Research Understanding the role of immune responses to Chlamydia abortus in sheep Chlamydia abortus is the foremost cause of diagnosed abortion in sheep worldwide, referred to as ovine enzootic abortion (OEA) or enzootic abortion of ewes. The development of a safe and effective vaccine deployed alongside existing molecular diagnostic tests remains a long-term ambition to reduce impact of this disease. To help achieve this we require a greater understanding of the interaction between the sheep’s immune system and the Chlamydia bacterium to find out how the infection leads to disease and what are the key protective immune responses. T lymphocytes are known to play an important role in this context and these cells release soluble factors known as cytokines to help direct the immune response. A key cytokine involved in the host response to Chlamydia abortus is interferon gamma (IFNɣ) that is known to play a role in controlling the intra-cellular growth of the pathogen. Relatively little is known about the other cytokine proteins released by the host that may contribute to disease outcomes (abortion or birth of live lambs). The pattern of cytokine proteins released were hypothesised to affect the outcome of pregnancy following infection with C. abortus. Moredun scientist, Sean Wattegedera, spent some time researching this subject and put together a body of work involving
Dr Sean Wattegedera.
six original research publications recently submitted to the University of Edinburgh for the award of a PhD. Sean developed several new immunological assays for use in sheep to help identify and characterise different T-cell populations that have distinct immunological functions involving activation and down regulation of host responses. Analysis of placental tissues and associated lymph nodes revealed a specific set of cells and molecules present, that are unique to all placental
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Moredun Magazine | Autumn/Winter 2021
mammals studied to date that affects pregnancy success and infection control. Analysis of proteins secreted from cultured T lymphocytes revealed patterns of Chlamydiaspecific cytokine production during infection with C. abortus, with selective elevation of the cytokines (IFNɣ) and IL-10 during latent and active disease. Several new areas of investigation have been identified that should accelerate
innovative research in reproductive disease vaccinology. Understanding the key protective immune responses and how they are induced, will aid the design of new vaccines to protect against OEA and indeed may pave the way for much sought after multi-pathogen vaccines against reproductive diseases of small ruminants. Congratulations to Sean on achieving his PhD.
