1Graduated from School of Veterinary Medicine, Shiraz University, Shiraz, Iran
2Department of Clinical Sciences, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
3Department of Pathobiology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
This experimental study was carried out to induce a co-infection of H9 AIV and IBV with inoculums prepared from tracheal scrubbed epithelium tissues in natural co-infected birds to rule out the effect of field undesired environmental conditions and also other infectious causative agents. Eighty 1-day-old broilers were randomly divided into four equal groups. At 21 days of age, three test groups were inoculated intranasally with prepared inoculums containing IBV and H9 AIV alone and a co-infected group. The fourth group remained uninfected as a control group. The results showed that experimental co-infection of AIV and IBV increased the severity of clinical signs, mortality rate and gross lesions. The HI titer against AIV infection in the co-infected group was significantly higher than the HI titer of other groups, which may indicate that IBV could promote the propagation of H9N2 AIV or stimulate the immune response.