Tóth, I., Schmidt, H., Kardos, G., Lancz, Z., Creuzburg, K., Damjanova, I., Pászti, J., Beutin, L. and Nagy, B. (2009): Virulence genes and molecular typing of different groups of Escherichia coli O157 strains in cattle. Appl. Environ. Microbiol. 75
Authors:Ayat Moradipour, Afra Khosravi and Fatemeh Piri
continued process, the chronic gastritis is created. These conditions in different patients may lead to gastric atrophy, intestinal metaplasia, or gastric cancer, depending on virulence factors, host genetic factors and, as previously stated, the host immune
The virulence frequency of 750 wheat powdery mildew isolates of wheat genotypes, carrying 23 Pm-genes and gene combinations, was studied over ten consecutive years from 2004 to 2013. Seventy-eight previously known and 39 new pathotypes were identified during this period. The results indicate that the majority of Pm-genes have high level of virulence. Sixty to ninety percent of the isolates were virulent to Pm6, Pm8, Pm8+11, Pm2+4b+8, Pm3g, Pm10+15, Pm10+14+15. The virulence frequency was variable for Pm1a, Pm2, Pm3a, Pm3b, Pm3c, Pm5, Pm7 genes and reached high level in certain years. The virulence frequency to genes Pm20, Pm37, Pm4a+ and to gene combination with Pm3c+5a+35 and breeding lines CN240/06, CN98/06 and CN158/06 ranged from 1 to 8%. Bread wheat lines CN240/06, CN98/06 and CN158/06, derived from interspecific crosses, proved to be highly resistant to powdery mildew.
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.
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: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.