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Virulence genes and plasmid profiles in Rhodococcus equi isolates from domestic pigs and wild boars (Sus scrofa) in Brazil

Ribeiro, Marcio Garcia; Takai, Shinji; Guazzelli, Alessandro; Batista Lara, Gustavo Henrique; da Silva, Aristeu Vieira; Fernandes, Marta Catarina; Zeni Condas, Larissa Anuska; Siqueira, Amanda Keller; Salerno, Tatiana
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 478-481
ENG
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 06/59298-5; Processo FAPESP: 06/50406-0; The virulence genes and plasmid profiles of 23 Rhodococcus equi isolates from 258 lymph nodes from domestic pigs (129 nodes with lesions and 129 without lesions) and 120 lymph nodes from slaughtered wild boars (60 nodes with lesions and 60 without) were characterized. R. equi was obtained from 19 lymph nodes of domestic pigs, 17 with, and two without lesions, and from four lymph nodes with lesions, from wild boars. The 23 isolates were tested for the presence of vapA and vapB genes, responsible for the 15-17 and 20 kDa virulence-associated proteins, respectively, by PCR in order to characterize as virulent (VapA), intermediately virulent (VapB) and avirulent. Plasmid DNAs were isolated and analyzed by digestion with restriction endonucleases to estimate size and compare their polymorphisms. of the 19 domestic pigs strains, seven (36.8%) were avirulent and 12 (63.2%) were intermediately virulent, with the intermediately virulent isolates being plasmid types 8 (8 isolates), 10 (2 isolates), 1 (1 isolate) and 29 (1 isolate). The plasmid type of four strains isolated from wild boars was also intermediately virulent type 8. None of the domestic pigs and wild boar isolates showed the vapA gene. These findings demonstrate a high occurrence of plasmid type 8 in isolates from pigs and wild boars...

Evaluation of DNA polymorphisms amplified by arbitrary primers (RAPD) as genetically associated elements to differentiate virulent and non-virulent Paracoccidioides brasiliensis isolates

Motta, Teresa R.; Moreira-Filho, Carlos A.; Mendes, Rinaldo P.; Souza, Lenice R.; Sugizak, Maria F.; Baueb, Sonia; Calich, Vera L.G.; Vaz, Celideia A.C.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 151-157
ENG
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Randomly amplified polymorphic DNA (RAPD) analysis of 35 Paracoccidioides brasiliensis isolates was carried out to evaluate the correlation of RAPD profiles with the virulence degree or the type of the clinical manifestations of human paracoccidioidomycosis. The dendrogram presented two main groups sharing 64% genetic similarity. Group A included two isolates from patients with chronic paracoccidioidomycosis; group B comprised the following isolates showing 65% similarity: two non-virulent, six attenuated, five virulent, eight from patients with chronic paracoccidioidomycosis and two from patients with acute paracoccidioidomycosis. The virulent Pb18 isolate and six attenuated or non-virulent samples derived from it were genetically indistinguishable (100% of similarity). Thus, in our study, RAPD patterns could not discriminate among 35 P. brasiliensis isolates according to their differences either in the degree of virulence or in the type of the clinical manifestation of this fungal infection. © 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.

Use of Ribotyping and Hemolysin Activity To Identify Highly Virulent Streptococcus suis Type 2 Isolates†

Staats, Jacque J.; Plattner, Brandon L.; Nietfeld, Jerome; Dritz, Steve; Chengappa, M. M.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /01/1998 EN
Relevância na Pesquisa
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Nineteen Streptococcus suis type 2 isolates were evaluated for their virulence in pigs and mice. Of these, seven were determined to be highly virulent in pigs on the basis of clinical sign scores and gross pathology and histopathology results. Clinical sign scores correlated with gross pathology and histopathology scores at P equal to 0.004 and P equal to 0.009, respectively. The virulence of highly virulent isolates in pigs compared somewhat with virulence in mice, but the correlation was not significant. No correlation of virulence was noted among the moderately virulent and avirulent isolates in pigs and mice. Chromosomal DNAs from all S. suis isolates were evaluated by PstI, PvuII, EcoRI, and HaeIII restriction enzyme digestion followed by hybridization with a digoxigenin-11-dUTP-labeled cDNA probe transcribed from 16S and 23S rRNAs from Escherichia coli. The hybridization patterns (ribotypes) varied depending upon the enzyme used, but a significant number of isolates determined to be highly virulent in pigs had unique hybridization patterns compared with those of the moderately virulent and avirulent isolates (P = 0.002). In addition, hemolysin activity showed a high correlation to virulence (P = 0.00008) and ribotype (P = 0.002).

Virulence characteristics of clinical and environmental isolates of Vibrio vulnificus.

Stelma, G N; Reyes, A L; Peeler, J T; Johnson, C H; Spaulding, P L
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /09/1992 EN
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Twenty-four randomly selected clinical and environmental Vibrio vulnificus isolates were tested for virulence in iron-overloaded mice (250 mg of iron dextran per kg of body weight). The log10 50% lethal doses of 17 isolates were lower by greater than or equal to 3.5 log10 units in iron-overloaded mice than in control mice. These isolates were classified as virulent. The 50% lethal doses of these virulent isolates were also lower in mice that were immunosuppressed by treatment with cyclophosphamide (150 mg/kg). Four of the seven isolates initially classified as avirulent were virulent in mice that were simultaneously iron overloaded and immunosuppressed. These isolates were classified as moderately virulent. The remaining three isolates were avirulent under all conditions. The incidence of virulent strains among clinical and environmental isolates did not differ. The virulent isolates produced high titers of hemolysin, were resistant to inactivation by serum complement, produced phenolate siderophore, and utilized transferrin-bound iron. The moderately virulent isolates differed from the virulent isolates only in their increased sensitivity to inactivation by serum complement. The avirulent isolates differed from those of the other two classes in their inability to either produce significant amounts of phenolate siderophore or utilize transferrin-bound iron. A modified agar plate diffusion method for transferrin-bound iron utilization was developed to differentiate the two classes of virulent isolates from the avirulent isolates in vitro.

Characterization of virulent and avirulent A/chicken/Pennsylvania/83 influenza A viruses: potential role of defective interfering RNAs in nature.

Bean, W J; Kawaoka, Y; Wood, J M; Pearson, J E; Webster, R G
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1985 EN
Relevância na Pesquisa
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In April 1983, an influenza virus of low virulence appeared in chickens in Pennsylvania. Subsequently, in October 1983, the virus became virulent and caused high mortality in poultry. The causative agent has been identified as an influenza virus of the H5N2 serotype. The hemagglutinin is antigenically closely related to tern/South Africa/61 (H5N3) and the neuraminidase is similar to that from human H2N2 strains (e.g., A/Japan/305/57) and from some avian influenza virus strains (e.g., A/turkey/Mass/66 [H6N2]). Comparison of the genome RNAs of chicken/Penn with other influenza virus isolates by RNA-RNA hybridization indicated that all of the genes of this virus were closely related to those of various other influenza virus isolates from wild birds. Chickens infected with the virulent strain shed high concentrations of virus in their feces (10(7) 50% egg infective dose per g), and the virus was isolated from the albumin and yolk of eggs layed just before death. Virus was also isolated from house flies in chicken houses. Serological and virological studies showed that humans are not susceptible to infection with the virus, but can serve as short-term mechanical carriers. Analysis of the RNA of the viruses isolated in April and October by gel migration and RNA-RNA hybridization suggested that these strains were very closely related. Oligonucleotide mapping of the individual genes of virulent and avirulent strains showed a limited number of changes in the genome RNAs...

Use of a mouse model to evaluate clinical and environmental isolates of Sporothrix spp. from the largest U.S. epidemic of sporotrichosis.

Dixon, D M; Duncan, R A; Hurd, N J
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1992 EN
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Five clinical and 69 environmental isolates from the largest U.S. epidemic of sporotrichosis were evaluated in NYLAR male mice following intravenous injection of 5 x 10(6) to 2 x 10(8) conidia per mouse. The clinical isolates and eight environmental isolates produced 100% mortality in groups of three mice each between 12 and 24 days after injection. These virulent isolates grew at 37 degrees C, were dematiaceous by virtue of melanin (melanized) on permissive media (e.g., potato dextrose agar), produced ovoid conidia borne sympodially on lateral conidiophores and pleurogenously about the main hyphal axis, and were identified as Sporothrix schenckii. Two melanized environmental isolates that grew at 35 degrees C but not at 37 degrees C were not virulent and had subtle morphological differences from S. schenckii. The remaining environmental isolates were not melanized, were not virulent, and were not S. schenckii; five were identified as Ophiostoma stenoceras and the remainder were identified as Sporothrix spp. Quantitative organ cultures revealed that clinical isolates grew exponentially in livers and testes, in contrast to an isolate of O. stenoceras that was eliminated from liver, lung, and spleen but that persisted in the testes throughout the 14-day sample period. This model helped to confirm the identification of S. schenckii isolates obtained from the environment.

Catalase and superoxide dismutase activities in virulent and nonvirulent Staphylococcus aureus isolates.

Kanafani, H; Martin, S E
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1985 EN
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36.65%
Catalase and superoxide dismutase (SOD) activities of virulent and nonvirulent isolates of Staphylococcus aureus were compared. The mean value of catalase activity for intact cell suspensions was 2,773 +/- 1,049 Kat f units (Kat f is defined as the ratio of the velocity constant of catalase at 0 min to the protein content in grams per milliliter); that of nonvirulent isolates was 154 +/- 92 Kat f units. The mean value of the catalase activities for lysates of virulent isolates was 260 +/- 120 Kat f units, and that of nonvirulent isolates was 31 +/- 19 Kat f units. Catalase levels in intact cells as well as in cell lysates were significantly different for virulent than for nonvirulent S. aureus isolates (P less than 0.001). The mean value of SOD activities was 20.85 +/- 11.48 U (1 U is defined as the amount of SOD required to inhibit the rate of reduction of cytochrome c by 50%) for virulent cell lysates, compared with a mean of 5.39 +/- 2.89 U for nonvirulent cell lysates. The SOD levels in virulent and nonvirulent isolates were significantly different (P less than 0.001). The virulence of the S. aureus isolates was determined by comparing weight gains of neonatal mice injected with virulent or nonvirulent strains. The percent weight gain of neonatal mice injected with virulent isolates was significantly lower than that of those injected with nonvirulent isolates.

Differentiation of Highly Virulent Strains of Streptococcus suis Serotype 2 According to Glutamate Dehydrogenase Electrophoretic and Sequence Type ▿

Kutz, Russell; Okwumabua, Ogi
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
EN
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The glutamate dehydrogenase (GDH) enzymes of 19 Streptococcus suis serotype 2 strains, consisting of 18 swine isolates and 1 human clinical isolate from a geographically varied collection, were analyzed by activity staining on a nondenaturing gel. All seven (100%) of the highly virulent strains tested produced an electrophoretic type (ET) distinct from those of moderately virulent and nonvirulent strains. By PCR and nucleotide sequence determination, the gdh genes of the 19 strains and of 2 highly virulent strains involved in recent Chinese outbreaks yielded a 1,820-bp fragment containing an open reading frame of 1,344 nucleotides, which encodes a protein of 448 amino acid residues with a calculated molecular mass of approximately 49 kDa. The nucleotide sequences contained base pair differences, but most were silent. Cluster analysis of the deduced amino acid sequences separated the isolates into three groups. Group I (ETI) consisted of the seven highly virulent isolates and the two Chinese outbreak strains, containing Ala299-to-Ser, Glu305-to-Lys, and Glu330-to-Lys amino acid substitutions compared with groups II and III (ETII). Groups II and III consisted of moderately virulent and nonvirulent strains, which are separated from each other by Tyr72-to-Asp and Thr296-to-Ala substitutions. Gene exchange studies resulted in the change of ETI to ETII and vice versa. A spectrophotometric activity assay for GDH did not show significant differences between the groups. These results suggest that the GDH ETs and sequence types may serve as useful markers in predicting the pathogenic behavior of strains of this serotype and that the molecular basis for the observed differences in the ETs was amino acid substitutions and not deletion...

Reproduction of Virulent Isolates of Meloidogyne incognita on Susceptible and Mi-resistant Tomato

Castagnone-Sereno, P.; Bongiovanni, M.; Dalmasso, A.
Fonte: Society of Nematologists Publicador: Society of Nematologists
Tipo: Artigo de Revista Científica
Publicado em /09/1994 EN
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The reproductive potential of natural and laboratory-selected Meloidogyne incognita isolates virulent against the tomato Mi resistance gene, all derived from a single egg-mass, were compared when the nematodes were inoculated on susceptible and resistant tomato. Fewer second-stage juveniles (P = 0.01) of the two virulent populations selected under laboratory conditions matured to females on the resistant tomato compared to the susceptible cultivar. In contrast, no differences were found between the number of egg masses produced on the resistant versus the susceptible tomato by the two natural virulent isolates. No clear general trends concerning the fecundity of the females could be inferred from the comparative analysis of the numbers of eggs per egg mass x tomato cultivar combination. These observations suggested that the genetic changes induced under environmentally controlled nematode growth might be different from those occurring in natural Mi-resistance breaking biotypes grown without environmental control.

Reproduction of Mi-Virulent Meloidogyne incognita Isolates on Lycopersicon spp.

Huang, X.; McGiffen, M.; Kaloshian, I.
Fonte: Society of Nematologists Publicador: Society of Nematologists
Tipo: Artigo de Revista Científica
Publicado em /03/2004 EN
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36.51%
Selection of detectable numbers of Mi-virulent root-knot nematodes has necessitated a greater understanding of nematode responses to new sources of resistance. During the course of this research, we compared the reproduction of four geographically distinct Mi-virulent root-knot nematode isolates on three resistant accessions of Lycopersicon peruvianum. Each accession carried a different resistant gene, Mi-3, Mi-7, or Mi-8. All nematode isolates were verified as Meloidogyne incognita using diagnostic markers in the mitochondrial genome of the nematode. Reproduction of Mi-virulent isolates W1, 133 and HM, measured as eggs per g of root, was greatest on the Mi-7 carrying accession and least on the Mi-8 carrying accession. In general, Mi-3 behaved similar to the Mi-8 carrying accession. Reproduction of the four nematode isolates was also compared on both Mi and non-Mi-carrying L. esculentum cultivars and a susceptible L. peruvianum accession. Resistance mediated by Mi in L. esculentum still impacted the Mi-virulent nematodes with fewer eggs per g of root on the resistant cultivar (P ≤ 0.05). Preliminary histological studies suggests that Mi-8 resistance is mediated by a hypersensitive response, similar to Mi.

Protection of European domestic pigs from virulent African isolates of African swine fever virus by experimental immunisation

King, Katherine; Chapman, Dave; Argilaguet, Jordi M.; Fishbourne, Emma; Hutet, Evelyne; Cariolet, Roland; Hutchings, Geoff; Oura, Christopher A.L.; Netherton, Christopher L.; Moffat, Katy; Taylor, Geraldine; Le Potier, Marie-Frederique; Dixon, Linda K.; T
Fonte: Elsevier Science Publicador: Elsevier Science
Tipo: Artigo de Revista Científica
Publicado em 20/06/2011 EN
Relevância na Pesquisa
36.4%
African swine fever (ASF) is an acute haemorrhagic disease of domestic pigs for which there is currently no vaccine. We showed that experimental immunisation of pigs with the non-virulent OURT88/3 genotype I isolate from Portugal followed by the closely related virulent OURT88/1 genotype I isolate could confer protection against challenge with virulent isolates from Africa including the genotype I Benin 97/1 isolate and genotype X Uganda 1965 isolate. This immunisation strategy protected most pigs challenged with either Benin or Uganda from both disease and viraemia. Cross-protection was correlated with the ability of different ASFV isolates to stimulate immune lymphocytes from the OURT88/3 and OURT88/1 immunised pigs.

Highly Divergent Virulent Isolates of Newcastle Disease Virus from the Dominican Republic Are Members of a New Genotype That May Have Evolved Unnoticed for Over 2 Decades

Courtney, Sean C.; Susta, Leonardo; Gomez, Dejelia; Hines, Nichole L.; Pedersen, Janice C.; Brown, Corrie C.; Miller, Patti J.; Afonso, Claudio L.
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /02/2013 EN
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A Newcastle disease virus (NDV) outbreak in chickens was reported in the Dominican Republic in 2008. The complete genome of this isolate, chicken/DominicanRepublic(JuanLopez)/499-31/2008 (NDV-DR499-31/08), and the fusion proteins of three other related viruses from the Dominican Republic and Mexico were sequenced and phylogenetically analyzed. Genetically, these four isolates were highly distinct from all other currently known isolates of NDV, and together, they fulfill the newly established criteria for inclusion as a novel genotype of NDV (genotype XVI). The lack of any reported isolation of viruses related to this group since 1986 suggests that virulent viruses of this genotype may have evolved unnoticed for 22 years. The NDV-DR499-31/08 isolate had an intracerebral pathogenicity index (ICPI) score of 1.88, and sequencing of the fusion cleavage site identified multiple basic amino acids and a phenylalanine at position 117, indicating this isolate to be virulent. These results were further confirmed by a clinicopathological assessment in vivo. In 4-week-old chickens, NDV-DR499-31/08 behaved as a velogenic viscerotropic strain with systemic virus distribution and severe necrohemorrhagic lesions targeting mainly the intestine and the lymphoid organs. The clear phylogenetic relationship between the 2008...

Characterization of virulence profile, protein secretion and immunogenicity of different Sporothrix schenckii sensu stricto isolates compared with S. globosa and S. brasiliensis species

Fernandes, Geisa Ferreira; dos Santos, Priscila Oliveira; Rodrigues, Anderson Messias; Sasaki, Alexandre Augusto; Burger, Eva; de Camargo, Zoilo Pires
Fonte: Landes Bioscience Publicador: Landes Bioscience
Tipo: Artigo de Revista Científica
EN
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36.55%
A comparative study about protein secretion, immunogenicity and virulence was performed in order to characterize and to compare eight Sporothrix schenckii sensu stricto isolates. For virulence characterization, a murine model, based on survival assay and CFU counting was used. S. brasiliensis and S. globosa, a highly virulent and a non-virulent isolates, respectively were used as external controls. Exoantigen profiles showed different secreted molecules; the 46- and 60-kDa molecules were commonly secreted by all three species. The S. schenckii s. str. isolates could be classified as non-virulent or presenting low, medium or high virulence, based on survival times after infection and recovery of viable fungi. The humoral response profiles of mice infected with S. schenckii s. str., S. globosa and S. brasiliensis were heterogeneous; five virulent isolates (S. schenckii s. str., n = 4 and S. brasiliensis, n = 1) had in common the recognition of the 60-kDa molecule by their respective antisera, suggesting that this antigen may be involved in virulence. Furthermore, the 110-kDa molecule was secreted and recognized by antisera from four virulent isolates (S. schenckii s. str., n = 3 and S. brasiliensis, n = 1), so there is a possibility that this molecule is also related to virulence. Our findings reveal different degrees of virulence in S. schenckii s. str. isolates and suggest the correlation of protein secretion and immunogenicity with virulence of S. schenckii complex. These findings provide new insights into the pathogenesis of S. schenckii s. str. and improve the knowledge about immunogenicity and protein profiles in S. schenckii complex.

Spore Density and Viability of Entomopathogenic Fungal Isolates from Indonesia, and Their Virulence against Aphis gossypii Glover (Homoptera: Aphididae)

Herlinda, Siti
Fonte: Penerbit Universiti Sains Malaysia Publicador: Penerbit Universiti Sains Malaysia
Tipo: Artigo de Revista Científica
Publicado em /08/2010 EN
Relevância na Pesquisa
36.54%
The focus of this study was on quantifying fitness attributes, such as spore density and viability, and determining the virulence level against aphid (Aphis gossypii) nymphs of isolates from the fungal species Beauveria bassiana and Metarhizium anisopliae. The fungal isolates were obtained from several insects, including Plutella xylostella, Hypothenemus hampei, Bronstispa longissima, A. gossypii, Tenebrio molitor, and Leptocorisa acuta, that were collected from Indonesian islands, such as Sumatera, Java, and Sulawesi. Third instar aphid nymphs were inoculated via topical application of 106 conidia ml−1 of the entomopathogenic fungal isolates. All of the B. bassiana and M. anisopliae isolates could produce very dense spores. The M. anisopliae isolate MaAg, which was obtained from the aphid, had the highest spore density at 6.70 × 108 conidia ml−1. Among the B. bassiana isolates, the highest conidial viability belonged to isolate CPJW8, which was obtained from Chrysodeixis chalcites, with a 39% average viability. Among the M. anisopliae isolates, the highest viabilities belonged to the isolates MaAg and MaLa, which were obtained from L. acuta, with a 33% and 32% average viabilities, respectively. All of the B. bassiana and M. anisopliae isolates were virulent against aphid nymphs...

Genetic Diversity and Pathogenicity of Cylindrocarpon destructans Isolates Obtained from Korean Panax ginseng

Song, Jeong Young; Seo, Mun Won; Kim, Sun Ick; Nam, Myeong Hyeon; Lim, Hyoun Sub; Kim, Hong Gi
Fonte: The Korean Society of Mycology Publicador: The Korean Society of Mycology
Tipo: Artigo de Revista Científica
EN
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36.5%
We analyzed the genetic diversity of Cylindrocarpon destructans isolates obtained from Korean ginseng (i.e., Panax ginseng) roots by performing virulence tests and nuclear ribosomal gene internal transcribed spacer (ITS) and mitochondrial small subunit (mt SSU) rDNA sequence analysis. The phylogenetic relationship analysis performed using ITS DNA sequences and isolates from other hosts helped confirm that all the Korean C. destructans isolates belonged to Nectria/Neonectria radicicola complex. The results of in vivo and ex vivo virulence tests showed that the C. destructans isolates could be divided into two groups according to their distinctive difference in virulence and the genetic diversity. The highly virulent Korean isolates in pathogenicity group II (PG II), together with foreign isolates from P. ginseng and P. quinquefolius, formed a single group. The weakly virulent isolates in pathogenicity group I, together with the foreign isolates from other host plants, formed another group and exhibited a greater genetic diversity than the isolates of PG II, as confirmed by the mt SSU rDNA sequence analysis. In addition, as the weakly virulent Korean isolates were genetically very similar to the foreign isolates from other hosts, they were likely to originate from hosts other than the ginseng plants.

Genotyping Toxoplasma gondii from wildlife in Pennsylvania and identification of natural recombinants virulent to mice

Dubey, J.P.; Van Why, K.; Verma, S.K.; Choudhary, S.; Kwok, O.C.H.; Khan, A.; Behinke, M.S.; Sibley, L.D.; Ferreira, L.R.; Oliveira, S.; Weaver, M.; Stewart, R.; Su, C.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
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Recent studies indicated the predominance of Toxoplasma gondii haplogroup 12 in wildlife in USA. But still little is known of the genetic diversity of this parasite circulating in wildlife. In the present study, we tested coyotes (Canis latrans), red foxes (Vulpes vulpes), white-tailed deer (Odocoileus virginianus), and geese (Branta canadensis) from the state of Pennsylvania for T. gondii infection. Antibodies to T. gondii were found in 160 of 367 animals, including 92 (34.5%) of 266 coyotes, 49 (62.0%) of 79 white-tailed deer, 17 (85.0%) of 20 red fox, and two of two Canada geese tested by the modified agglutination test (cut off titer 1:25). Tissues from 105 seropositive animals were bioassayed in mice, and viable T. gondii was isolated from 29 animals, including 10 of 53 coyotes, 11 of 16 foxes, 7 of 49 deer, and one of one goose. DNA isolated from culture-derived tachyzoites of these isolates was characterized initially using multilocus PCR-RFLP markers. Nine genotypes were revealed, including ToxoDB PCR-RFLP #1 (4 isolates), #2 (2 isolates), #3 (4 isolates), #4 (6 isolates), #5 (4 isolates), #54 (1 isolate), #141 (1 isolate), #143 (1 isolate), and #216 (6 isolates), indicating high genetic diversity of T. gondii in wildlife in Pennsylvania. Pathogenicity of six T. gondii isolates (5 of #216 and #141) was determined in outbred Swiss Webster mice. Three of #216 and the #141 isolates were acute virulent to mice...

Genetic characterisation of Streptococcus pneumoniae serotype 1 isolates in relation to invasiveness.

Harvey, Richard Manuel
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2010
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Streptococcus pneumoniae (the pneumococcus) is one of the most significant causes of human mortality and morbidity, and is a leading cause of diseases such as pneumonia, invasive disease (including bacteraemia and meningitis [IPD]) and otitis media. However, the pneumococcus is more commonly carried asymptomatically within the nasopharynx. The likelihood of the pneumococcus progressing from asymptomatic carriage to IPD varies between strains, and is associated with certain serotypes and clones. In particular, serotype 1 strains have a high-attack rate as they readily progress from a state of transient carriage to IPD. Recently, a closely-related group of hypervirulent serotype 1 clones have been responsible for epidemics of IPD with unusually high mortality rates. In contrast, epidemic asymptomatic carriage of serotype 1 clones has been found in a number of remote indigenous communities in the Northern Territory of Australia. Such isolates of serotype 1 from asymptomatic carriage are unusual and provided a rare opportunity to perform genomic comparisons with invasive serotype 1 isolates in order to identify serotype-independent factors that contribute to differences in the invasive potential of the pneumococcus. Preliminary work using the non-invasive serotype 1 isolates from the Northern Territory and a collection of invasive human isolates of both indigenous and non-indigenous origin identified three virulence profiles that were non-invasive...

Hybrid Pathogenicity Island PAGI-5 Contributes to the Highly Virulent Phenotype of a Pseudomonas aeruginosa Isolate in Mammals▿ †

Battle, Scott E.; Meyer, Folker; Rello, Jordi; Kung, Vanderlene L.; Hauser, Alan R.
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
36.47%
Most known virulence determinants of Pseudomonas aeruginosa are remarkably conserved in this bacterium's core genome, yet individual strains differ significantly in virulence. One explanation for this discrepancy is that pathogenicity islands, regions of DNA found in some strains but not in others, contribute to the overall virulence of P. aeruginosa. Here we employed a strategy in which the virulence of a panel of P. aeruginosa isolates was tested in mouse and plant models of disease, and a highly virulent isolate, PSE9, was chosen for comparison by subtractive hybridization to a less virulent strain, PAO1. The resulting subtractive hybridization sequences were used as tags to identify genomic islands found in PSE9 but absent in PAO1. One 99-kb island, designated P. aeruginosa genomic island 5 (PAGI-5), was a hybrid of the known P. aeruginosa island PAPI-1 and novel sequences. Whereas the PAPI-1-like sequences were found in most tested isolates, the novel sequences were found only in the most virulent isolates. Deletional analysis confirmed that some of these novel sequences contributed to the highly virulent phenotype of PSE9. These results indicate that targeting highly virulent strains of P. aeruginosa may be a useful strategy for identifying pathogenicity islands and novel virulence determinants.

Aislamientos de Beauveria bassiana y Metarhizium anisopliae virulentos para el control del picudo del algodonero, Anthonomus grandis (Coleoptera: Curculionidae); Beauveria bassiana and Metarhizium anisopliae isolates virulent for the control of the boll weevil, Anthonomus grandis (Coleoptera: Curculionidae)

Nussenbaum, Ana Laura
Fonte: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires Publicador: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires
Tipo: info:eu-repo/semantics/doctoralThesis; tesis doctoral; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2014 SPA
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El picudo del algodonero, Anthonomus grandis Boheman (Coleoptera: Curculionidae), es considerado una de las plagas más importantes de algodón en América, presente en Argentina desde 1993. El objetivo general del trabajo fue seleccionar aislamientos nativos de los hongos entomopatógenos Beauveria bassiana y Metarhizium anisopliae (Ascomycota: Hypocreales) virulentos para el picudo del algodonero. Para ello se obtuvieron aislamientos nativos provenientes de muestras de suelo e insectos, así como cepas pertenecientes a la micoteca del Laboratorio de Hongos Entomopatógenos (IMYZA, INTA). Se evaluó la patogenicidad y virulencia de 28 aislamientos de M. anisopliae y 66 aislamientos de B. bassiana sobre adultos de picudo y se estudiaron los efectos subletales sobre la alimentación y oviposición producidos por estos hongos. Por otro lado, fueron evaluadas distintas características de los aislamientos seleccionados, como la compatibilidad con los insecticidas químicos utilizados en campo, el efecto conjunto de los insecticidas químicos y los aislamientos sobre la plaga, y la tolerancia a altas temperaturas de los aislamientos. Finalmente, se evaluaron parámetros de producción masiva de conidios de los aislamientos seleccionados y se realizaron evaluaciones en campo de las formulaciones experimentales. Los aislamientos de M. anisopliae (Ma 50 y Ma 20) resultaron los más virulentos donde la concentración letal media fue 1...

Humoral response of paracoccidioidomycosis sera in hamsters with different Venezuelan isolates

Spencer,Lilian M; Mateu,Guaniri; Magaldi,Sylvia; García,Fabiola; Mata-Essayag,Sofia
Fonte: Revista de Biología Tropical Publicador: Revista de Biología Tropical
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/09/2009 EN
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Humoral response of paracoccidioidomycosis sera in hamsters with different Venezuelan isolates. Paracoccidioidomycosis (PCM) is a progressive systemic mycosis caused by the fungus Paraccocidioides brasiliensis (Pb), endemic to Venezuela and Latin America. In this study, eight different Venezuelan isolates obtained from patients with PCM, were inoculated intraperitoneally in Syrian hamsters (Cricetus auratus) and studied by immune-serum. Each strain was collected by gently scraping the surface of the culture medium (Sabouraud Dextrose Agar) and suspended in 3ml of 0.15 M phosphate-buffered saline. The antigen obtained was called Paraccocidioides brasiliensis Crude Antigen (CAP). Immunoblotting results showed that the immune-sera from hamsters recognized at least 3 bands: one over 200 kDa, and two of 80 and 15-20 kDa. This study suggests that IgG anti-CAP can reveal a significant variability in the eight Venezuelan isolates. Sera from 88 infected hamsters were evaluated by ELISA with eight different CAPs and Western blot with CAP 37383. ELISA results showed that, the antigen of the virulent isolate 37383 had the highest percentage (38%) of positivity, while the non-virulent isolate 1458 had the lowest one (13.6%). Furthermore, scanning densitometry revealed that the isolate 37383 had less bands than the non-virulent isolates. These results suggest that the ELISA test with CAP 37383 can detect circulating antibodies...