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2.
Med Microbiol Immunol ; 209(2): 125-137, 2020 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-31811379

RESUMEN

The most promising means of controlling anthrax, a lethal zoonotic disease during the early infection stages, entail restricting the resilient infectious form, i.e., the spores from proliferating to replicating bacilli in the host. The extractible antigen (EA1), a major S-layer protein present on the vegetative cells and spores of Bacillus anthracis, is highly immunogenic and protects mice against lethal challenge upon immunization. In the present study, mice were immunized with r-EA1C, the C terminal crystallization domain of EA1, to generate a neutralizing monoclonal antibody EA752-862, that was evaluated for its anti-spore and anti-bacterial properties. The monoclonal antibody EA752-862 had a minimum inhibitory concentration of 0.08 mg/ml, was bactericidal at a concentration of 0.1 mg/ml and resulted in 100% survival of mice against challenge with B. anthracis vegetative cells. Bacterial cell lysis as observed by scanning electron microscopy and nucleic acid leakage assay could be attributed as a possible mechanism for the bactericidal property. The association of mAb EA752-862 with spores inhibits their subsequent germination to vegetative cells in vitro, enhances phagocytosis of the spores and killing of the vegetative cells within the macrophage, and subsequently resulted in 90% survival of mice upon B. anthracis Ames spore challenge. Therefore, owing to its anti-spore and bactericidal properties, the present study demonstrates mAb EA752-862 as an efficient neutralizing antibody that hinders the establishment of early infection before massive multiplication and toxin release takes place.


Asunto(s)
Carbunco/prevención & control , Antibacterianos/uso terapéutico , Anticuerpos Monoclonales/uso terapéutico , Bacillus anthracis/inmunología , Esporas Bacterianas/inmunología , Animales , Carbunco/inmunología , Antibacterianos/biosíntesis , Antibacterianos/química , Antibacterianos/farmacología , Anticuerpos Antibacterianos/biosíntesis , Anticuerpos Antibacterianos/química , Anticuerpos Antibacterianos/aislamiento & purificación , Anticuerpos Antibacterianos/farmacología , Anticuerpos Monoclonales/biosíntesis , Anticuerpos Monoclonales/química , Anticuerpos Monoclonales/farmacología , Anticuerpos Neutralizantes/biosíntesis , Anticuerpos Neutralizantes/química , Anticuerpos Neutralizantes/aislamiento & purificación , Anticuerpos Neutralizantes/farmacología , Antígenos Bacterianos/inmunología , Bacillus anthracis/efectos de los fármacos , Sitios de Unión , Femenino , Inmunización , Macrófagos/efectos de los fármacos , Macrófagos/inmunología , Ratones , Ratones Endogámicos BALB C , Pruebas de Sensibilidad Microbiana , Microscopía Electrónica de Rastreo , Fagocitosis/efectos de los fármacos , Fagocitosis/inmunología , Esporas Bacterianas/efectos de los fármacos
3.
Front Microbiol ; 6: 511, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26074899

RESUMEN

In the present study, generation and characterization of a highly specific monoclonal antibody (mAb) against Ochratoxin A (OTA) was undertaken. The generated mAb was further used to develop a simple, fast, and sensitive sandwich dot-ELISA (s-dot ELISA) method for detection of OTA from contaminated food grain samples. The limit of detection (LOD) of the developed enzyme-linked immunosorbent assay (ELISA) method was determined as 5.0 ng/mL of OTA. Developed method was more specific toward OTA and no cross reactivity was observed with the other tested mycotoxins such as deoxynivalenol, fumonisin B1, or aflatoxin B1. To assess the utility and reliability of the developed method, several field samples of maize, wheat and rice (n = 195) collected from different geographical regions of southern Karnataka region of India were evaluated for the OTA occurrence. Seventy two out of 195 samples (19 maize, 38 wheat, and 15 rice) were found to be contaminated by OTA by s-dot ELISA. The assay results were further co-evaluated with conventional analytical high-performance liquid chromatography (HPLC) method. Results of the s-dot ELISA are in concordance with HPLC except for three samples that were negative for OTA presence by s-dot ELISA but found positive by HPLC. Although positive by HPLC, the amount of OTA in the three samples was found to be lesser than the accepted levels (>5 µg/kg) of OTA presence in cereals. Therefore, in conclusion, the developed s-dot ELISA is a better alternative for routine cereal based food and feed analysis in diagnostic labs to check the presence of OTA over existing conventional culture based, tedious analytical methods.

4.
Braz J Microbiol ; 45(2): 667-76, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25242957

RESUMEN

Salmonella enterica and Shigella species are commonly associated with food and water borne infections leading to gastrointestinal diseases. The present work was undertaken to develop a sensitive and reliable PCR based detection system for simultaneous detection of Salmonella enterica and Shigella at species level. For this the conserved regions of specific genes namely ipaH1, ipaH, wbgZ, wzy and invA were targeted for detection of Shigella genus, S. flexneri, S. sonnei, S. boydii and Salmonella enterica respectively along with an internal amplification control (IAC). The results showed that twenty Salmonella and eleven Shigella spp., were accurately identified by the assay without showing non-specificity against closely related other Enterobacteriaceae organisms and also against other pathogens. Further evaluation of multiplex PCR was undertaken on 50 natural samples of chicken, eggs and poultry litter and results compared with conventional culture isolation and identification procedure. The multiplex PCR identified the presence of Salmonella and Shigella strains with a short pre-enrichment step of 5 h in peptone water and the same samples were processed by conventional procedures for comparison. Therefore, this reported multiplex PCR can serve as an alternative to the tedious time-consuming procedure of culture and identification in food safety laboratories.


Asunto(s)
Técnicas Bacteriológicas/métodos , Técnicas de Diagnóstico Molecular/métodos , Reacción en Cadena de la Polimerasa Multiplex/métodos , Salmonella enterica/aislamiento & purificación , Shigella/aislamiento & purificación , Animales , Pollos , Microbiología Ambiental , Microbiología de Alimentos , Humanos , Infecciones por Salmonella/microbiología , Salmonelosis Animal/microbiología , Sensibilidad y Especificidad
5.
J Food Sci Technol ; 51(9): 1920-8, 2014 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-25190847

RESUMEN

Fumonisins are one of the most agriculturally significant environmental toxins produced by Fusarium and Aspergillus species that grow on agricultural commodities in the field or during storage. Cereals contaminated with fumonisins causes serious loss to agricultural produce leads to health problems in humans and other farm animals. In the present study, polyclonal hyperimmune sera was raised against FB1 in rabbits immunized with FB1-keyhole limpet haemocyanin (KLH). Purified antibodies were used to establish a sensitive gold nanoparticle based immunochromatographic strip (ICG) for detecting FB1 levels in cereal grains. Effective on-site detection of FB1 was achieved by developing a rapid and sensitive pAb based ICG strip. This strip had a detection limit of 5 ng mL(-1) for FB1 in cereal samples and it could be completed within 3 min. Close examination of 150 cereal samples by ICG strip method revealed that 77 were fumonisin-positive. Results obtained by the developed method was further validated with well standardized HPLC method and results of strip method was correlated well with those obtained by HPLC method. In conclusion, the developed method was a better alternative for onsite detection of FB1 in cereal samples intended for human consumption to reduce risk of humans and other farm animals. The high level of FB1 concentrations recorded in present study warrants the need to develop an awareness creation programme to the farmers of India for safe handling of cereal grains at the time of harvesting and storage of grains.

6.
J Appl Microbiol ; 116(6): 1465-73, 2014 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-24905217

RESUMEN

AIM: To evaluate the potential of an intergeneric multidomain recombinant chimeric protein for the simultaneous detection of Bacillus anthracis, Yersinia pestis and Staphylococcal enterotoxin B. METHODS AND RESULTS: Truncated portions of protective antigen (pag) of B. anthracis, fraction 1 capsular antigen (F1) of Y. pestis and enterotoxin B (entB) of Staphylococcus aureus were PCR amplified and linked each other using ligation-dependent cloning. The fusion gene was codon-optimized for expression in Escherichia coli and encoded a 55 kDa recombinant PFE protein (rPFE). Hyperimmune antiserum raised against rPFE specifically reacted individually with the native PA of B. anthracis, F1 antigen of Y. pestis and SEB of S. aureus on Western blot analysis as well as in enzyme-linked immunosorbent assay (ELISA). For simultaneous detection of these three antigens from culture supernatants, common media consisting of BHI broth supplemented with 0·2% xylose were used. To assess the detection capability, a known number of these organisms (10(8) -10(2) CFU ml(-1)) were experimentally spiked on to the meat and blood samples, the polyclonal antibodies were again clearly able to identify all three target proteins up to a dilution of 10(5) CFU ml(-1). CONCLUSIONS: This recombinant chimeric protein-based immunodetection approach may eventually provide advantages over PCR formats during onsite investigations of biological emergencies or even during routine testing by laboratories. SIGNIFICANCE AND IMPACT OF THE STUDY: The trivalent recombinant PFE protein could be a novel intervention for possible diagnosis/detection of potential biological agents simultaneously in environmental and clinical samples to reduce the responding time and minimize the impact of the bioattack.


Asunto(s)
Antígenos Bacterianos/aislamiento & purificación , Proteínas Bacterianas/aislamiento & purificación , Toxinas Bacterianas/aislamiento & purificación , Enterotoxinas/aislamiento & purificación , Sueros Inmunes/química , Animales , Bacillus anthracis , Western Blotting , Ensayo de Inmunoadsorción Enzimática , Femenino , Ratones Endogámicos BALB C , Reacción en Cadena de la Polimerasa , Proteínas Recombinantes/química , Staphylococcus aureus , Yersinia pestis
7.
Braz. j. microbiol ; 45(2): 667-676, Apr.-June 2014. ilus, tab
Artículo en Inglés | LILACS | ID: lil-723111

RESUMEN

Salmonella enterica and Shigella species are commonly associated with food and water borne infections leading to gastrointestinal diseases. The present work was undertaken to develop a sensitive and reliable PCR based detection system for simultaneous detection of Salmonella enterica and Shigella at species level. For this the conserved regions of specific genes namely ipaH1, ipaH, wbgZ, wzy and invA were targeted for detection of Shigella genus, S. flexneri, S. sonnei, S. boydii and Salmonella enterica respectively along with an internal amplification control (IAC). The results showed that twenty Salmonella and eleven Shigella spp., were accurately identified by the assay without showing non-specificity against closely related other Enterobacteriaceae organisms and also against other pathogens. Further evaluation of multiplex PCR was undertaken on 50 natural samples of chicken, eggs and poultry litter and results compared with conventional culture isolation and identification procedure. The multiplex PCR identified the presence of Salmonella and Shigella strains with a short pre-enrichment step of 5 h in peptone water and the same samples were processed by conventional procedures for comparison. Therefore, this reported multiplex PCR can serve as an alternative to the tedious time-consuming procedure of culture and identification in food safety laboratories.


Asunto(s)
Animales , Humanos , Técnicas Bacteriológicas/métodos , Técnicas de Diagnóstico Molecular/métodos , Reacción en Cadena de la Polimerasa Multiplex/métodos , Salmonella enterica/aislamiento & purificación , Shigella/aislamiento & purificación , Pollos , Microbiología Ambiental , Microbiología de Alimentos , Sensibilidad y Especificidad , Salmonelosis Animal/microbiología , Infecciones por Salmonella/microbiología
8.
J Food Sci Technol ; 51(6): 1218-22, 2014 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-24876660

RESUMEN

The current study reports the preparation and stabilization of novel functional drinks based on fruit and vegetable juices incorporating bacterial cellulose from Acetobacter xylinum. Pineapple, musk melon, carrot, tomato, beet root and a blend juice containing 20 % each of carrot and tomato juice with 60 % beet root juice has been studied. These juices have been stabilized over a storage period of 90 days at 28 °C, by the use of nisin and maintaining a low pH circumventing the need for any chemical preservatives or refrigeration. Instrumental color values have been correlated with the pigment concentrations present in the fresh as well as stored juices. There was 36, 72 and 60 % loss of total carotenoids in the case of carrot, pineapple and musk melon juices respectively while the lycopene content remained unchanged after 90 days of storage. The betanin content decreased 37 % in the case of beetroot juice and 25 % in the case of beetroot juice blended with carrot and tomato juices. Sensory analysis has revealed a clear preference for the beetroot blended mixed juice.

9.
J Appl Microbiol ; 116(2): 435-46, 2014 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-24119042

RESUMEN

AIMS: To develop a multiplex PCR assay coupled with selective enrichment step to detect major virulence-associated genes of enterotoxigenic Staphylococcus aureus and evaluate the same directly on contaminated food samples. METHODS AND RESULTS: The most important virulence-associated genes of Staph. aureus, which are commonly related to food safety issues, are targeted in this study. They include five major enterotoxigenic genes-sea, seb, sec, seg and sei, tst-which encodes TSST-1, mecA-which confer methicillin resistance and coa-for the enzyme coagulase along with an internal amplification control (IAC) to rule out false-negative result. A modified mannitol salt broth (MSB) supplemented with sodium pyruvate was used for selective enrichment of Staph. aureus from food samples prior to PCR. Evaluation of efficiency of different media revealed that enrichment of samples in modified MSB followed by PCR resulted in specific, sensitive and effective amplification of the targeted genes in comparison with other enrichment media. Incorporation of bovine serum albumin (BSA) as PCR enhancer improved the intensity of amplicons. The standardized multiplex PCR (mPCR) format was able to detect all the target genes at a bacterial load of 10(6) CFU ml(-1) in any sample. The PCR results were unequivocally correlated with the conventional methods when the mPCR format was assessed on a total of 91 Staph. aureus isolates. The entire assay was found to be effectual when evaluated on naturally contaminated food samples. CONCLUSIONS: The combinatorial approach involving selective enrichment followed by mPCR developed in this study was found to be effective for the detection of toxigenic Staph. aureus directly from various food sources. SIGNIFICANCE AND IMPACT OF THE STUDY: The developed format would find a promising application in early detection of food contaminations as well as in the diagnosis of food poisoning due to Staph. aureus.


Asunto(s)
Toxinas Bacterianas/metabolismo , Enterotoxinas/metabolismo , Contaminación de Alimentos , Microbiología de Alimentos , Reacción en Cadena de la Polimerasa Multiplex/métodos , Staphylococcus aureus/aislamiento & purificación , Animales , Coagulasa/genética , Medios de Cultivo/normas , Cartilla de ADN/normas , ADN Bacteriano/genética , Microbiología de Alimentos/instrumentación , Microbiología de Alimentos/métodos , Humanos , Reacción en Cadena de la Polimerasa Multiplex/normas , Sensibilidad y Especificidad , Staphylococcus aureus/genética , Staphylococcus aureus/patogenicidad , Virulencia/genética
10.
Lett Appl Microbiol ; 58(5): 414-22, 2014 May.
Artículo en Inglés | MEDLINE | ID: mdl-24313443

RESUMEN

UNLABELLED: Aspergillus section Flavi is a heterogeneous fungal cluster including some of the most economically important Aspergillus species. The section is comprised of toxigenic and nontoxigenic aspergilli that are phenotypically undistinguishable. The aim of this study was to develop a genetic marker specific to Aspergillus section Flavi on the whole. Based on inter-simple sequence repeat (ISSR) fingerprinting profiles of major Aspergillus section Flavi members, a sequence-characterized amplified region (SCAR) marker was identified. Primers were designed in the conserved regions of the SCAR marker and were utilized in a PCR for concurrent identification of major members of the section. The detection level of the SCAR-PCR was found to be 0·1 ng purified DNA, and when applied to 45 naturally contaminated food samples, 28 samples were found infected with Aspergillus section Flavi members. The present SCAR-PCR is rapid and less cumbersome unlike conventional identification techniques. SIGNIFICANCE AND IMPACT OF THE STUDY: Identification of Aspergillus section Flavi members is important owing to their impact on human health and economy. The ISSR-based SCAR-PCR developed in this study is superior over the other existing Aspergillus section Flavi detection systems due to its simplicity and minimal requirement of sample handling. This PCR could be a supplementary strategy to time-consuming and rather ambiguous conventional polyphasic detection techniques and a reliable tool for high-throughput sample analysis.


Asunto(s)
Aspergillus flavus/genética , Aspergillus flavus/aislamiento & purificación , Reacción en Cadena de la Polimerasa/métodos , Aflatoxinas/biosíntesis , Aspergillus flavus/clasificación , ADN de Hongos/genética , Humanos , Repeticiones de Microsatélite
11.
Braz J Microbiol ; 44(2): 401-6, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-24294228

RESUMEN

Hundred Fusarium culmorum strains, isolated from freshly harvested maize grain samples from Southern parts of India, were incubated in czapek-dox medium and analyzed for trichothecene (DON/NIV) production. The mPCR assay was standardized targeting trichothecene metabolic pathway genes viz., Tri6, Tri7, Tri13 for detection of trichothecene (DON/NIV) chemotypes and rDNA gene for specific detection of F. culmorum species. Primers for targeted genes were designed and used to predict whether these isolates could produce deoxynivalenol/nivalenol, 94 isolates were able to produce DON/NIV by mPCR assay. Chemical analysis of DON/NIV was carried out for mPCR positive isolates by high performance-thin layer chromatography (HPTLC). To check the practical usefulness of developed mPCR assay, 150 field samples of maize were evaluated and results were compared with conventional HPTLC method. Out of 150 samples, 34% samples stayed as a positive for NIV contamination whereas 44% were found to have deoxynivalenol contamination. Moreover, mPCR results are equivocally matched with the HPTLC chemical analysis for field samples. Chemotyping of F. culmorum isolates were reported for the first time from India, and highlights the important potential of F. culmorum to contaminate maize with DON/NIV.


Asunto(s)
Vías Biosintéticas , Fusarium/genética , Fusarium/metabolismo , Reacción en Cadena de la Polimerasa Multiplex , Tricotecenos/clasificación , Tricotecenos/metabolismo , Zea mays/microbiología , Cromatografía en Capa Delgada , Fusarium/aislamiento & purificación , Genotipo , Técnicas de Genotipaje , Incidencia , India
12.
J Appl Microbiol ; 114(3): 819-27, 2013 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-23216688

RESUMEN

AIM: To develop and evaluate a multiplex polymerase chain reaction assay (mPCR) for the concurrent detection of four major mycotoxin metabolic pathway genes, viz. nor1 (aflatoxin), Tri6 (trichothecene), FUM13 (fumonisin) and otanps (ochratoxin A). METHODS AND RESULTS: A mPCR assay with competitive internal amplification control, employing specific primers for each of the aforementioned four genes, was optimized and validated using 10 reference strains and 60 pure culture isolates. The standardized mPCR assay detected all four mycotoxin metabolic genes in artificially contaminated maize samples with a sensitivity of 2 × 10(3) CFU g(-1) for nor1-positive Aspergillus strains, Tri6 and FUM13-positive Fusarium strains and 2 × 10(4) CFU g(-1) for otanps-positive Penicillium strains. When the developed mPCR assay was applied to 40 natural foods, 35% (14 of 40) of the samples were contaminated with either one or more mycotoxins. The mPCR results were further evaluated with high-performance liquid chromatography (HPLC), and in general, both the methods provided unequivocal results. CONCLUSION: The current mPCR assay is a rapid and reliable tool for simultaneous specific and sensitive detection of aflatoxigenic Aspergillus strains, trichothecene- and fumonisin-producing Fusarium strains, and ochratoxigenic Penicillium species from naturally contaminated foods. SIGNIFICANCE AND IMPACT OF THE STUDY: This mPCR assay could be a supplementary strategy to current conventional mycotoxin analytical techniques such as thin-layer chromatography (TLC), high performance thin layer chromatography, HPLC, etc., and a reliable tool for high-throughput monitoring of major mycotoxin-producing fungi during the processing steps of food and feed commodities.


Asunto(s)
Aspergillus/aislamiento & purificación , Contaminación de Alimentos/análisis , Microbiología de Alimentos/métodos , Fusarium/aislamiento & purificación , Reacción en Cadena de la Polimerasa Multiplex/métodos , Penicillium/aislamiento & purificación , Aspergillus/genética , Cromatografía Líquida de Alta Presión , Cartilla de ADN , ADN de Hongos/genética , Fumonisinas/análisis , Fusarium/genética , Reacción en Cadena de la Polimerasa Multiplex/normas , Micotoxinas/análisis , Ocratoxinas/análisis , Penicillium/genética , Sensibilidad y Especificidad , Tricotecenos/análisis
13.
Braz. j. microbiol ; 44(2): 401-406, 2013. ilus, tab
Artículo en Inglés | LILACS | ID: lil-688577

RESUMEN

Hundred Fusarium culmorum strains, isolated from freshly harvested maize grain samples from Southern parts of India, were incubated in czapek-dox medium and analyzed for trichothecene (DON/NIV) production. The mPCR assay was standardized targeting trichothecene metabolic pathway genes viz., Tri6, Tri7, Tri13 for detection of trichothecene (DON/NIV) chemotypes and rDNA gene for specific detection of F. culmorum species. Primers for targeted genes were designed and used to predict whether these isolates could produce deoxynivalenol/nivalenol, 94 isolates were able to produce DON/NIV by mPCR assay. Chemical analysis of DON/NIV was carried out for mPCR positive isolates by high performance-thin layer chromatography (HPTLC). To check the practical usefulness of developed mPCR assay, 150 field samples of maize were evaluated and results were compared with conventional HPTLC method. Out of 150 samples, 34% samples stayed as a positive for NIV contamination whereas 44% were found to have deoxynivalenol contamination. Moreover, mPCR results are equivocally matched with the HPTLC chemical analysis for field samples. Chemotyping of F. culmorum isolates were reported for the first time from India, and highlights the important potential of F. culmorum to contaminate maize with DON/NIV.


Asunto(s)
Vías Biosintéticas , Fusarium/genética , Fusarium/metabolismo , Reacción en Cadena de la Polimerasa Multiplex , Tricotecenos/clasificación , Tricotecenos/metabolismo , Zea mays/microbiología , Cromatografía en Capa Delgada , Fusarium/aislamiento & purificación , Genotipo , Técnicas de Genotipaje , Incidencia , India
14.
World J Microbiol Biotechnol ; 28(7): 2465-71, 2012 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-22806151

RESUMEN

Monoclonal antibodies were generated against whole cell lysate of Burkholderia pseudomallei. Two out of 6 monoclonal antibodies were found specific and exhibited high affinity against B. pseudomallei, one of which, was utilized to develop sandwich ELISA for detection of specific B. pseudomallei antigen. Immunoassays were found to be specific as no reaction was observed with closely related Burkholderia and Pseudomonas species. Blood samples from experimentally infected mice were found positive for isolation till 4 days post infection (DPI) and ELISA till 10 DPI. One out of 40 sick animal serum samples tested in Thailand was found positive by sandwich ELISA that was earlier confirmed by isolation of B. pseudomallei. The results indicate the potentiality of the assay for its applicability in specific diagnosis of septicaemic melioidosis.


Asunto(s)
Infecciones por Burkholderia/diagnóstico , Burkholderia pseudomallei/inmunología , Animales , Anticuerpos Antibacterianos/inmunología , Anticuerpos Monoclonales/inmunología , Antígenos Bacterianos/inmunología , Burkholderia pseudomallei/patogenicidad , Ensayo de Inmunoadsorción Enzimática , Femenino , Ratones , Ratones Endogámicos BALB C
15.
World J Microbiol Biotechnol ; 28(2): 533-9, 2012 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-22806848

RESUMEN

Classical pathogenic strains of Yersinia enterocolitica produce a 17 kDa outer membrane protein, Ail (attachment-invasion locus), which mediates bacterial attachment to some cultures epithelial cell lines and invasion of others. In the present study, hybridomas were developed for the production of monoclonal antibodies (MAbs) against Ail protein of Y. enterocolitica. A set of five stabilized hybridoma cell lines were generated, of which, two MAbs, YEA 302 and YEA 303, exhibited specific reaction to the native Ail protein (17 kDa) present in whole cell lysate of Y. enterocolitica strains beside having reaction with rAil. The other three MAbs, YEA 5, 17 and 32, had some cross reactions with proteins other than Ail. Two out of five MAbs were IgG1, two were IgG2b and one in IgM in nature. MAbs (YEA 302 and YEA 303) did not show any cross-reaction with whole cell lysate of Brucella abortus, Vibrio cholerae, Salmonella typhimurium and Escherichia coli and other species of Enterobacteriaceae including Y. pestis in ELISA and Western blot analysis. The presence of Ail protein among the strains recovered from pork and milk samples was evaluated by these sets of MAbs and the results were compared with the duplex PCR. Collectively, the data suggest that these MAbs may have the potential for their use in the detection of pathogenic Y. enterocolitica reliably, rapidly and at a relatively low cost.


Asunto(s)
Anticuerpos Antibacterianos/inmunología , Anticuerpos Monoclonales/inmunología , Antígenos Bacterianos/inmunología , Proteínas Recombinantes/inmunología , Yersinia enterocolitica/inmunología , Antígenos Bacterianos/genética , Antígenos Bacterianos/metabolismo , Western Blotting , Electroforesis en Gel de Poliacrilamida , Ensayo de Inmunoadsorción Enzimática , Reacción en Cadena de la Polimerasa , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Yersinia enterocolitica/genética , Yersinia enterocolitica/metabolismo
16.
J Appl Microbiol ; 113(2): 448-58, 2012 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-22563989

RESUMEN

AIM: To evaluate an inter-generic recombinant alpha domain fusion protein for simultaneous detection and neutralization of Clostridium perfringens and Staphylococcus aureus alpha toxins. METHODS AND RESULTS: Truncated portions of clostridial and staphylococcal alpha haemolysin genes were PCR amplified and linked to each other through a hydrophilic flexible Glycine linker sequence using overlap-extension PCR to form a chimeric gene αCS. The recombinant αCS fusion protein was expressed and characterized for its toxicity, cell binding capacity and haemolysis inhibition properties. The fusion protein was nontoxic and effectively retarded staphylococcal alpha haemolysis, probably by competitively interacting with putative staphylococcal alpha haemolysin receptors on erythrocytes. Murine hyperimmune polysera raised against r-αCS specifically detected 42-kDa and 33-kDa proteins when culture supernatants of Cl. perfringens (clostridial alpha toxin) and Staph. aureus (staphylococcal alpha toxin), respectively, were analysed in Western blot. The polyclonal antisera effectively diminished the haemolytic action of both the wild-type toxins in vitro. CONCLUSIONS: The r-αCS fusion protein was nontoxic competitive inhibitor of staphylococcal alpha haemolysin. The protein elicited specific immune response against Cl. perfringens and Staph. aureus alpha toxins. The antisera also neutralized the toxicities of both the native wild-type toxins in vitro. SIGNIFICANCE OF THE STUDY: The bivalent recombinant αCS protein could be a novel intervention in the field of diagnostics and therapeutics against Cl. perfringens and Staph. aureus infections, particularly, in case of co-infections like gangrenous ischaemia, gangrenous mastitis, etc.


Asunto(s)
Toxinas Bacterianas/antagonistas & inhibidores , Proteínas de Unión al Calcio/antagonistas & inhibidores , Proteínas Hemolisinas/antagonistas & inhibidores , Proteínas Recombinantes de Fusión/farmacología , Fosfolipasas de Tipo C/antagonistas & inhibidores , Animales , Toxinas Bacterianas/genética , Western Blotting , Proteínas de Unión al Calcio/genética , Ensayo de Inmunoadsorción Enzimática , Eritrocitos/efectos de los fármacos , Femenino , Proteínas Hemolisinas/genética , Sueros Inmunes/farmacología , Ratones , Ratones Endogámicos BALB C , Reacción en Cadena de la Polimerasa , Proteínas Recombinantes de Fusión/genética , Fosfolipasas de Tipo C/genética
17.
Indian J Microbiol ; 52(3): 449-55, 2012 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-23997338

RESUMEN

Staphylococcal enterotoxin B (SEB) and toxic shock syndrome toxin-1 are the super antigens responsible for diseases such as staphylococcal food poisoning and toxic shock syndrome. At low serum concentrations, SEB can trigger toxic shock, profound hypotension and multi organ failure and hence is recognized as biowarfare molecule. In this study, a multidomain fusion protein (r-TE) was generated with specificity for SEB and toxic shock syndrome toxin (Tsst-1). The fusion gene comprising the conserved regions of seb and the tsst genes was codon-optimized for expression in Escherichia coli and encoded a 26 kDa recombinant multidomain chimeric protein (r-TE). Hyperimmune antiserum raised against r-TE specifically reacted with SEB (~28 kDa) and Tsst-1 (~22 kDa) components during Western blot analysis and by plate ELISA in confirmed toxin producing strains of S. aureus. The antigenicity of the SEB component of the r-TE protein was also confirmed using TECRA kit. The described procedure of creating a single protein molecule carrying components of two different toxins whilst still retaining the original antigenic determinants of individual toxins proved highly advantageous in the development of rapid, reliable and cost effective immunoassays and may also have the potential to serve as candidate molecule for vaccine studies.

19.
Indian J Microbiol ; 50(2): 139-44, 2010 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-23100820

RESUMEN

Aeromonas hydrophila and other aeromonads are ubiquitous organisms found in meat, vegetables, drinking water and various other food items. They cause diarrhea and extra-intestinal infections in normal and immunocompromised patients. The aim of the study was to develop a multiplex PCR assay for the detection of virulence-associated genes of Aeromonas including hemolysin (hlyA), aerolysin (aerA), glycerophospholipid-cholesterol acyl transferase (GCAT) alongwith a 16S rRNA gene. Internal amplification control (IAC), which was coamplified with aerA primers, was also included in this study. The results showed that all cultures of Aeromonas were accurately identified by the assay without showing non-specificity. A. hydrophila could be detected at a range of 10-50 CFU ml(-1) from experimentally spiked fish, chicken and milk samples following overnight enrichment in alkaline peptone water supplemented with 10 µg/ml ampicillin (APW-A) by this multiplex PCR (mPCR). When evaluated on a total of 74 naturally occurring food samples, four samples were identified to contain Aeromonas by mPCR. All these results were compared to the conventional culture, isolation and biochemical identification procedures. The high throughput and cost-effective mPCR method developed in this study could provide a powerful tool for detection of pathogenic Aeromonas spp. from food and environmental samples and in addition, the method has advantages in terms of specificity, sensitivity and ease of use compared to other reported PCR methods and DNA hybridization assays.

20.
Indian J Microbiol ; 50(2): 165-71, 2010 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-23100823

RESUMEN

Bacillus cereus, Bacillus thuringiensis and Bacillus anthracis are the major concerns for the food safety in terms of frequency and/or seriousness of the disease. Being members of the same group and sharing DNA homology to a larger extent, they do create problems when their specific detection/identification is attempted from different food and environmental sources. Numerous individual polymerase chain reaction (PCR) and few multiplex PCR (mPCR) methods have been employed to detect these organisms by targeting toxin genes but with lack of internal amplification control (IAC). Therefore, we attempted a mPCR with IAC for the detection of enterotoxic B. cereus group strains by selecting hbl A, nhe A and cyt K genes from B. cereus, indicative of the diarrheal potential and cry I A and pag genes, the plasmid borne phenotypic markers specific to B. thuringiensis and B. anthracis strains, respectively. Multiplex PCR assay validation was performed by simultaneous comparison with the results of single-target PCR assays and correlated to the classical conventional and biochemical identification of the organisms. The mPCR was able to detect as low as 10(1)-10(2) organisms per ml following overnight enrichment of spiked food samples (vegetable biriyani and milk) in buffered peptone water (BPW). The presence of these organisms could also be detected by mPCR in naturally contaminated samples of rice based dishes and milk. The high throughput and cost-effective mPCR method described could provide a powerful tool for simultaneous, rapid and reliable detection of enterotoxic B. cereus group organisms.

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