Cloning and expression of enterovirus 71 capsid protein 1 in a probiotic Bifidobacterium pseudocatenulatum.

This study investigated cloning and expression of enterovirus 71 viral capsid protein 1 (EV71-VP1) in Bifidobacterium pseudocatenulatum (B. pseudocatenulatum) M115. To achieve this, a codon-optimized gene coding for EV71-VP1 was analysed, designed, synthesized and cloned into a plasmid vector flanked by a transcriptional promoter and terminator sequences. The promoter was based on that of P919, a constitutive promoter of the gene encoding the large ribosomal protein of B. bifidum BGN4, while the terminator was based on that of the peptidase N gene of Lactococcus lactis. The construct was amplified in Escherichia coli XL1-blue and then transferred into B. pseudocatenulatum M115 by electrotransformation. Western blot analysis revealed that the EV71-VP1 was intracellularly expressed in B. pseudocatenulatum M115 under the control of the selected heterologous promoter. In addition, plasmid stability analysis showed the construct was maintained stably for more than 160 generations, enough for most future applications. The results derived from this study open the possibility to utilize the bacterium carrying a specific expression plasmid as cell factory for the production of proteins with high commercial and health-promoting value. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrated the first successful expression of a codon-optimized gene coding for enterovirus 71 viral capsid protein 1 (EV71-VP1) in Bifidobacterium pseudocatenulatum M115, a novel probiotic strain isolated from human intestines. The EV71-VP1 was constitutively expressed under the control of P919 promoter derived from B. bifidum BGN4 in the cytoplasm of bacterial cells supporting the use of heterologous promoter and terminator sequences for viral gene expression in Bifidobacterium species.

Genetic variation of Enterobius vermicularis among schoolchildren in Thailand.

Enterobiasis, caused by the nematode Enterobius vermicularis, is a common health problem among schoolchildren in Thailand. We provide the first molecular identification of this nematode from Thai schoolchildren and document genetic variation among E. vermicularis eggs using sequence analyses of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene and the nuclear ribosomal DNA second internal transcribed spacer (ITS2). A cross-sectional parasitological survey was conducted in schoolchildren (n = 491) in five regions of Thailand between May 2015 and December 2016. The diagnosis of Enterobius infection was made using the adhesive tape perianal swab technique. Enterobius eggs were recovered from 43 participants (8.75%). DNA was extracted from these eggs and the cox1 gene and partial ITS2 region amplified using the polymerase chain reaction (PCR). Nineteen amplified PCR products of the cox1 gene (441 bp) and 18 of the ITS2 region (623 bp) were subsequently sequenced. All sequences were identified as belonging to E. vermicularis based on database searches. Phylogenetic analysis and a median-joining network of available E. vermicularis cox1 sequences showed 66 haplotypes. We found haploclusters (types A and B) represented among the Thai sequences. Six haplotypes from Thailand fell into type A (of Nakano et al., 2006) (along with sequences from Japan and Korea) and five haplotypes into type B (with sequences from Japan, Iran, Czech Republic, Greece, Denmark and Sudan). The overall haplotype diversity (Hd) was 0.9888. Transmission of worms with type B haplotypes from primates to humans in Asia or from humans in Europe possibly occurs in Thailand.

Molecular differentiation of Trichinella spiralis, T. pseudospiralis, T. papuae and T. zimbabwensis by pyrosequencing.

Nematodes of the genus Trichinella which infect wildlife and domestic animals show a cosmopolitan distribution. These zoonotic parasites are the aetiological agents of a severe human disease, trichinellosis. Twelve taxa are recognized in the Trichinella genus, but they cannot be identified by morphology since they are sibling species/genotypes. For epidemiological studies, it is extremely important to identify each taxon since they have different distribution areas and host ranges. In the present study, polymerase chain reaction (PCR) amplification of the mitochondrial large subunit ribosomal RNA (lsu-RNA) gene coupled with a pyrosequencing technique was developed to distinguish among four Trichinella species: Trichinella spiralis, T. pseudospiralis, T. papuae and T. zimbabwensis. A PCR method was used to amplify the lsu-RNA of Trichinella sp. larvae in mouse muscles and single larvae collected from infected muscles by digestion. The results show that the four Trichinella species can be distinguished by using 26 nucleotides in the target region and the method is sensitive enough to identify individual larvae. The pyrosequencing provides a simple, rapid and high-throughput tool for the differentiation of Trichinella species.

Development of multiplex pyrosequencing for HLA-B*57:01 screening using single nucleotide polymorphism haplotype.

WHAT IS KNOWN AND OBJECTIVE: Abacavir (ABC) is a commonly used nucleoside reverse-transcriptase inhibitor with potent antiviral activity against HIV-1. The US Food and Drug Administration and international HIV treatment guidelines recommend HLA-B*57:01 screening before initiating treatment with ABC. The current standard method for HLA-B*57:01 screening is limited by its high-cost, time-consuming and labour-intensive procedure with the requirement of a specialized laboratory. Our study aims to develop a more reliable screening test by selecting rs3093726 as an additional single nucleotide polymorphism (SNP) to combine with rs2395029 for multiplex pyrosequencing development. It offers high-accuracy, cost-effective and rapid detection. METHODS: Multiplex pyrosequencing was developed for HLA-B*57:01 screening using rs2395029 and rs3093726 as a surrogate marker and tested in 130 Thai subjects in parallel with singleplex pyrosequencing of each SNP and the standard sequence-based method. RESULTS AND DISCUSSION: Multiplex pyrosequencing showed 100% concordance when compared with both singleplex pyrosequencing and standard sequence-based method. This method showed 100% of negative predictive value (NPV), positive predictive value (PPV), specificity and sensitivity. WHAT IS NEW AND CONCLUSION: Multiplex pyrosequencing is a powerful tool for HLA-B*57:01 screening using the rs2395029 and rs3093726 haplotype genotyping as surrogate marker for this HLA-B. The assay provides accurate, cost-effective and rapid detection of this haplotype. It can be applied for ABC hypersensitivity screening of the Thai population before initiating treatment with ABC.

Development of a real-time PCR assay with fluorophore-labelled hybridization probes for detection of Schistosoma mekongi in infected snails and rat feces.

Schistosoma mekongi, a blood-dwelling fluke, is a water-borne parasite that is found in communities along the lower Mekong River basin, i.e. Cambodia and Lao People's Democratic Republic. This study developed a real-time PCR assay combined with melting-curve analysis to detect S. mekongi in laboratory setting conditions, in experimentally infected snails, and in fecal samples of infected rats. The procedure is based on melting-curve analysis of a hybrid between an amplicon from S. mekongi mitochondrion sequence, the 260 bp sequence specific to S. mekongi, and specific fluorophore-labelled probes. This method could detect as little as a single cercaria artificially introduced into a pool of 10 non-infected snails, a single cercaria in filtered paper, and 2 eggs inoculated in 100 mg of non-infected rat feces. All S. mekongi-infected snails and fecal samples from infected rats were positive. Non-infected snails, non-infected rat feces, and genomic DNA of other parasites were negative. The method gave high sensitivity and specificity, and could be applied as a fast and reliable tool for cercarial location in water environments in endemic areas and for epidemiological studies and eradication programmes for intermediate hosts.

Circulating CD14(+) CD16(+) monocyte levels predict tissue invasive character of cholangiocarcinoma.

Chronic inflammation as a risk factor for cancer development is driven in part by monocyte/macrophages, which in many cancers exhibit pro-tumorigenic activity. In this study we identified elevation in CD14(+) CD16(+) , a minor blood monocyte subpopulation in cholangiocarcinoma (CCA) patients, compared to normal and biliary disease patient specimens. Tumour association was suggested by the observation that this elevated level decreased to normal after tumour resection. Moreover, the elevated level of CD14(+) CD16(+) monocytes in CCA patient blood correlated with degree of MAC387-positive (recent blood-derived macrophage migrant-specific marker) tumour-associated macrophage infiltration as determined by immunohistochemistry. These CD14(+) CD16(+) monocytes were suggested to enhance tumour progression as this subpopulation possesses (i) high expression of adhesion molecules (CD11c, CD49d, and CD54) and scavenger receptor (CD163), which enable them to adhere strongly to endothelial cells, and (ii) that peripheral blood monocytes from CCA patients express high levels of growth and angiogenic factor-related genes (epiregulin, VEGF-A and CXCL3). Elevation of peripheral CD14(+) CD16(+) monocyte levels was associated with features associated with poor prognosis CCA parameters (non-papillary type and high number of tissue macrophages). These data indicate that the CD14(+) CD16(+) monocytes from CCA patients with pro-tumorigenic characteristics may associate with rapid tumour progression and poor patient outcome. If confirmed in subsequent studies, the level of CD14(+) CD16(+) monocytes may serve as a marker for disease activity in CCA patients and serve as a target for pathogenic macrophage specific drug development.

Real-time fluorescence resonance energy transfer PCR with melting curve analysis for the detection of Opisthorchis viverrini in fish intermediate hosts.

A real-time fluorescence resonance energy transfer (FRET) PCR combined with a melting curve analysis was developed for the detection of Opisthorchis viverrini in its fish intermediate host, cyprinoid fishes. Real-time FRET PCR is based on a fluorescence melting curve analysis of a hybrid between an amplicon generated from a family of repeated DNA elements, the pOV-A6 specific probe sequence (Genbank Accession No. S80278), a 162 bp repeated sequence specific to O. viverrini, and specific fluorophore-labeled probes. The real-time FRET PCR could detect as little as a single metacercaria artificially inoculated in 30 fish samples. The O. viverrini infected fishes were distinguished from non-infected fishes and from the genomic DNA of other parasites by their melting temperature. Sensitivity and specificity of this method were both 100% in the laboratory setting and it outperformed the microscopic method on field-collected samples as well. Melting curve analysis is a rapid, accurate, and sensitive alternative for the specific detection of O. viverrini infected fishes. It allows a high throughput and can be performed on small samples. The assay has not only great potential for epidemiological surveys of fish intermediate hosts but it could also be adapted as screening tool for a range of foodborne parasites in freshwater fishes.

Genetic polymorphisms of CCL2 associated with susceptibility to latent tuberculous infection in Thailand.

BACKGROUND: The extent to which individuals exhibit genetic susceptibility to tuberculosis (TB) is still unclear. Genetic variations in chemokine genes might influence the early clearance of Mycobacterium tuberculosis, affecting TB susceptibility. OBJECTIVES: To study single nucleotide polymorphisms (SNPs) of chemokine genes CCL2, CXCL9, CXCL10 and CXCL11, and their association with TB susceptibility. DESIGN: Of 248 participants enrolled, 49 had active TB, 43 had latent tuberculous infection (LTBI) and 156 were non-infected, including 24 healthy controls with no known TB exposure. These populations were divided into two groups based on TB exposure: susceptible (n = 92) and resistant (early clearance) (n = 132). RESULTS: Only CCL2 SNPs (-2518A/G) were significantly associated with increased TB susceptibility. Based on adjusted multivariate analysis, persons with the GG genotype at this SNP were twice as susceptible to TB as those with the AA genotype (P = 0.018, OR 2.880, 95%CI 1.201-6.903). Risk of LTBI was three times higher among those with GG (P = 0.003, OR 3.358, 95%CI 1.525-7.396 for AA+AG vs. GG and P = 0.012, OR 3.706, 95%CI 1.340-10.254 for AA vs. GG). Persons with the GG genotype produced significantly lower CCL2 levels in response to M. tuberculosis antigen stimulation (AA+AG vs. GG, P = 0.038). CONCLUSION: The CCL2 polymorphism (-2518A/G) was associated with susceptibility to LTBI in a North-East Thai populations.

An epidemiological survey of female reproductive health status: gynecological complaints and sexually-transmitted diseases.

An epidemiological survey of gynecological and sexually-transmitted diseases was conducted in 4 villages of Narmpong district, Khon Kaen, Thailand. It was focused on the reproductive health status of rural women. A mobile gynecological clinic was set up to collect materials and data including demographic characteristics, physical examination and specimen collection. Vaginal swabs were examined by microscope, Gram staining, pH measurement, KOH test and bacteriological cultivation. Endocervical swabs were examined for Chlamydia trachomatis, herpes simplex virus (HSV) and human papilloma virus (HPV) by polymerase chain reaction. Papanicolaou's test was applied for diagnosis of cytological abnormalities. Blood was tested by RPR and TPHA and urine was tested by LED test. The chief complaint was dysmenorrhea (44.8%). The others ranging from 43.4-3.0% were lower abdominal pain to genital ulcer. Prevalence of C. trachomatis, C. albicans, T. vaginalis, T. pallidum and G. vaginalis were found in 4.6, 10.9, 5.1, 2.7 and 1.0% of 586 women and HSV and HPV were found in 6.4% and 1.4% of 110 women, respectively. The three pathogens. C. trachomatis, C. albicans and T. vaginalis, were frequently found among women in the age of 20-49 years. The number of marriages and sex partners in the past year had an association with C. trachomatis infection while vaginal pH > 4.5, marital status, number of marriages and itching of genitalia had an association with T. vaginalis infection.

Rapid diagnosis of tuberculous pleural effusion using polymerase chain reaction.

Between October 1998 and September 1999, 98 patients with symptomatic exudative lymphocytic pleural effusion were enrolled in our study to evaluate the diagnostic sensitivity of polymerase chain reaction (PCR) assay. The mean age was 53.3 years ranging from 18 to 78 years. There were 61 men and 37 women. Pleural fluid was sent for gram staining, AFB staining, aerobic culture, culture of Mycobacterium tuberculosis on LJ media, and cytology. Additional fluid was used for a PCR-assay of the 16 S-23 S rRNA gene spacer sequences and for a nested PCR of the 16 S rRNA gene as a blind control. In cases of free-flow pleural tapping, histopathological analysis was done on three pleural biopsies. Overall etiologies comprised malignancy 53.1%, tuberculosis 36.7%, lymphoma 2.0% and chronic nonspecific inflammation 8.2%. The sensitivity and specificity of AFB-staining were 6% and 79%, respectively; while cultures on LJ media were 17% and 100%, respectively. The sensitivity of the PCR-assay was 50% (95% CI: 40 to 60%) and the specificity was 61% (95 CI: 52 to 71%). When PCR was nested, the sensitivity was 72% (95% CI: 63 to 81%) and specificity was 53% (95% CI: 43 to 63%). Two thirds (26 of 36) of tuberculous pleural effusion cases underwent pleural biopsy, and 62% were diagnosed by histopathology. There were no complications from thoracocentesis or pleural biopsy in any of the patients. We concluded that PCR assay was more sensitive than AFB staining and mycobacteria culture for diagnosis tuberculous pleural effusion but its specificity was quite low.

p53 status and human papillomavirus infection in Thai women with cervical carcinoma.

Loss of p53 function has been implicated in a wide variety of human malignacies. Many studies suggest that in cervical carcinoma p53 function is inactivated either by gene mutation or by complex formation with E6 oncoprotein product of high-risk human papillomavirus (HPV). The aim of this study was to determine the status of HPV infection and p53 gene mutation as well as their correlation in cervical carcinomas. Formalin-fixed paraffin-embedded tissues of 12 cervicitis, 21 cervical intraepithelial neoplasia grade 3 (CIN 3) and 17 squamous cell carcinomas were determined for the presence of HPV using polymerase chain reaction (PCR) amplification and dot blot hybridization. The status of p53 mutations in exons 5-8 was evaluated by polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) and confirmed by direct nucleotide sequencing. HPV infections were detected in all CIN 3 and squamous cell carcinomas (100%). Mutations of p53 were present in 3 of 38 HPV-positive samples: one with an ATG-->TTG transversion (Met-->Leu) in codon 237 of exon 7; and the others with a TGC-->TGG transversion (Cys-->Trp) in codon 242 of exon 7, and a CGT-->CCT transversion (Arg-->Pro) in codon 273 of exon 8, respectively. Our findings show that the frequency of p53 mutation is low in primary cervical carcinoma and that the p53 gene mutation and HPV infection are not mutually exclusive events in the development of cervical cancer. Thus, other genetic events independent of p53 inactivation may also significantly contribute to the carcinogenesis of the uterine cervix.

Use of PCR-PIRA for screening of a point mutation at codon 12 in K-ras oncogene obtained from paraffin embedded tissue sections.

Among various methods which have been developed for facilitating the screening of point mutations in human genomic DNA, PCR-Primer Introduced Restriction Analysis (PCR-PIRA) is of particular interest due to its practicality and short procedure allowing detection of point mutations by simple restriction enzyme digestion directly after PCR amplification. However, one limitation of PCR-PIRA method is the absence of restriction sites in the region of detection, thus creation of the recognition site in primers has been introduced. Detection of a point mutation at codon 12 in K-ras oncogene by BstNI requires one base change in the primer sequence so that only the normal but not mutant PCR product will be digested by the enzyme. However, false positive results generated from undigested normal DNA sequence are always obtained. This effect is compounded when it is used to analyse mixed cell populations in paraffin embedded section of cancer cells. Assay of a mutant band generated from normal DNA by densitometric quantitation enabled the determination of background values and thereby eliminated false positive results. Samples with higher ratios between mutant and normal bands than the background one after the first PCR-PIRA would be subjected to the second PCR-PIRA in order to confirm the results. Screening of such mutations in cervical carcinomas from paraffin embedded sections using the above criteria should reduce misinterpretation of PCR-PIRA results.

Characterization of Pseudomonas pseudomallei antigens by SDS-polyacrylamide gel electrophoresis and western blot.

Immunological characterization of various Pseudomonas pseudomallei preparations was carried out by SDS-PAGE and Western blot using sera from infected humans and from patients with other bacterial infections. Somatic (SOM) and partially purified cell extracts (PCE) gave more complex SDS-PAGE patterns: M(r) ranged from 86 to 12.7 and 48 to 10 kDa, respectively. The culture-filtrated antigens (CF) from 3 different kinds of synthetic media consisted of fairly simple profiles with common bands M(r) of 40, 26 and 16 kDa. PCE and CF reacted specifically with infected human sera; SOM did not. The components with M(r) of 40 kDa in CF reacted consistently with all infected sera but failed to react with sera infected with Escherichia coli, Enterobacter spp., Klebsiella pneumoniae, Proteus mirabilis, Salmonella spp., Staphylococcus aureus, Streptococcus spp., Pseudomonas aeruginosa and P. stutzeri. This peptide was demonstrated to be a major component in CF thus suggesting its potential for development of immunodiagnostic methods for melioidosis.

Prevalence of toxoplasma antibodies in blood donors and pregnant women in Khon Kaen Province.

Serum samples from blood donors and pregnant women in Khon Kaen were examined for antibodies to Toxoplasma by an indirect hemagglutination and indirect fluorescent antibody techniques. It was found that 6.4 per cent of the blood donors were positive by the indirect hemagglutination and 6.2 per cent by indirect fluorescent antibody tests. The seroprevalence in pregnant women were 12.0 per cent by indirect hemagglutination and 4.7 per cent by indirect fluorescent antibody tests. The frequency distribution curves of indirect hemagglutination titers were unimodal in both the groups studied. From the basis of these findings, it was concluded that toxoplasmosis is not endemic in Khon Kaen and the transmission occurs at a very low level.

Geographic distribution and genetic compatibility among six karyotypic forms of Anopheles peditaeniatus (Diptera: Culicidae) in Thailand.

Fifty-three isolines of Anopheles peditaeniatus were established from individual wild-caught females collected from cow-baited traps in 17 provinces of Thailand. Three types of X (X1, X2, X3) and 6 types of Y (Y1,Y2, Y3, Y4, Y5, Y6) chromosomes were determined based on different amounts of major block(s) of heterochromatin. These sex chromosomes comprised 6 karyotypic forms designated as Forms A (X3, Y1), B (X1, X2, X3, Y2), C (X3, Y3), D (X1, X2, X3, Y4), E (X1, X2, X3,Y5) and F (X2, X3, Y6). Form F is a new metaphase karyotype discovered in this study and is commonly found in all regions. Form A was found only in Lampang province, whereas Form E is widespread throughout the country. Forms B, C and D were obtained from the northern, northeastern, western and southern regions. Crossing experiments among the 11 isoline colonies representing the 6 karyotypic forms of An. peditaeniatus indicated genetic compatibility yielding viable progenies and complete synapsis of salivary gland polytene chromosomes through to the F2-generations. The results suggested the conspecific nature of these karyotypic forms which were further supported by very low intraspecific variation (genetic distance = 0.000-0.003) of nucleotide sequences in ribosomal DNA (ITS2) and mitochondrial DNA (COI and COII).

Herpes simplex virus IgG Fc receptors induced using recombinant adenovirus vectors expressing glycoproteins E and I.

Evidence has been presented that herpes simplex virus (HSV) immunoglobulin (IgG) Fc receptors are composed of a complex of two glycoproteins, gE and gI. In previous studies, cells infected with HSV-1 mutants lacking either gE or gI bound lower levels of soluble IgG than cells infected with wild-type viruses suggesting that both gE and gI were required for IgG binding. We have reevaluated the Fc receptor activity of these mutants using a more sensitive assay involving IgG-coated erythrocytes and have found that cells infected with a gE- mutant HSV-1 did not bind IgG-coated erythrocytes whereas cells infected with a gI- mutant retained some Fc binding activity. To further study HSV-induced Fc receptors recombinant adenovirus vectors expressing gE or gI were constructed. Cells expressing gE alone bound both soluble IgG and IgG-coated red cells, although the binding was consistently lower than that observed with HSV-infected cells or cells expressing both gE and gI. Cells expressing only gI were unable to bind either soluble IgG or IgG-coated erythrocytes. These results support the conclusion that both gE and gI are required for full Fc receptor activity, although gE alone can bind IgG to a lesser extent.

N-acetyltransferase polymorphism in Thailand.

A series of 222 individuals from the northeastern provinces of Thailand were studied with respect to acetylator phenotypes. Among individuals of pure Thai descent 55.5% were rapid acetylators. The corresponding figure for Chinese was 66.0%. There were no significant differences between Thais and Chinese. The result shows a lower frequency of rapid acetylators in Thais than in previous reports on Thais.

Detection of herpes simplex virus type 2 Bgl II N fragment in paraffin-embedded cervical tissue sections using nested polymerase chain reaction.

To study the presence of transforming sequence Bgl II N of HSV-2 in cervical cancer tissues, we developed the nested polymerase chain reaction (PCR) for detecting such a sequence in paraffin-embedded cervical tissue sections. Samples derived from 46 patients with premalignant and malignant lesions were tested. The sequence was found in 20-25% of total cases tested but not observed in any of the normal healthy controls. This study also indicates that for the detection of HSV-2 Bgl II N sequence in cervical tissue, the nested PCR may be more reliable than the in situ hybridization method.