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Acta Veterinaria Hungarica
Authors:
Katalin Jánosi
,
László Stipkovits
,
Róbert Glávits
,
Tamás Molnár
,
László Makrai
,
Miklós Gyuranecz
,
János Varga
, and
László Fodor

The purpose of this study was to develop and evaluate an aerosol infection method with Histophilus somni that closely resembles the natural way of infection of calves. Another aim was to compare the virulence of two H. somni strains by collecting clinical and postmortem data of experimentally infected and control animals. Seventeen conventionally reared 3-month-old calves were divided into three groups. Two groups of six animals each were exposed to suspensions containing H. somni on three consecutive days using a vaporiser mask. The third group of five animals was used as control. The data of individual clinical examination were recorded daily. All animals were exterminated, and gross pathology of all lungs was evaluated on the 15th day after the first infection. Both H. somni strains caused an increase of rectal temperature, respiratory signs, decrease of weight gain, and severe catarrhal bronchopneumonia in both infected groups. Although some chronic lesions were detected in the lungs of the control animals as well, the histopathological findings in the infected and control groups were different. H. somni was recultured from all lungs in the challenged groups but it could not be reisolated or detected by PCR examination in the control group. This is the first paper on aerosol challenge of calves with H. somni using repeated infection and verified by detailed pathological, bacteriological and histopathological examination. The infection method proved to be successful. There was no difference in the virulence of the two H. somni strains used in the trial.

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The association between putative virulence genes in Campylobacter jejuni clinical isolates, in vitro invasive capability and severity of infection is yet to be clearly described. We have characterized three virulence genes and correlated their presence with the severity of infection and in vitro invasiveness. We studied eight C. jejuni strains isolated from patients whose clinical data were scored to determine severity of infection. Cytolethal distending toxin (cdtB) , invasion associated marker (iam) and Campylobacter invasion antigen (ciaB) genes were detected by PCR and INT407 cells used for invasion assays. Two strains positive for all three genes were the most invasive and isolated from patients with the most severe infection. Four strains positive for two genes and two strains negative for all the three genes were identified. The two cdtB + ve / ciaB + ve strains were more invasive than the cdtB + ve / iam + ve strains. One of the cdtB ve / ciaB ve strains showed invasion levels similar to cdtB + ve / ciaB + ve strains, but the second strain had a non-invasive phenotype. The findings indicate a correlation between in vitro invasive capability, and the presence of all three genes. The pattern of association between invasiveness and molecular characterization suggests that the ciaB gene confers a more invasive capability.

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The virulence and pathogenicity of various types of Toxoplasma gondii differ considerably in mice. Recent studies have claimed that similar phenomenon was observed in humans, but no relevant studies have been performed to validate this finding. In addition, reports showing association between a given T. gondii type and outcomes of human infection yielded conflicting results. To provide a more precise estimation of the association and a more reliable conclusion on this subject, we performed this meta-analysis. Relevant literatures were identified in multiple databases and selected based on strict screening. T. gondii-type proportions among different severities of infection were calculated and compared using Fisher’s exact test. Pooled odds ratios (OR) were calculated. Our results showed that the difference among T. gondii-type proportions was significant (p < 0.0001). In addition, significant associations were detected between Type I strains infection and congenital toxoplasmosis (OR: 1.91, p = 0.0009), Type III strains infection and pulmonary toxoplasmosis (OR: 5.15, p = 0.04). In our subgroup analysis, Type I strains were significantly associated with cerebral toxoplasmosis in offspring (OR: 1.81, p = 0.02). This result indicated that different types of T. gondii exhibited different virulence and caused different outcomes in humans.

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Better vaccines and new therapeutic drugs could be a successful breakthrough against intracellular bacteria. M. tuberculosis ABC transporter ATPase (Rv0986) plays a role in mycobacterial virulence by inhibiting phagosome-lysosome fusion. Thus, it could be a potential vaccine candidate. C. pneumoniae another important intracellular bacterium possesses a protein named CpB0255, which is homologous with the mycobacterial Rv0986. The aim of this study was the cloning, over-expression and purification of CpB0255 ABC transporter ATPase protein to study its biological properties. The immunogenicity and protective effect of recombinant chlamydial ATPase protein combined with Alum adjuvant were investigated in mice. The immunization resulted in the reduction of the number of viable C. pneumoniae in the lungs after challenge. Our results confirm that chlamydial ATPase induces protective immunity in mice.

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The biological properties of bovine viral diarrhoea virus (BVDV) strain Oregon C24V were studied after intranasal and subcutaneous infection of pregnant sows. This virus strain is widely used in Hungary for immunising cattle against bovine viral diarrhoea (BVD). Based upon the results of the clinical, gross pathological, histopathological and virological examinations it can be established that the given strain caused asymptomatic infection and serological conversion in sows that were in the second third of gestation. The virus caused clinically apparent disease in some of the piglets born at term, which indicates that it had crossed the placenta. More than half (57%) of the live-born piglets died within 60 days of birth. The sows and their progeny did not shed the virus. BVDV infection has great differential diagnostic importance in pigs, as classical swine fever (CSF) virus strains of reduced virulence cause similar clinical symptoms and gross and histopathological changes.

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The possible role of fusariotoxin-fusaproliferin in Fusarium disease was investigated with respect to ultrastructure responses in the cells of maize leaves. The seedlings of resistant (Lucia) and susceptible (Pavla) maize cultivars were grown on two fusaproliferin concentrations (5 and 35 µg/mL −1 ). Only the higher concentration caused appearance of visible symptoms on the leaves. Structural changes of chloroplasts such as dilatation of grana thylakoids in the mesophyll chloroplasts, thylakoid disorganization, and an increased number of osmiophilic globules (plastoglobuli) in the stroma were observed in mesophyll and bundle sheath chloroplasts of both cultivars. The higher toxin concentration sporadically induced severe damage to the outer chloroplast membrane. The extent of ultrastructure disturbances depended on toxin concentration and it was greater in the susceptible cultivar Pavla. Fusaproliferin may be involved in Fusarium pathogenesis as a virulence factor or, by enhancing activity of some other toxins that might be concomitantly present in the diseased plants.

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Acta Phytopathologica et Entomologica Hungarica
Authors:
S. Babu
,
R. Nandakumar
,
S. Sriram
,
R. Jaisankar
,
V. Shanmugam
,
T. Raguchander
,
R. Samiyappan
, and
P. Balasubramania

Mutants of Rhizoctonia solani were developed using UV irradiation of the mycelia of isolate RS7, which is the field isolate causing sheath blight in rice. The mutants showed reduced virulence, as compared to RS7 in detached leaf sheath and intact rice plants. All the mutants produced some toxin but in varied quantities. The amount of toxin produced by the mu­tants was positively correlated with disease development on rice plants and detached leaf sheaths. The wild isolate RS7 and mutant RSU7 pro­duced more quantity of toxic material, which in turn related to severe sheath blight symptoms. Sclerotial production on the infected rice sheath also showed significant variation among the mutants and the virulent and less virulent isolates. SDS-PAGE analysis of the mycelial proteins show­ed many proteins of different molecular weights varying among mutants and wild isolate at different stages of mycelial growth. Correlation bet­ween reduction in toxin production and disease severity is statistically significant.

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Acta Microbiologica et Immunologica Hungarica
Authors:
Gabriella Spengler
,
Annamária Molnár
,
G. Klausz
,
Yvette Mándi
,
M. Kawase
,
N. Motohashi
, and
J. Molnár

The inhibition of bacterial motility was studied by a trifluoro methyl ketone derivative on two Escherichia coli strains (wild strain having a proton pump system and the proton pump-deficient mutant strain) and two Helicobacter pylori strains (clarithromycin susceptible and clarithromycin resistant). Evidence is presented of the inhibitory action of 1-(2-benzoxazolyl)-3,3,3-trifluoro-2-propanone (TF18) on the proton motive forces of the two bacterial strains by affecting the action of biological motor and proton efflux in the membranes. The swimming, the forward motion was more sensitive than the vibration or tumbling to the inhibition. We suppose that the inhibiton of bacterial motility is related to the virulence of bacteria: consequently the pathogenicity can be reduced in the presence of TF18.

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The present study reports on the location of major foci of footrot in goats in the Extremadura region of Spain by the determination of locally occurring strictly anaerobic microorganisms involved in the pathogenesis and development of this disease. The most commonly isolated microorganisms belonged to the genera Dichelobacter, Fusobacterium, Porphyromonas and Prevotella; these were found in conjunction with other species of minor importance. The species most frequently isolated were Fusobacterium necrophorum (40%), Dichelobacter nodosus (31.7%), Porphyromonas asaccharolytica (21.1%) and Prevotella melaninogenica (12.9%). Virulence factors identified in the isolated microorganisms included haemolysins, elastases and lecithinases, which enabled the organisms involved to initiate and/or aggravate the disease. Serotyping was performed for Dichelobacter nodosus isolates, since this species is responsible for triggering the process of infection. A and C were the most frequently isolated serovarieties (representing 40.7% and 25.9% of the cases, respectively).

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Acta Alimentaria
Authors:
R.D. Wang
,
Y.J. Deng
,
L.J. Sun
,
Y.L. Wang
,
Z.J. Fang
,
D.F. Sun
,
Q. Deng
, and
R. Gooneratne

Growth and haemolytic activity of several pathogenic Vibrio species were compared in egg-fried-rice with different egg ratios. Egg-fried-rice preparations with rice-to-egg ratios of 4:1, 1:1, and 1:4 were inoculated with either Vibrio parahaemolyticus, V. cholerae, V. vulnificus, or V. alginolyticus and incubated for 24 h. Cell number, thermostable direct haemolysin (TDH) activity, and total haemolytic activity were determined. The cell number and total haemolytic activity increased in all Vibrio strains after 24 h, and these were most marked in egg-fried-rice with the highest egg content (1:4 (rice:egg) ratio; P&lt;0.05). V. alginolyticus exhibited the maximal growth and V. parahaemolyticus the highest haemolytic activity, but only V. parahaemolyticus ATCC 33847, V. alginolyticus CAMT 21162, and V. alginolyticus HY 91101 showed TDH activity. Results suggest that lowering egg content in egg-fried-rice could reduce growth and virulence of Vibrio pathogens.

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