Molecular Characterization of Virulence Genes of Chlamydophila Psittaci Isolated From Avian Sources and its Importance

Abstract

Background: C. psittacci is one of the most prevalent infections in aviculture and represents the most important animal chlamydiosis of zoonotic character. Purpose: To determine the most proper diagnostic tool for C. psittaci via comparing between different methods applied on this study, in addition to the molecular characterization of chlamydia psittaci isolates. Methodology: 233 serum samples, 330 fecal swabs and 736 internal organs (liver, lung, heart and spleen) were obtained from ducks, ostriches, quail and pigeons. Sixty four tracheal swabs were obtained fron ostrich. C. psittaci was isolated from the samples by Chicken embryo inoculation via yolk sac method. Impression smears were made from the collected yolk sac membranes, stained with Gimenez stain and examined under an oil immersion to detect the presence of chlamydial inclusions. Immunoperoxidase test was used for detection of C. psittaci inclusion bodies in the yolk sac impression smears. Complement fixation test was used for detection of antibodies in the serum samples. Then molecular characterization of chromosomal DNA of C. psittaci was performed by PCR. Results: Positive samples of isolation showed dwarfed and congested embryos with congestion of their yolk sac vessels. Immuno-peroxidase stain positive slides showed discrete, densely labeled brown inclusion bodies was seen with in transparent background. The PCR results of chlamydia psittaci isolates showed that, in fecal samples, ostrich species had positive percentage for chlamydia psittaci (91.7 %), pigeon (86.7 %), quail (85.7 %), duck (80 %). In the tracheal swabs, ostrich species were positive for chlamydia psittaci (83.3 %). Samples of each studied species were positive for the presence of 16S rRNA gene of chlamydia psittaci, and, out of 16 samples, 16 (100%) was positive for ompA. Serodiagnosis by Complement fixation test showed that, out of 233 samples, 93 (40%) samples were positive for chlamydia psittaci. The results reveal that 57 (70.4%), 62 (76.5%), 35 (43.2%), 46 (56.8%), and 35 (43.2%) of the examined samples were positive for chlamydiosis using CFT, Giemsa stain, Gime´nez stain, IP and CFT respectively among 81 ducks. The positive results were 55 (70.5%), 26 (57.7%), 54 (35.9%), 55 (68.6%) and 30 (38.5%) respectively for the previous tests among 78 pigeons. Among 74 quail samples examined, positive