphysalis lagrangei, Haemaphysalis obesa, and Haemaphysalis shimoga. Haemaphysalis shimoga demonstrated the highest percentage of Coxiella-like positive samples (58.33% with n=24), while Haemaphysalis hystricis had the lowest percentage; only 1 female tick was positive for Coxiella-like bacteria (n=6). Interestingly, the results indicated that female Haemaphysalis ticks tended to harbour Coxiella symbionts more frequently than male ticks (59.32% of females and 21.27% of males of all species studied). Phylogenetic analyses based on 16S rRNA sequences illustrated that Coxiella-like spp. from the same tick species always grouped in same clade, regardless of the location from which they were isolated. Moreover, a phylogenetic tree also showed that Coxiella-like endosymbionts from other genera (for example, the tick genus Rhipicephalus) formed a separate group compared to Coxiella-like symbionts in the genus Haemaphysalis. This suggests that a high amount of DNA sequence variation is present in Coxiella-like bacteria harboured by ticks.
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http://dx.doi.org/10.1016/j.ttbdis.2014.09.005DOI Listing
February 2015

Molecular detection of Rickettsia species in Amblyomma ticks collected from snakes in Thailand.

Ticks Tick Borne Dis 2014 Oct 11;5(6):632-40. Epub 2014 Jul 11.

Biodiversity Research Cluster, Department of Biology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand; Center of Excellence for Vectors and Vector-Borne Diseases, Faculty of Science, Mahidol University at Salaya, Phutthamonthon 4 Road, Nakhon Pathom 73170, Thailand. Electronic address:

Some reptile ticks are potential vectors of pathogens such as spotted fever group (SFG) rickettsiae. Here, we report for the first time in detail the molecular evidence, DNA sequences and phylogenetic studies, for the presence of Rickettsia spp. in Amblyomma ticks (Amblyomma helvolum and Amblyomma varanense) from snakes in Thailand. A total of 24 tick samples was collected from 4 snake species and identified. A phylogenetic analysis inferred from the partial sequences of the gltA gene indicated that the Rickettsia spp. from 2 Amblyomma helvolum and 1 Amblyomma varanense belong to the same group as the SFG rickettsiae, which are closely related to Rickettsia raoultii strains. In contrast, there was 1 Rickettsia sp. from Amblyomma helvolum grouped into the same clade with other SFG rickettsiae (Rickettsia tamurae, Rickettsia monacensis, and a Rickettsia endosymbiont of Amblyomma dubitatum from Brazil). However, another Rickettsia sp. from Amblyomma varanense was closely related to Rickettsia bellii and Rickettsia sp. strain RDa420 from Thailand. In addition, from phylogenetic results based on the 16S rRNA gene and a concatenated tree of the 3 genes (gltA, ompA, and ompB), we found what may be a novel SFG rickettsia species closely related to Rickettsia raoultii (from both Amblyomma varanense and Amblyomma helvolum). In conclusion, our findings are the first report on the presence of novel SFG rickettsiae in 2 snake tick species, Amblyomma varanense and Amblyomma helvolum in Thailand and in south-eastern Asia.
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http://dx.doi.org/10.1016/j.ttbdis.2014.04.013DOI Listing
October 2014

Phylogenetic relationships of Francisella-like endosymbionts detected in two species of Amblyomma from snakes in Thailand.

Ticks Tick Borne Dis 2014 Feb;5(1):29-32

Ticks are important vectors of several bacterial pathogens, including Francisella. In this study, a total of 24 adult ticks (Amblyomma varanense and Amblyomma helvolum) collected from 4 species of snake from 3 provinces of Thailand was screened for the presence of Francisella-like endosymbionts (FLEs) by PCR. FLEs were detected in 46% (11/24) of all ticks examined. A phylogenetic analysis of the 16S rDNA sequence indicated that the 11 distinct genotypes of FLEs amplified from A. varanense and A. helvolum (from Khon Kaen and Pichit provinces, respectively) are in the same group, along with other FLEs amplified from the other tick genera. Interestingly, these FLEs are closely related to, but distinct (different clade) from, the FLEs isolated from different tick species previously reported. This work represents the first report of Francisella spp. in snake ticks from Thailand.
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http://dx.doi.org/10.1016/j.ttbdis.2013.08.001DOI Listing
February 2014

Gene expression and physiological role of Pseudomonas aeruginosa methionine sulfoxide reductases during oxidative stress.

J Bacteriol 2013 Aug 17;195(15):3299-308. Epub 2013 May 17.

Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand.

Pseudomonas aeruginosa PAO1 has two differentially expressed methionine sulfoxide reductase genes: msrA (PA5018) and msrB (PA2827). The msrA gene is expressed constitutively at a high level throughout all growth phases, whereas msrB expression is highly induced by oxidative stress, such as sodium hypochlorite (NaOCl) treatment. Inactivation of either msrA or msrB or both genes (msrA msrB mutant) rendered the mutants less resistant than the parental PAO1 strain to oxidants such as NaOCl and H2O2. Unexpectedly, msr mutants have disparate resistance patterns when exposed to paraquat, a superoxide generator. The msrA mutant had a higher paraquat resistance level than the msrB mutant, which had a lower paraquat resistance level than the PAO1 strain. The expression levels of msrA showed an inverse correlation with the paraquat resistance level, and this atypical paraquat resistance pattern was not observed with msrB. Virulence testing using a Drosophila melanogaster model revealed that the msrA, msrB, and, to a greater extent, msrA msrB double mutants had an attenuated virulence phenotype. The data indicate that msrA and msrB are essential genes for oxidative stress protection and bacterial virulence. The pattern of expression and mutant phenotypes of P. aeruginosa msrA and msrB differ from previously characterized msr genes from other bacteria. Thus, as highly conserved genes, the msrA and msrB have diverse expression patterns and physiological roles that depend on the environmental niche where the bacteria thrive.
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http://dx.doi.org/10.1128/JB.00167-13DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3719549PMC
August 2013

Rickettsia sp. closely related to Rickettsia raoultii (Rickettsiales: Rickettsiaceae) in an Amblyomma helvolum (Acarina: Ixodidae) tick from a Varanus salvator (Squamata: Varanidae) in Thailand.

J Med Entomol 2013 Jan;50(1):217-20

Biodiversity Research Cluster, Department of Biology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand.

An engorged female Amblyomma helvolum Koch tick was removed from an adult Varanus salvator Laurenti lizard during field collection in Thailand. After using polymerase chain reaction to amplify three genes (16S rDNA, gltA, and OmpA), we discovered the presence of a Rickettsia sp. of the Spotted Fever Group. Phylogenetic analysis revealed that this Rickettsia sp. is closely related to Rickettsia raoultii Mediannikov. Therefore, we report herein for the first time the detection of a novel Spotted Fever Group Rickettsia in an Amblyomma helvolum from a Varanus salvator in Thailand.
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http://dx.doi.org/10.1603/me12010DOI Listing
January 2013

Hard ticks and their bacterial endosymbionts (or would be pathogens).

Folia Microbiol (Praha) 2013 Sep 22;58(5):419-28. Epub 2013 Jan 22.

Biodiversity Research Cluster, Department of Biology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok, 10400, Thailand.

The symbiotic microorganisms of arthropod vectors are highly significant from several points of view, partly due to their possible roles in the transmission of pathogenic causative agents by blood-sucking vectors. Although ticks are well studied because of their significance to human health, novel microbial associations remain to be described. This review summarises several endosymbiotic bacterial species in hard ticks from various parts of the world, including Coxiella-, Francisella-, Rickettsia- and Arsenophonus-like symbionts as well as Candidatus Midichloria mitochondrii and Wolbachia. New methodologies for the isolation and characterization of tick-associated bacteria will, in turn, encourage new strategies of tick control by studying their endosymbionts.
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http://dx.doi.org/10.1007/s12223-013-0222-1DOI Listing
September 2013

Bioaccumulation of heavy metals in water, sediments, aquatic plant and histopathological effects on the golden apple snail in Beung Boraphet reservoir, Thailand.

Ecotoxicol Environ Saf 2012 Dec 15;86:204-12. Epub 2012 Oct 15.

Department of Biology, Faculty of Science, Mahidol University, Rama VI Road, Rachadhavi, Bangkok 10400, Thailand.

Changes in the seasonal concentrations of heavy metals (Cu, Mn, Fe, Zn, Pb and Cd) were determined in water, sediments, snails (Pomacea canaliculata) and aquatic plants (Ipomoea aquatica) in three selected tributaries of the Beung Boraphet reservoir, Nakhon Sawan Province, central Thailand. Only Fe, Cu, Mn and Zn were detected by FAAS in all samples collected. The water quality of Beung Boraphet was medium clean with Fe, Mn, Cu and Zn concentrations well below internationally accepted limits. According to the criteria proposed for sediments by the EPA Region V, Zn and Mn concentrations were within the non-polluted range while Fe and Cu (wet season) concentrations fell into the class of severely polluted sediment. Both P. canaliculata and I. aquatica bioconcentrated more Mn in their tissues than were found in sediments, especially in the wet season. The results of Pearson correlation study and BCF values also indicated similar findings. Only Mn showed the importance of sediment-to-snail concentration and high BCF values in both snails and plants. P. canaliculata exposed to contaminated sediment for two months, showed higher accumulation of metals (Fe, Mn, Cu and Zn) in the digestive tracts and digestive glands than in the foot muscles. Histopathological changes included alterations in the epithelial lining of the digestive tracts, digestive glands and the gills. Loss of cilia and increase in mucous cells were observed in the digestive tracts and gills, while the digestive glands exhibited an increase of dark granules and basophilic cells, and dilation of digestive cells. The results indicated that both P. canaliculata and I. aquatica could be used as biomonitors of sedimentary metal contamination for the Beung Boraphet reservoir.
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http://dx.doi.org/10.1016/j.ecoenv.2012.09.018DOI Listing
December 2012

Detection of Rickettsia and a novel Haemaphysalis shimoga symbiont bacterium in ticks in Thailand.

Curr Microbiol 2011 May 12;62(5):1496-502. Epub 2011 Feb 12.

Department of Biology, Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand.

In this study, we identified two Haemaphysalis species present at the Khao Yai National Park in Thailand and investigated the presence of rickettsia in these ticks. A total of 166 Haemaphysalis specimens were collected randomly under leaves along visitor paths at five locations in the park. Male and female adults of two different Haemaphysalis species, H. shimoga and H. lagrangei, were identified. Polymerase chain reaction (PCR) analysis revealed Rickettsia bacteria in these two Haemaphysalis species; this study represents the first time such presence has been reported in Thailand. The infection rates of Rickettsia were in both H. shimoga (7.41%) and H. lagrangei (10.17%) at these locations in addition to two pools of Haemahysalis nymphs (28.57%). Furthermore, 25.93% of H. shimoga showed positive results that matched Haemaphysalis longicornis symbionts (92% sequence identity) and the Coxeilla burnetti 16S ribosomal RNA gene (90% sequence identity). We propose that this is a novel H. shimoga symbiont bacterium in Thailand and might be a novel Coxeilla-like agent or Coxeilla sp. found in H. shimoga. In contrast, we did not observe any Wolbachia bacteria, which also belong to the order Rickettsiales, in the same group of Haemaphysalis ticks. Furthermore, PCR was used to detect three other genera of bacteria, Anaplasma, Ehrlichia and Borrelia, none of which were identified in the Haemaphysalis ticks studied.
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http://dx.doi.org/10.1007/s00284-011-9887-3DOI Listing
May 2011

Saw palmetto extract induces nuclear heterogeneity in mice.

Environ Toxicol Pharmacol 2009 Jan 9;27(1):149-54. Epub 2008 Oct 9.

Department of Biology, Faculty of Science, Mahidol University, Rachadhavi Bangkok, Thailand.

Saw palmetto (SW), a phytotherapeutic compound used in the treatment of prostate disease, was examined for potential nuclear effects. SW extract was incorporated into a complete casein-based semisynthetic rodent chow at 0%, 0.1% and 1% SW. SW was fed to mice for 6 weeks, after which the mice received a single i/p injection of either the known genotoxic agent methyl methanesulfonate (MMS) in saline or just saline. Forty-eight hours after injection, blood and bone marrow were collected for flow cytometric analysis. A significant effect of MMS was observed in both male and female mice with respect to: an increase in nuclear heterogeneity in bone marrow cells as measured by the coefficient of variation of the G1 peak in a flow histogram (6.32 versus 4.8 in male mice, 7.0 versus 4.9 in female mice) and an increase in the number of micronucleated blood cells (3.4% versus 0.56% male mice, 3.1% versus 0.6 in female mice) indicating a positive genotoxic response. SW also appears to increase the heterogeneity of bone marrow nuclei in a dose dependent manner (0-5.1%, 0.1-5.5% and 1-5.7% in male mice, 0-5.7%, 0.1-6.0% and 1-6.2% in female mice) without a concomitant increase in blood cell micronuclei. These results indicate that SW is not genotoxic with respect to physical DNA damage and that the changes observed in the bone marrow are due to chromatin conformation modifications in the nuclei of in vivo treated mouse cells.
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http://dx.doi.org/10.1016/j.etap.2008.09.006DOI Listing
January 2009

Relative Wolbachia density of field-collected Aedes albopictus mosquitoes in Thailand.

J Vector Ecol 2008 Jun;33(1):173-7

Center for Vectors and Vector-Borne Diseases Faculty of Science, Mahidol University, Rama 6 Road, Bangkok 10400, Thailand.

Female Aedes albopictus mosquitoes from natural populations of different geographical regions of Thailand were collected and allowed to oviposit to determine relative Wolbachia A and Wolbachia B densities of their offspring (F1) by using real-time quantitative PCR (RTQ-PCR). An important aspect of this work is that all Aedes albopictus mosquitoes were collected from the field. Twenty-seven offspring were from diverse areas of Thailand (Songkhla, Konkaen, Chantaburi, and Kanchanaburi). The range of relative Wolbachia A density in F, mosquitoes was from 0.007 to 1250.78 (bacteria-to-host ratio), whereas relative Wolbachia B densities ranged from 0 to 348.2 (bacteria-to-host ratio). These data are in contrast to those from a previous study that showed a very low amount (less than 0.10) of both relative Wolbachia density types for laboratory strains. The percent transmission of Wolbachia density from mother to each individual offspring cannot be predicted and was not related to the sex of the F1. Obtaining confirmation for variations and unpredictable Wolbachia transmission load raises some concerns about using Wolbachia as a gene-driving system in nature for population replacement if Wolbachia density is involved in cytoplasmic incompatibility in this mosquito.
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http://dx.doi.org/10.3376/1081-1710(2008)33[173:rwdofa]2.0.co;2DOI Listing
June 2008