Proteomic variations between a Mycoplasma gallisepticum vaccine strain and a virulent field isolate

Mollicutes (mycoplasmas) are pathogenic in a wide range of mammals (including humans), reptiles, fish, arthropods, and plants. Of the medically important mollicutes, Mycoplasma gallisepticum is of particular relevance to avian agriculture and veterinary science, causing chronic respiratory disease in poultry and turkey. Using two-dimensional electrophoresis based quantitative expression proteomics, the current study investigated the molecular mechanisms behind the phenotypic variability between a M. gallisepticum vaccine strain (6/85) and a competitive, virulent field strain (K5234), two strains which were indistinguishable using commonly accepted genetic methods of identification. Twenty-nine proteins showed a significant variation in abundance (fold change \u3e 1.5, p-value \u3c 0.01). Among others, the levels of putative virulence determinants were increased in the virulent K5234, while the levels of several proteins involved with pyruvate metabolism were decreased. It is hoped that the data generated will further the understanding of M. gallisepticum virulence determinants and mechanisms of infection, and that this may contribute to the optimization of diagnostic methodologies and control strategies

Understanding the Evolution of Emerging Bacterial Pathogens in Response to Host Resistance

Understanding the evolution of parasites and hosts following a host-shit event is increasingly recognised as being of great importance to public health and the clinical/veterinary sciences in predicting the behaviour and evolutionary consequences of emerging infectious diseases. Microbial pathogenesis and virulence are remarkably complex traits, and only by considering them in the context of their hosts can we begin to unravel key questions as to how and why disease emerges and persists. The period immediately following a host-shift event, where a pathogen circulating in one host species successfully jumps into another is critical – whether such outbreak events “burn out” or become endemic, and what the ramifications of this might be are difficult to model and predict. That microbial pathogens and their hosts are in a close coevolutionary relationship has been evident since the early days of our understanding of disease, but it is only relatively recently that the ecological, molecular, genomic and bioinformatic tools all required to understand the subject have become widely available and applicable. In the work presented within this thesis, we utilise an exceptionally well monitored and studied novel host-pathogen interaction – that of the avian bacterial pathogen Mycoplasma gallisepticum and its recently infected novel host the House Finch (Haemorhous mexicanus). Approximately 25 years ago this pathogen jumped from its established host in chickens into the wild passerine finch species, triggering an epidemic which has been well monitored from the outset We aim to address how host-pathogen coevolution drives particularly the evolution of microbial virulence. Our current understanding of such host-pathogen interactions within an evolutionary context centres around the mathematical and ecological framework of the “Trade-off hypothesis”, but many of the assumptions linking pathogen virulence, transmission and replication have been difficult to test or to integrate with our modern understanding of how microbial virulence is manifested on a molecular level. In exploring these issues throughout this text, we consider that this work has progressed our understanding in this field and goes some way towards this integration of evolutionary theory and more descriptive classical microbiology / molecular biology.Natural Environment Research Council (NERC

Molecular characterization and T and B cell epitopes prediction of Mycoplasma synoviae 53 strain VlhA hemagglutinin

Mycoplasma sinoviae is a major pathogen of poultry causing synovitis and respiratory infection. M. synoviae hemagglutinin (VlhA) is a lipoprotein encoded by related multigene families that appear to have arisen by horizontal gene transfer. It is an abundant immunodominant surface protein involved in host-parasite interaction mediating binding to host erythrocytes. Herein, we have performed in silico analysis of the vlhA gene product from the Mycoplasma synoviae 53 strain and compared it to the VlhA protein of M. synoviae WUV1853 strain. The VlhA of the M. synoviae 53 strain possesses 569 amino acids and showed 85% identity with the VlhA protein of the M. synoviae WUV1853 strain. Further, a signal peptide was identified from amino acid M1 to D28 and a cleavage site between D28 and Q29, both located in the N-terminal domain of the molecule. Additionally, an insertion of PAPT amino acids was observed between T30-P35 and a deletion of the amino acids GTPGNP within the PRR region of the VlhA from the M. synoviae 53 strain, which may be related to its reduced virulence. Finally, we have identified 17 B cell epitopes and 22 T cells epitopes within the VlhA from the M. synoviae 53 strain. The B cell epitope S263-D277 and the T cell epitopes N45-N54 and G58-N67 showed 100% and 87-100% identity, respectively, with regions of VlhA protein of tested Mycoplasma synoviae and Mycoplasma galisepticum strains. Thus, these peptides represent new candidate molecules for the development of efficient diagnostic assays and new subunit vaccines