Research Of Cytokines Related With Innate Immunity And Parasite Load In Chickens Infected With NRTUAs

Chicken and eggs are one of the main routes of nutrient intake and their food safety cannot be ignored.As an important intermediate host for Toxoplasma gondii,chickens are closely associated with the quality and yield of meat and egg.Nonreplicating Toxoplasma uracil auxotrophs(NRTUAs)are non-replicating and highly attenuated strain of Toxoplasma gondii,which have the advantages of improving the immune microenvironment and modulating the immune response,and are expected to be used as an anti-Toxoplasma vaccine in poultry.In order to further investigate the differences in the tissue and organ changes of NRTUAs and RH strains in chickens and their effects on immune regulation in the spleen,this study was conducted to observe the clinical symptoms and histological changes in chickens by subcutaneous infection of the chicken’s neck.The observation was shown that the chickens in each group had normal gait,were full of energy,had good dietary status,and did not show any clinical disease,and no chickens were died.The histopathological results was shown that only the lungs of the RH group had pathological changes,while other tissues and organs were consistent with those of the NRTUAs and PBS groups,and no obvious pathological changes were found.The real-time fluorescence quantification of Toxoplasma gondii B1 gene in the chicken’s tissues and organs was able to determine the parasite load indirectly,as well as the infection status of each tissue and organ of the chickens.The results was shown that the load of NRTUAs in the tissues and organs of chickens was decreasing,and RH strain could colonize and develop in the tissues and organs of chickens,and the parasite load showed an increasing trend,indicating that NRTUAs would be gradually cleared by chickens as time gone by infection.Differences in the expression levels of relevant innate immune cytokines were detected by quantitative analysis for chicken spleens stimulated with NRTUAs or RH strains on days 2 and4.The results showed that the spleens stimulated with NRTUAs at DPI2 and DPI4 did not significantly up-or down-regulate the measured cytokines,while the spleens stimulated with RH strain at DPI2 and DPI4 significantly up-or down-regulated some of the immune-related factors.Hence,NRTUAs were non-pathogenic,which could stimulate a mild inflammatory response in chicken spleens and were gradually cleared by the host over time.This study provides a theoretical basis for the use of NRTUAs as an anti-Toxoplasma gondii vaccine in poultry.