Li Qiang
China Agricultural University, China
Title: Combination of inactivated EBs,chistosan and VCG induces a better protection against avian Chlamydia psittaci infection
Biography
Biography: Li Qiang
Abstract
Chlamydia psittaci is a global infection in poultry farms. Avian species get infected through Chlamydia-contaminated aerosol or food. Clinically, C. psittaci infection in chicken leads to the airsacculitis and severe pneumonia. Our recent reports indicated C. psittaci aggravates immune suppression and facilities secondary infection, i.e. avian influenza virus, ORT and E. coli. Its prevalence exacerbates poultry industry due to lack of commercial vaccine. An idea vaccine can be achieved by modifying the delivery vehicle, route of immunization or by using nanoparticles as vaccine adjuvants. In the current study, combination of chitosan hydrogel, Vibrio cholerae Ghost (VCG) and inactivated Chlamydia EBs induced strong antigen-specific humoral and cellular immune responses. Furthermore, it may generate strong protection, alleviate lesions in the respiratory tract and accelerates Chlamydia clearance. Chickens were immunized intransasally (IN) by the combination of 1´106 IFU of the purified inactivated EBs, VCG and chitosan hydrogel while birds were given intranasally with purified live EBs or UV-inactivated EBs or CPG and chitosan hydrogel as the control groups. Antibody levels, lymphocyte proliferations, cytokines in lung lavage fluids were measured using commercial kits. Finally, birds were challenged intra-tracheally with live EBs of Chlamydia psittaci HJ strain. Gross lesions, bacterial shedding and bacterial load in tissues were determined as described previously with some modifications. Regarding C. psittaci-specific antibodies via intranasal way or intramuscular inoculation, VCG+EBs+chitosan group induced a significant increase in comparison with the EBs vaccine or chitosan hydrogel group from day 7 to day 28. As for proliferative responses and CD4+ lymphocytes, the VCG+EBs+chitosan group was superior to the CPG+EBs+chitosan group. Moreover, VCG+EBs+chitosan group generated significantly higher IL-2, IL-12 and IFN-γ in lungs than those of CPG+EBs+chitosan group. Post challenge, significantly decreasing air sac lesions and bacterial shedding were found in the VCG+EBs+chitosan compared with the live EBs group or the UV-inactivated EBs group. A dose-dependent protection was found in the combination with 25-50 mg of VCG, chitosan and UV-activated EBs post challenge. In conclusion, chickens immunized with chitosan carrier capsulated inactivated EBs and VCG displayed not only high cellular immune responses, but also a robust humoral response against C. psittaci with a significant decreasing chlamydial loads.