The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Ashok K. Chopra - One of the best experts on this subject based on the ideXlab platform.
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dna adenine methyltransferase influences the virulence of aeromonas hydrophila
Infection and Immunity, 2006Co-Authors: Tatiana E. Erova, Lakshmi Pillai, Amin A Fadl, Cristi L. Galindo, Shaofei Wang, Ashok K. ChopraAbstract:Among the various virulence factors produced by Aeromonas hydrophila, a type II secretion system (T2SS)-secreted cytotoxic enterotoxin (Act) and the T3SS are crucial in the pathogenesis of Aeromonas-associated infections. Our laboratory molecularly characterized both Act and the T3SS from a diarrheal isolate, SSU of A. hydrophila, and defined the role of some regulatory genes in modulating the biological effects of Act. In this study, we cloned, sequenced, and expressed the DNA adenine methyltransferase gene of A. hydrophila SSU (damAhSSU) in a T7 promoter-based vector system using Escherichia coli ER2566 as a host strain, which could alter the virulence potential of A. hydrophila. Recombinant Dam, designated as M.AhySSUDam, was produced as a histidine-tagged fusion protein and purified from an E. coli cell lysate using nickel affinity chromatography. The purified Dam had methyltransferase activity, based on its ability to transfer a methyl group from S-adenosyl-l-methionine to N6-methyladenine-free lambda DNA and to protect methylated lambda DNA from digestion with DpnII but not against the DpnI restriction enzyme. The dam gene was essential for the viability of the bacterium, and overproduction of Dam in A. hydrophila SSU, using an arabinose-inducible, PBAD promoter-based system, reduced the virulence of this pathogen. Specifically, overproduction of M.AhySSUDam decreased the motility of the bacterium by 58%. Likewise, the T3SS-associated cytotoxicity, as measured by the release of lactate dehydrogenase enzyme in murine macrophages infected with the Dam-overproducing strain, was diminished by 55% compared to that of a control A. hydrophila SSU strain harboring the pBAD vector alone. On the contrary, cytotoxic and hemolytic activities associated with Act as well as the protease activity in the culture supernatant of a Dam-overproducing strain were increased by 10-, 3-, and 2.4-fold, respectively, compared to those of the control A. hydrophila SSU strain. The Dam-overproducing strain was not lethal to mice (100% survival) when given by the intraperitoneal route at a dose twice that of the 50% lethal dose, which within 2 to 3 days killed 100% of the animals inoculated with the A. hydrophila control strain. Taken together, our data indicated alteration of A. hydrophila virulence by overproduction of Dam.
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dna adenine methyltransferase influences the virulence of aeromonas hydrophila
Infection and Immunity, 2006Co-Authors: Tatiana E. Erova, Lakshmi Pillai, Amin A Fadl, Cristi L. Galindo, Shaofei Wang, Ashok K. ChopraAbstract:Among the various virulence factors produced by Aeromonas hydrophila, a type II secretion system (T2SS)-secreted cytotoxic enterotoxin (Act) and the T3SS are crucial in the pathogenesis of Aeromonas-associated infections. Our laboratory molecularly characterized both Act and the T3SS from a diarrheal isolate, SSU of A. hydrophila, and defined the role of some regulatory genes in modulating the biological effects of Act. In this study, we cloned, sequenced, and expressed the DNA adenine methyltransferase gene of A. hydrophila SSU (damAhSSU) in a T7 promoter-based vector system using Escherichia coli ER2566 as a host strain, which could alter the virulence potential of A. hydrophila. Recombinant Dam, designated as M.AhySSUDam, was produced as a histidine-tagged fusion protein and purified from an E. coli cell lysate using nickel affinity chromatography. The purified Dam had methyltransferase activity, based on its ability to transfer a methyl group from S-adenosyl-l-methionine to N6-methyladenine-free lambda DNA and to protect methylated lambda DNA from digestion with DpnII but not against the DpnI restriction enzyme. The dam gene was essential for the viability of the bacterium, and overproduction of Dam in A. hydrophila SSU, using an arabinose-inducible, PBAD promoter-based system, reduced the virulence of this pathogen. Specifically, overproduction of M.AhySSUDam decreased the motility of the bacterium by 58%. Likewise, the T3SS-associated cytotoxicity, as measured by the release of lactate dehydrogenase enzyme in murine macrophages infected with the Dam-overproducing strain, was diminished by 55% compared to that of a control A. hydrophila SSU strain harboring the pBAD vector alone. On the contrary, cytotoxic and hemolytic activities associated with Act as well as the protease activity in the culture supernatant of a Dam-overproducing strain were increased by 10-, 3-, and 2.4-fold, respectively, compared to those of the control A. hydrophila SSU strain. The Dam-overproducing strain was not lethal to mice (100% survival) when given by the intraperitoneal route at a dose twice that of the 50% lethal dose, which within 2 to 3 days killed 100% of the animals inoculated with the A. hydrophila control strain. Taken together, our data indicated alteration of A. hydrophila virulence by overproduction of Dam.
Swagatika Sahu - One of the best experts on this subject based on the ideXlab platform.
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the effect of euglena viridis on immune response of rohu labeo rohita ham
Fish & Shellfish Immunology, 2009Co-Authors: Jyotirmayee Pradhan, Swagatika SahuAbstract:Abstract The study evaluated the effect of dietary doses of Euglena viridis on the immune response and disease resistance of Labeo rohita fingerlings against infection with the bacterial pathogen Aeromonas hydrophila . L. rohita fingerlings were fed with diet containing 0 (Control), 0.1 g, 0.5 g, 1.0 g Euglena powder kg −1 dry diet for 90 days. Biochemical (serum total protein, albumin, globulin, albumin:globulin ratio), haematological (WBC, RBC, haemoglobin content) and immunological (superoxide anion production, lysozyme, serum bactericidal activity) parameters of fish were examined after 30, 60 and 90 days of feeding. Fish were challenged with A. hydrophila 90 days post-feeding and mortalities were recorded over 10 days post-infection. The results demonstrate that fish fed with Euglena showed increased levels of superoxide anion production, lysozyme, serum bactericidal activity, serum protein and albumin ( P A. hydrophila less survivability was observed in the control group (56.65%) than the group fed the experimental diets. The group fed 0.5 g Euglena kg −1 dry diet showed the highest percentage survival (75%). These results indicate that Euglena stimulates the immunity and makes L. rohita more resistant to A. hydrophila infection.
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the effect of euglena viridis on immune response of rohu labeo rohita ham
Fish & Shellfish Immunology, 2009Co-Authors: Jyotirmayee Pradhan, Swagatika SahuAbstract:The study evaluated the effect of dietary doses of Euglena viridis on the immune response and disease resistance of Labeo rohita fingerlings against infection with the bacterial pathogen Aeromonas hydrophila. L. rohita fingerlings were fed with diet containing 0 (Control), 0.1 g, 0.5 g, 1.0 g Euglena powder kg(-1) dry diet for 90 days. Biochemical (serum total protein, albumin, globulin, albumin:globulin ratio), haematological (WBC, RBC, haemoglobin content) and immunological (superoxide anion production, lysozyme, serum bactericidal activity) parameters of fish were examined after 30, 60 and 90 days of feeding. Fish were challenged with A. hydrophila 90 days post-feeding and mortalities were recorded over 10 days post-infection. The results demonstrate that fish fed with Euglena showed increased levels of superoxide anion production, lysozyme, serum bactericidal activity, serum protein and albumin (P < 0.05) compared with the control group. Following challenge with A. hydrophila less survivability was observed in the control group (56.65%) than the group fed the experimental diets. The group fed 0.5 g Euglena kg(-1) dry diet showed the highest percentage survival (75%). These results indicate that Euglena stimulates the immunity and makes L. rohita more resistant to A. hydrophila infection.
Iddya Karunasagar - One of the best experts on this subject based on the ideXlab platform.
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recombinant aeromonas hydrophila outer membrane protein 48 omp48 induces a protective immune response against aeromonas hydrophila and edwardsiella tarda
Research in Microbiology, 2012Co-Authors: Rekha Khushiramani, Biswajit Maiti, Malathi Shekar, S K Girisha, Naviledasappa Akash, Appunni Deepanjali, Iddya KarunasagarAbstract:The gene coding for an outer membrane protein Omp48 of Aeromonas hydrophila isolated from an infected fish was cloned and sequenced. Analysis of nucleotide sequence showed the omp48 gene to be an adhesin encoding a protein of 426 amino acids with high identity to the omp48 gene of Aeromonas veronii, another fish pathogen. The gene belonged to the maltoporin group of porins and had high similarity to LamB porins of A. hydrophila, Aeromonas salmonicida and Vibrio parahaemolyticus. The expressed purified recombinant protein had an estimated molecular weight of 48 kDa. Further, rabbit hyperimmune sera against the recombinant protein reacted with A. hydrophila, Aeromonas sobria and A. veronii whole cell proteins at the region of 48 kDa, in western blotting. The recombinant protein was immunogenic in the fish Labeo rohita Hamilton. Fish immunized with recombinant protein, when challenged with virulent A. hydrophila and another bacterial fish pathogen, Edwardsiella tarda, showed relative percent survivals of 69 and 60, respectively. Our results suggest that Omp48 of A. hydrophila could be used as a potential vaccine candidate for protection not only against A. hydrophila infection, but also against the fish pathogen E. tarda.
Mark L. Lawrence - One of the best experts on this subject based on the ideXlab platform.
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Table_2_Comparative Genomics of Aeromonas hydrophila Secretion Systems and Mutational Analysis of hcp1 and vgrG1 Genes From T6SS.XLSX
2019Co-Authors: Hasan C. Tekedar, Attila Karsi, Jochen Blom, Hossam Abdelhamed, Salih Kumru, Mark L. LawrenceAbstract:Virulent Aeromonas hydrophila causes severe motile Aeromonas septicemia in warmwater fishes. In recent years, channel catfish farming in the U.S.A. and carp farming in China have been affected by virulent A. hydrophila, and genome comparisons revealed that these virulent A. hydrophila strains belong to the same clonal group. Bacterial secretion systems are often important virulence factors; in the current study, we investigated whether secretion systems contribute to the virulent phenotype of these strains. Thus, we conducted comparative secretion system analysis using 55 A. hydrophila genomes, including virulent A. hydrophila strains from U.S.A. and China. Interestingly, tight adherence (TaD) system is consistently encoded in all the vAh strains. The majority of U.S.A. isolates do not possess a complete type VI secretion system, but three core elements [tssD (hcp), tssH, and tssI (vgrG)] are encoded. On the other hand, Chinese isolates have a complete type VI secretion system operon. None of the virulent A. hydrophila isolates have a type III secretion system. Deletion of two genes encoding type VI secretion system proteins (hcp1 and vgrG1) from virulent A. hydrophila isolate ML09-119 reduced virulence 2.24-fold in catfish fingerlings compared to the parent strain ML09-119. By determining the distribution of genes encoding secretion systems in A. hydrophila strains, our study clarifies which systems may contribute to core A. hydrophila functions and which may contribute to more specialized adaptations such as virulence. Our study also clarifies the role of type VI secretion system in A. hydrophila virulence.
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Comparative Genomics of Aeromonas hydrophila Secretion Systems and Mutational Analysis of hcp1 and vgrG1 Genes From T6SS
Frontiers Media S.A., 2019Co-Authors: Hasan C. Tekedar, Attila Karsi, Jochen Blom, Hossam Abdelhamed, Salih Kumru, Mark L. LawrenceAbstract:Virulent Aeromonas hydrophila causes severe motile Aeromonas septicemia in warmwater fishes. In recent years, channel catfish farming in the U.S.A. and carp farming in China have been affected by virulent A. hydrophila, and genome comparisons revealed that these virulent A. hydrophila strains belong to the same clonal group. Bacterial secretion systems are often important virulence factors; in the current study, we investigated whether secretion systems contribute to the virulent phenotype of these strains. Thus, we conducted comparative secretion system analysis using 55 A. hydrophila genomes, including virulent A. hydrophila strains from U.S.A. and China. Interestingly, tight adherence (TaD) system is consistently encoded in all the vAh strains. The majority of U.S.A. isolates do not possess a complete type VI secretion system, but three core elements [tssD (hcp), tssH, and tssI (vgrG)] are encoded. On the other hand, Chinese isolates have a complete type VI secretion system operon. None of the virulent A. hydrophila isolates have a type III secretion system. Deletion of two genes encoding type VI secretion system proteins (hcp1 and vgrG1) from virulent A. hydrophila isolate ML09-119 reduced virulence 2.24-fold in catfish fingerlings compared to the parent strain ML09-119. By determining the distribution of genes encoding secretion systems in A. hydrophila strains, our study clarifies which systems may contribute to core A. hydrophila functions and which may contribute to more specialized adaptations such as virulence. Our study also clarifies the role of type VI secretion system in A. hydrophila virulence
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protective efficacy of four recombinant fimbrial proteins of virulent aeromonas hydrophila strain ml09 119 in channel catfish
Veterinary Microbiology, 2016Co-Authors: Hossam Abdelhamed, Attila Karsi, Seong Won Nho, Gokul Turaga, Michelle M Banes, Mark L. LawrenceAbstract:Aeromonas hydrophila is a reemerging pathogen of channel catfish (Ictalurus punctatus); recent outbreaks from 2009 to 2014 have caused the loss of more than 12 million pounds of market size catfish in Alabama and Mississippi. Genome sequencing revealed a clonal group of A. hydrophila isolates with unique genetic and phenotypic features that is highly pathogenic in channel catfish. Comparison of the genome sequence of a representative catfish isolate (ML09-119) from this virulent clonal group with lower virulence A. hydrophila isolates revealed four fimbrial proteins unique to strain ML09-119. In this work, we expressed and purified four A. hydrophila fimbrial proteins (FimA, Fim, MrfG, and FimOM) and assessed their ability to protect and stimulate protective immunity in channel catfish fingerlings against A. hydrophila ML09-119 infection for vaccine development. Our results showed catfish immunized with FimA, Fim, FimMrfG, and FimOM exhibited 59.83%, 95.41%, 85.72%, and 75.01% relative percent survival, respectively, after challenge with A. hydrophila strain ML09-119. Bacterial concentrations in liver, spleen, and anterior kidney were significantly (p < 0.05) lower in vaccinated fish compared to the non-vaccinated sham groups at 48 h post-infection. However, only the Fim immunized group showed a significantly higher antibody titer in comparison to the non-vaccinated treatment group (p < 0.05) at 21 days post-vaccination. Altogether, Fim and FimMrfG recombinant proteins have potential for vaccine development against virulent A. hydrophila infection.
Tatiana E. Erova - One of the best experts on this subject based on the ideXlab platform.
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dna adenine methyltransferase influences the virulence of aeromonas hydrophila
Infection and Immunity, 2006Co-Authors: Tatiana E. Erova, Lakshmi Pillai, Amin A Fadl, Cristi L. Galindo, Shaofei Wang, Ashok K. ChopraAbstract:Among the various virulence factors produced by Aeromonas hydrophila, a type II secretion system (T2SS)-secreted cytotoxic enterotoxin (Act) and the T3SS are crucial in the pathogenesis of Aeromonas-associated infections. Our laboratory molecularly characterized both Act and the T3SS from a diarrheal isolate, SSU of A. hydrophila, and defined the role of some regulatory genes in modulating the biological effects of Act. In this study, we cloned, sequenced, and expressed the DNA adenine methyltransferase gene of A. hydrophila SSU (damAhSSU) in a T7 promoter-based vector system using Escherichia coli ER2566 as a host strain, which could alter the virulence potential of A. hydrophila. Recombinant Dam, designated as M.AhySSUDam, was produced as a histidine-tagged fusion protein and purified from an E. coli cell lysate using nickel affinity chromatography. The purified Dam had methyltransferase activity, based on its ability to transfer a methyl group from S-adenosyl-l-methionine to N6-methyladenine-free lambda DNA and to protect methylated lambda DNA from digestion with DpnII but not against the DpnI restriction enzyme. The dam gene was essential for the viability of the bacterium, and overproduction of Dam in A. hydrophila SSU, using an arabinose-inducible, PBAD promoter-based system, reduced the virulence of this pathogen. Specifically, overproduction of M.AhySSUDam decreased the motility of the bacterium by 58%. Likewise, the T3SS-associated cytotoxicity, as measured by the release of lactate dehydrogenase enzyme in murine macrophages infected with the Dam-overproducing strain, was diminished by 55% compared to that of a control A. hydrophila SSU strain harboring the pBAD vector alone. On the contrary, cytotoxic and hemolytic activities associated with Act as well as the protease activity in the culture supernatant of a Dam-overproducing strain were increased by 10-, 3-, and 2.4-fold, respectively, compared to those of the control A. hydrophila SSU strain. The Dam-overproducing strain was not lethal to mice (100% survival) when given by the intraperitoneal route at a dose twice that of the 50% lethal dose, which within 2 to 3 days killed 100% of the animals inoculated with the A. hydrophila control strain. Taken together, our data indicated alteration of A. hydrophila virulence by overproduction of Dam.
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dna adenine methyltransferase influences the virulence of aeromonas hydrophila
Infection and Immunity, 2006Co-Authors: Tatiana E. Erova, Lakshmi Pillai, Amin A Fadl, Cristi L. Galindo, Shaofei Wang, Ashok K. ChopraAbstract:Among the various virulence factors produced by Aeromonas hydrophila, a type II secretion system (T2SS)-secreted cytotoxic enterotoxin (Act) and the T3SS are crucial in the pathogenesis of Aeromonas-associated infections. Our laboratory molecularly characterized both Act and the T3SS from a diarrheal isolate, SSU of A. hydrophila, and defined the role of some regulatory genes in modulating the biological effects of Act. In this study, we cloned, sequenced, and expressed the DNA adenine methyltransferase gene of A. hydrophila SSU (damAhSSU) in a T7 promoter-based vector system using Escherichia coli ER2566 as a host strain, which could alter the virulence potential of A. hydrophila. Recombinant Dam, designated as M.AhySSUDam, was produced as a histidine-tagged fusion protein and purified from an E. coli cell lysate using nickel affinity chromatography. The purified Dam had methyltransferase activity, based on its ability to transfer a methyl group from S-adenosyl-l-methionine to N6-methyladenine-free lambda DNA and to protect methylated lambda DNA from digestion with DpnII but not against the DpnI restriction enzyme. The dam gene was essential for the viability of the bacterium, and overproduction of Dam in A. hydrophila SSU, using an arabinose-inducible, PBAD promoter-based system, reduced the virulence of this pathogen. Specifically, overproduction of M.AhySSUDam decreased the motility of the bacterium by 58%. Likewise, the T3SS-associated cytotoxicity, as measured by the release of lactate dehydrogenase enzyme in murine macrophages infected with the Dam-overproducing strain, was diminished by 55% compared to that of a control A. hydrophila SSU strain harboring the pBAD vector alone. On the contrary, cytotoxic and hemolytic activities associated with Act as well as the protease activity in the culture supernatant of a Dam-overproducing strain were increased by 10-, 3-, and 2.4-fold, respectively, compared to those of the control A. hydrophila SSU strain. The Dam-overproducing strain was not lethal to mice (100% survival) when given by the intraperitoneal route at a dose twice that of the 50% lethal dose, which within 2 to 3 days killed 100% of the animals inoculated with the A. hydrophila control strain. Taken together, our data indicated alteration of A. hydrophila virulence by overproduction of Dam.
