Ovine respiratory disease (ORD) is one of the chief causes of morbidity and mortality in sheep and lambs. It is multifactorial with both environmental stressors and co-infections predisposing the sheep to long-term chronic or acute inflammatory bacterial lung infections. The vaccines introduced over 35 years ago reduced the incidence and severity, but unacceptably high levels of ORD remain. To address ORD with modern, innovative solutions we first need to establish the basics. We will determine the microbiota of diseased compared to healthy lungs using 16S rRNA gene amplicon nanopore sequencing (MinION). Analysis pipelines are already in place to transform the data into information on the bacterial species/genus present and estimate the relative abundance. PCR and sequencing will further define species, strains, and serotypes. The presence of co-infections will be assessed through PCR and serology.
This work will show whether the current vaccines used for sheep pneumonia target the correct pathogens. The use of well-suited lung samples stored in a biobank from previous projects will allow work to begin immediately, whilst prospective collection of samples and associated metadata will increase the range of clinical presentations to be assessed. This will allow interrogation of any difference, for example, by signalment, pathological presentation, or management systems.
Sheep farmers will work in partnership with researchers throughout the project to place the scientific findings into context on their farms. Facilitated qualitative interviews will allow description of current practice and barriers to action. This partnership will allow co-development of practical interventions which will be disseminated to the wider farming and veterinary community.
This study will build contextualised understanding of the disease to underpin and define the next steps towards improved ORD control, thus reducing the losses experienced within the UK sheep industry.
Outcomes:
We assessed the types of bacteria present in the lungs of sheep with healthy lungs compared to sheep with lung disease. We showed that Proteobacteria and Firmicutes were the most highly abundant phyla for all samples but were more abundant in diseased than healthy ovine lung. The data suggested that there was a greater diversity of bacterial phyla in lesion tissue compared to healthy tissue although the difference was not statistically significant. Lungs from sheep which had pneumonia were associated with higher amounts of Clostridium genera compared to sheep which presented with other types of lung disease.
Our findings provide valuable insights into the microbial composition of the sheep lung and identify potential bacterial taxa associated with ORD, paving the way for further research into the pathogenesis and management of this disease.
Of particular interest, Clostridium genera were shown to be associated with pneumonia. This warrants further investigation as to how clostridial vaccines might impact respiratory disease in sheep.
Contact details:
Dr Chris Cousens
Senior Research Scientists
Moredun Research Institute