Comparative Sensitivities of Oviduct and Tracheal Organ Cultures and Chicken Embryo Kidney Cell Cultures to Infectious Bronchitis Virus

In vitro studies with organ (oviduct and trachea) and chicken embryo kidney cell cultures were attempted to assess the pathogenicity of locally isolated infectious bronchitis virus (IBV-P:120) initially isolated from the oviduct of young chicks. In oviduct cultures infected with IBV, ciliary movements decreased as early as 24 hours postinoculation (PI), and on the 6th day ciliary movements ceased completely. Cytopathic changes were also noticed. Immunofluorescent antigen was detected from 1 to 6 days PI, the maximum being on the 3rd day. The characteristic microscopic changes in the oviduct explants were reduced by 24 hours PI and had completely ceased on the 5th day. Cytopathic effect and immunofluorescent antigen were present from 1 to 8 days PI, being maximum on the 5th day. Histological changes marked by loss of cilia, rounding of the epithelial cells, degeneration, and sloughing were detected from 2 to 8 days PI. Low-embryo-passaged (EP-7) IBV did not produce cytopathic effect on the chicken embryo kidney cell cultures. On the contrary, high-embryo-passaged (EP-14) virus produced cytopathic effect at the third tissue-culture-passage level.