Study On Roles Of C3aR And C5aR In Chickens Infected With Cryptosporidium Baileyi

Cryptosporidium, a kind of important parasitic protozoa, can cause severe diarrhea in human and animal. Cryptosporidiosis is leaded by Cryptosporidium, also can be a serious damage to public health. For animals, cryptosporidium mainly result in respiratory and digestive diseases and followed by physical deterioration, even death, therewith great economic losses. Cryptosporidium baileyi is a species of Cryptosporidium which parasite in the respiratory tract of a variety of birds. For wild infection of chickens, the oocysts mainly parasite in larynx, trachea, bronchi, bursa of fabricius and cloacae, cause respiratory disease, affect the healthy development of the poultry industry. However, there is no drug or vaccine can effectively prevent or control cryptosporidiosis today. Some studies found that the adaptive immunity, especially CD4+ T cell immune, the key to attack cryptosporidium, plays an important role in the infection and elimination of cryptosporidium. And there are variety of factors can exactly regulate the function of immunological effect. To illuminate the role of anaphylatoxin receptor during cryptosporidium infection, present study used chickens infected with C. baileyi as the infected model, and use quantitative real-time PCR and ELISA to investigate mRNA and protein expression of C3 aR and C5 aR in C. baileyi parasite sites(trachea, bursa of fabricius, cloacae) and spleen. Then we detected the oocysts shedding and the expression of related cytokines(IL- 17, IFN-γ, IL- 4, STAT3, STAT4 and STAT6) after using C3 aR and C5 aR antagonists respectively. The results are as follows:1. The mRNA and protein level of C3 aR in C. baileyi infection sites(trachea, bursa of fabricius and cloacal) and spleen dynamically raised exprssion. The C3 aR mRNA level in trachea, bursa of fabricius and cloacal elevated at 7d pi, 10 d pi and 16 d pi(P < 0.05), and the C3 aR mRNA level in spleen significantly increased at 7d pi and 16 d pi(P < 0.05). Protein level of C3 aR decreased(P < 0.05) during innate immunity, then subsequently increased, and peaked at 7d pi(P < 0.05), suggesting C3 aR has function in acquired immune.2. C5 aR mRNA and protein level dynamically raised expression in infection sites(trachea, bursa of fabricius and cloacal) and spleen. C5 aR mRNA level significantly increased at 7d pi and 28 d pi in detected samples(P < 0.05), and peaked at 28 d pi in the trachea, bursa of fabricius and spleen. In addition, C5 aR expression peaked at 10 d pi and 16 d pi in bursa of fabricius while 10 d pi in cloacal(P < 0.05), which the oocysts shedding also peaked at 10 d pi and 16 d pi coincidentally. The C5 aR protein level declined during the innate immune stage(24 h and 48 h) and raised gradually, peaked at 7d pi, which means C5 aR plays an important role in acquired immune phase.3. The mRNA expression of IL-17, IFN-γ, IL-4, STAT3, STAT4 and STAT6 dynamically decreased in infected sites(trachea, bursa of fabricius and cloacal) and the spleen.The dynamical change of C3 aR and C5 aR in chickens infected with C. baileyi suggested that C3 aR and C5 aR may participate in C. baileyi infection and clearing. After suppress both of them, the results of IL-17, IFN-γ, IL-4, STAT3, STAT6 and STAT4 detection predicte C3 aR and C5 aR were likely to contribute to C. baileyi eliminating by adjusting the change of these cytokines.