Molecular and virulence characteristics of an outer membrane-associated RTX exoprotein in Pasteurella pneumotropica

<p>Abstract</p> <p>Background</p> <p><it>Pasteurella pneumotropica </it>is a ubiquitous bacterium that is frequently isolated from laboratory rodents and causes various clinical symptoms in immunodeficient animals. Currently two RTX toxins, PnxIA and PnxIIA, which are similar to hemolysin-like high-molecular-weight exoproteins are known in this species. In this study, we identified and analyzed a further RTX toxin named PnxIIIA and the corresponding type I secretion system.</p> <p>Results</p> <p>The RTX exoprotein, PnxIIIA, contains only a few copies of the RTX repeat-like sequence and 3 large repeat sequences that are partially similar to the outer membrane protein found in several prokaryotes. Recombinant PnxIIIA protein (rPnxIIIA) was cytotoxic toward J774A.1 mouse macrophage cells, whereas cytotoxicity was attenuated by the addition of anti-CD11a monoclonal antibody. rPnxIIIA could bind to extracellular matrices (ECMs) and cause hemagglutination of sheep erythrocytes. Binding was dependent on the 3 large repeat sequences in PnxIIIA. Protein interaction analyses indicated that PnxIIIA is mainly localized in the outer membrane of <it>P. pneumotropica </it>ATCC 35149 in a self-assembled oligomeric form. PnxIIIA is less cytotoxic to J774A.1 cells than PnxIA and PnxIIA.</p> <p>Conclusions</p> <p>The results implicate that PnxIIIA is located on the cell surface and participates in adhesion to ECMs and enhanced hemagglutination in the rodent pathogen <it>P. pneumotropica</it>.</p

Prevalence and analysis of Pseudomonas aeruginosa in chinchillas

<p>Abstract</p> <p>Background</p> <p>Chinchillas (<it>Chinchilla laniger</it>) are popular as pets and are often used as laboratory animals for various studies. <it>Pseudomonas aeruginosa </it>is a major infectious agent that causes otitis media, pneumonia, septicaemia enteritis, and sudden death in chinchillas. This bacterium is also a leading cause of nosocomial infections in humans. To prevent propagation of <it>P. aeruginosa </it>infection among humans and animals, detailed characteristics of the isolates, including antibiotic susceptibility and genetic features, are needed. In this study, we surveyed <it>P. aeruginosa </it>distribution in chinchillas bred as pets or laboratory animals. We also characterized the isolates from these chinchillas by testing for antibiotic susceptibility and by gene analysis.</p> <p>Results</p> <p><it>P. aeruginosa </it>was isolated from 41.8% of the 67 chinchillas included in the study. Slide agglutination and pulsed-field gel electrophoresis discriminated 5 serotypes and 7 unique patterns, respectively. For the antibiotic susceptibility test, 40.9% of isolates were susceptible to gentamicin, 77.3% to ciprofloxacin, 77.3% to imipenem, and 72.7% to ceftazidime. DNA analyses confirmed that none of the isolates contained the gene encoding extended-spectrum β-lactamases; however, 2 of the total 23 isolates were found to have a gene similar to the <it>pilL </it>gene that has been identified in the pathogenicity island of a clinical isolate of <it>P. aeruginosa</it>.</p> <p>Conclusions</p> <p><it>P. aeruginosa </it>is widely spread in chinchillas, including strains with reduced susceptibility to the antibiotics and highly virulent strains. The periodic monitoring should be performed to help prevent the propagation of this pathogen and reduce the risk of infection from chinchillas to humans.</p

Study of stress in dairy cattle during student practical training on a farm

We investigated changes in cortisol (COR) concentration, which is well known as an index of stress in the serum of dairy cattle. The COR concentrations in serum obtained from dairy cattle were collected during practical training of first-year students on a farm attached to the Nippon Veterinary and Life Science University. Mean COR concentration in serum determined after practical training was significantly higher (P < 0.001) than that in serum collected before training. Discriminant analysis was used to classify the relation between COR concentration of serum collected before and after practical training. In conclusion, the data was bipartite according to the percentage of rise (rise rate) of COR concentration. Although the percentage of the rise was more than 300% in the high-rise-rate group, there was a significant negative correlation (P < 0.05) between age and COR concertation. It was thought that the high-rise-rate group has a chance to decrease stress after more experience. In contrast, the low-rise-rate group included 3 cattle indicating high COR concentration before and after practical training. Those 3 cattle were thought to be stressed easily. It is suggested that there was individual difference to stress