Horizontal gene transfer (HGT) plays a key role in the evolution of bacterial pathogens. The exchange of genetic material supplies prokaryotes with several fitness traits enhancing their adaptive response to environmental changes. Pathogenicity islands (PAIs) represent an important and in most cases already immobilized subset of the different vehicles for HGT. Encoding several virulence factors PAIs represent a major contribution to bacterial pathogenicity. Nonetheless, the transfer mechanisms of PAIs still remain elusive. We summarise the currently available data regarding the major ways of genetic mobilisation with a focus on the transfer of the
High-Pathogenicity Island (HPI).
Authors:Fiona Doohan, Chan Arunachalam, Shumei Jiang, Mojibur Khan, Damian Egan, Guillaume Erard, and Stephanie Walter
mycotoxin deoxynivalenol (DON) is a potent inhibitor of eukaryotic protein synthesis and acts as a virulence factor during infection of wheat heads. Some wheat genotypes can tolerate DON and resist its deleterious effects; others cannot. Transcriptome studies identified several genes up-regulated in spikelets of the DON-resistant wheat cultivar CM82036 in response to DON treatment. We will discuss how the finding presented herein and other recent findings contribute to the hypothesis that management of hormone homeostasis and alleviation of oxidative stress in DON-challenged wheat might facilitate cell survival and thereby retard fungal colonisation.
Authors:Mária Kelemen, Katalin Forgách, Judit Iván, V. Palya, T. Süveges, B. Tóth, and J. Mészáros
The appearance of very virulent strains of infectious bursal disease (IBD) virus at the end of the 1980s made it necessary to develop more effective immunization procedures. To facilitate this, the immunogenicity and the immunosuppressive effect of a mild (G-87), an intermediate (LIBD) and an intermediate-plus (IBDV 2512) IBDV strain were tested after the in ovo inoculation of 18-day-old SPF and broiler chicken embryos. It was established that no noteworthy difference existed between the immunized and the control embryos in hatching rate and hatching weight. The higher the virulence of the vaccine virus strain, the more severe damage it caused to the lymphocytes of the bursa of Fabricius. In SPF chickens, the haemagglutination inhibition (HI) titres induced by a Newcastle disease (ND) vaccine administered at day old decreased in inverse ratio to the virulence of the IBD vaccine strain, while in broiler chickens this was not observed. Despite the decrease of the HI titre, the level of protection did not decline, or did so only after the use of the ‘hot’ strain. SPF chickens immunized in ovo with a complex vaccine prepared from strain IBDV 2512 and IBD antibody showed the same protection against Newcastle disease as the broilers. In broiler chicken embryos immunized in ovo, only strain IBDV 2512 induced antibody production, and such chickens were protected against IBD at 3 weeks of age. The complex vaccine administered in ovo has been used successfully at farm hatcheries as well.
Authors:Sana Al-Shaikh, Abiola Senok, Abdulrahman Ismaeel, and G. Botta
The association between putative virulence genes in
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
invasiveness. We studied eight
strains isolated from patients whose clinical data were scored to determine severity of infection. Cytolethal distending toxin
, invasion associated marker
and Campylobacter invasion antigen
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
strains were more invasive than the
strains. One of the
strains showed invasion levels similar to
strains, but the second strain had a non-invasive phenotype. The findings indicate a correlation between
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.
Authors:Angela Lacombe-Antoneli, S. Píriz, and S. Vadillo
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).
Authors:Ágnes Szabó, Zoltán Sipák, András Miczák, and Ildikó Faludi
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.
Authors:G. Kulcsár, P. Soós, L. Kucsera, R. Glávits, and V. Pálfi
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.
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
). 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.
Authors:L. Makrai, K. Kira, A. Kono, Y. Sasaki, T. Kakuda, S. Tsubaki, L. Fodor, J. Varga, and S. Takai
virulence plasmids in the isolates from infected foals, dog and monkey. Onderstepoort J. Vet. Res. 68 ,105-110.
Prevalence of virulent Rhodococcus equi in isolates from soil collected from 2 horse farms in South Africa and