Isolation of Chlamydophila psittaci from avian samples and establishment of a respiratory infection murine model

Abstract:

Abstract:[Objective] To optimize the isolation and culture technique of Chlamydophila psittaci avian strains and to establish an animal model infected with C. psittaci. [Methods] C. psittaci ompA gene was amplified from DNA extracted from bird livers by polymerase chain reactions (PCR). For the PCR positive avian samples, the liver tissues were homogenized and used to incubated with HeLa or Vero cell monolayers for 72 h in different dilutions，and chlamydia inclusion bodies were detected by immunofluorescence or Giemsa staining. Different dose of the avian strains(2×104, 2×105, 2×106 IFUs) were used to attack C57BL/6 mice by intranasal injection，mice were sacrificed on day 5 or day 10 after infection, and the histopathology changes were analyzed by H&E and immunohistochemistry staining in different organs. [Results] Six of one hundred avian samples were positive by C.psittaci ompA gene amplification, and three were positive by cell culture. The C.psittaci avian strains were cultured in Vero or HeLa cells. Vero cells showed stronger tolerance of cytolysis after chlamydia infection and chlamydia inclusion bodies were larger and more dense. Successfully establish a murine model of intranasal infection with C.psittaci, and 2×105 IFU is the suitable amount of organisms to induce respiratory chlamydia infection．[Conclusion] The isolation and culture condition was optimized for C.psittaci avian strains, and a murine model of respiratory tract infection by C.psittaci was successfully established, which can be applied to the clincal diagnosis of C.psittaci and epidemiological or pathogenetic study.