Proteomic identification of immunodominant membrane-related antigens in Campylobacter jejuni associated with sheep abortion

Applied Proteomics in 'One Health'

‘One Health’ summarises the idea that human health and animal health are interdependent and bound to the health of ecosystems. The purpose of proteomics methodologies and studies is to determine proteins present in samples of interest and to quantify changes in protein expression during pathological conditions. The objectives of this paper are to review the application of proteomics technologies within the One Health concept and to appraise their role in the elucidation of diseases and situations relevant to One Health. The paper develops in three sections. Proteomics Applications in Zoonotic Infections part discusses proteomics applications in zoonotic infections and explores the use of proteomics for studying pathogenetic pathways, transmission dynamics, diagnostic biomarkers and novel vaccines in prion, viral, bacterial, protozoan and metazoan zoonotic infections. Proteomics Applications in Antibiotic Resistance part discusses proteomics applications in mechanisms of resistance development and discovery of novel treatments for antibiotic resistance. Proteomics Applications in Food Safety part discusses the detection of allergens, exposure of adulteration, identification of pathogens and toxins, study of product traits and characterisation of proteins in food safety. Sensitive analysis of proteins, including low-abundant ones in complex biological samples, will be achieved in the future, thus enabling implementation of targeted proteomics in clinical settings, shedding light on biomarker research and promoting the One Health concept.

A Homologous Bacterin Protects Sheep against Abortion Induced by a Hypervirulent Campylobacter jejuni Clone

Campylobacter jejuni clone SA has emerged as the predominant cause of ovine abortion outbreaks in the United States (US). Despite the fact that commercial Campylobacter vaccines are available, their efficacy in protecting abortion induced by C. jejuni clone SA is uncertain, and a protective vaccine is needed to control the disease. In this study, an experimental homologous bacterin (made of a clone SA isolate) and two commercial Campylobacter vaccines were evaluated for their protection against C. jejuni clone SA-induced sheep abortion. All vaccines induced high levels of antibodies against C. jejuni clone SA in pregnant ewes, but only the experimental homologous bacterin produced significant protection (80%). Immunoblotting showed that the experimental vaccine elicited more specific antibodies against C. jejuni clone SA. These findings strongly suggest the necessity of developing a homologous vaccine for the control C. jejuni clone SA induced abortion on sheep farms.

Campylobacter-Associated Diseases in Animals

Campylobacter includes a group of genetically diverse species causing a range of diseases in animals and humans. The bacterium is frequently associated with two economically important and epidemiologically distinct reproductive diseases in ruminants: enzootic infectious infertility in cattle owing to Campylobacter fetus subsp. venerealis and abortions in sheep, goats, and cattle. Septic abortion, usually epizootic in sheep, has been historically associated with C. fetus subsp. fetus and to a lesser extent with Campylobacter jejuni. However, there has been a dramatic species shift in the etiology of Campylobacter abortions in recent years: C. jejuni has now replaced C. fetus subsp. fetus as the predominant cause of sheep abortion in the United States, which appears to be driven primarily by clonal expansion of a hypervirulent tetracycline-resistant C. jejuni clone. Here we provide a review on the recent advances in understanding the pathobiology of Campylobacter infections in animals, with an emphasis on the diseases in ruminants, covering epidemiology, pathogenesis, genomics, and control measures.

Seroprofiling at the Candida albicans protein species level unveils an accurate molecular discriminator for candidemia

Serum antibodies to specific Candida proteins have been reported as potential diagnostic biomarkers for candidemia. However, their diagnostic usefulness at the protein species level has hardly been examined. Using serological proteome analysis, we explored the IgG-antibody responses to Candida albicans protein species in candidemia and control patients. We found that 87 discrete protein species derived from 34 unique proteins were IgG-targets, although only 43 of them were differentially recognized by candidemia and control sera. An increase in the speciation of the immunome, connectivity and modularity of antigenic species co-recognition networks, and heterogeneity of antigenic species recognition patterns was associated with candidemia. IgG antibodies to certain discrete protein species were better predictors of candidemia than those to their corresponding proteins. A molecular discriminator delineated from the combined fingerprints of IgG antibodies to two distinct species of phosphoglycerate kinase and enolase accurately classified candidemia and control patients. These results provide new insight into the anti-Candida IgG-antibody response development in candidemia, and demonstrate that an immunoproteomic signature at the molecular level may be useful for its diagnosis. Our study further highlights the importance of defining pathogen-specific antigens at the chemical and molecular level for their potential application as immunodiagnostic reagents or even vaccine candidates.