Survey of tissue tropism and dissemination of ORT-R87-7/1387 strain of Ornithobacterium rhinotracheale in SPF chickens

Ornithobacteriosis is caused by Ornithobacterium rhinotracheale (ORT) that can cause economic losses to the poultry industry annually. The purpose of this study was to investigate tissue tropism and dissemination of ORT-R87-7/1387 strain of ORT in different organs of experimentally infected SPF chickens. Forty one-day-old SPF leghorn chicks were provided and divided randomly into two groups (20 chicks in the experimental and 20 chicks in the control group). They were kept in separate positive pressure isolators. At the age of three weeks، the chicks in the experimental group were inoculated intratracheally with 1× 1010 CFU of ORT. Each bird in control group was inoculated with PBS. The sample from trachea، lungs، liver and heart were collected at 2،4،6،8،10،12 and 14 days post-inoculation (PI). Three chickens of experimental group showed ruffled feathers from days 3 to 4 PI that this signs disappeared at 5 day PI. ORT was isolated in the trachea on days 2،4، 8 and 10 PI. The bacteria was also found in the lungs and liver on day 4 PI. But ORT was not detected in samples taken from heart during study. The results showed that this strain of ORT alone can not lead to mortality، severe clinical signs or gross lesions in infected chickens، but its replication in the trachea for a long time could render birds susceptible to other diseases.