Abstract: The preliminary investigation is to explore whether SPF chicken are infected by avian Chlamydophila psittaci (C.psittaci), then whether the associated avian vaccines contaminated with C.psittaci. In current study，70 serums from different ages of SPF chicken were collected to detect the antibody against C.psittaci using commercial indirect haemagglutination(IHA) test and immunofluorescence assay (IFA). Meanwhile, 30 egg yolk membranes were chosen for detecting the antigen presence by IMAGENTM Chlamydia kits.Moreover，41 batches of vaccines originated from SPF eggs were collected from local distributors in four provinces and chlamydial contamination was confirmed by IFA test kits. The seropositivity was 31.4% (IFA) and 5.7% (IHA) in 70 serum samples，respectively. The positive of antigen was 33.3% in SPF eggs and 31.7% in chicken vaccines，respectively.The antigen was identified in the egg yolk membrane. The above evidences indicated that Chlamydophila psittaci was prevalent in SPF chicken and it was vertical transmit way from the yolk membranes of SPF eggs to offspring as well as contamination for chicken vaccines. It is urgent to take some concreted measures to monitor the infection of Chlamydophila psittaci in SPF chicken.

Key words: Chlamydophila psittaci; antigen; antibody; vaccine; SPF chicken