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The Thai Journal of Veterinary Medicine

Abstract

This study was designed to investigate the pathogenesis of infectious bronchitis virus (IBV), a new variantgenotype and QX-like IBV, isolated in Thailand. Sixty, 28-day-old, female broiler chickens were divided into 3 groupsof 20 chickens each (groups 1-3) and sixty, 1-day-old, female broiler chickens were divided into 3 groups of 20chickens each (groups 4-6). The chickens in groups 2 and 5 were inoculated with QX-like IBV (isolate THA80151)whereas the chickens in groups 3 and 6 were inoculated with a new variant genotype IBV (isolate THA90151). Thechickens in groups 1 and 4 served as negative control groups. Clinical signs and mortality rates were observed for 14days post-inoculation (dpi). The chickens were weighed at 0, 7 and 14 dpi. At 7 and 14 dpi, five chickens per groupwere humanely killed. The tracheas and kidneys were collected for IBV detection and histopathological lesion scoreevaluation. The results revealed that at 7 dpi, the average body weight of the chickens in groups 2 and 6 wassignificantly lower than that of the negative control groups (groups 1 and 4, respectively) (p<0.05). Groups 2 and 5had one dead chicken in each (5% per group). As for the histopathological lesion score evaluation, lesion scores forthe trachea were not significantly different among infected groups (p>0.05) at 7 dpi but the score for group 5 wassignificantly higher than that for group 2 at 14 dpi (p<0.05). As for the kidneys, there was no significant difference inthe lesion score among the infected groups at both 7 and 14 dpi (p>0.05). This study indicates that both of the ThaiIBV isolates have an affinity to cause respiratory and kidney lesions and an effect on growth rate was found over 7dpi.

Publisher

Faculty of Veterinary Science, Chulalongkorn University

First Page

51

Last Page

57

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