Messenger RNA expression of chicken CLOCK gene in the response to Campylobacter jejuni inoculation.

Campylobacter jejuni (C. jejuni) is a leading cause of human bacterial gastroenteritis worldwide. Previous research has shown that circadian rhythm plays a critical role in host response to C. jejuni colonization. The CLOCK gene is one of the core genes regulating circadian rhythms and shows significant expression on 7 d post-C. jejuni inoculation. The objective of this study was to investigate temporal and spatial expression of chicken CLOCK gene post-C. jejuni inoculation. Cecal and splenic RNA were isolated from 2 distinct chicken breeds and used to compare the mRNA expression of CLOCK gene between inoculated and noninoculated chickens within each breed and between breeds within each of inoculated and noninoculated groups. Our results showed that the CLOCK gene was significantly down-regulated at 20 h postinoculation (hpi) in cecum and spleen in Jiningbairi chicken. CLOCK gene was significantly down-regulated at 4 and 16 hpi and up-regulated at 8 hpi in cecum and spleen in specific pathogen free white leghorn noninoculated chicken. The findings suggested that expression of CLOCK gene was significantly changed post C. jejuin inoculation. This change was affected by genetic background, tissue, and time points postinoculation.