Apoptosis in experimentally infected chicks with avian infectious bronchitis

Apoptosis in experimentally infected chicks with avian infectious bronchitis

This experiment was performed to investigate apoptosis during undergoing pathogenesis of avian infectious bronchitis virus(IBV)-infected chicks. Sixteen days old chicks were infected with IBV, Massachusetts-41 strain(M-41, 10$^4$-10$^{5}$ EID$^{50}$ ) experimentally, they were autopsied to remove trachea, lung, kidney and cloacal bursa at 6hr, 12hr, 1 day, 3 day and 7 day post infection(PI) respectively for H-E and TUNEL staining. Grossly, mild serous, catarrhal exudate was observed in the trachea, nasal passages and sinuses nasal from 4 day PI. The cloacal bursa was swollen from 3 day PI. Histopathologically, the trachea was seen mild cellular infiltration, edema of the mucosa and submucosa, vascular congestion and mild hyperplasia of the epithelium from 6 hr PI and the changes were seen a little more severely on 7 day PI. It was observed that the cloacal bursa was getting more and more hyperplasia through the experiment. The nuclei degeneration were shown in the kidney on 7 day PI. No specific changes were seen in the lung. In TUNEL analysis, apoptotic cells showed sharp increasing at 12 hr PI and reaching a maximum on 1 day PI in the trachea, lung, kidney and cloacal bursa. And then apoptotic cells decreased gradually returning to a level of the control by 7 day PI in all the removed organs.