Abstract:
Nematodes of the genus Ascaridia are known to infect many species of birds and result in fatal diseases. A. galli
damages the intestinal mucosa of chickens leading to blood loss, secondary infection and occasionally the obstruction
of small intestines due to high worm burden. This study investigated the gene expression profiles in
chickens from two different provinces of South Africa naturally exposed to A. galli infestations and tested either
positive or negative for the parasite. The study further investigated gene expression profiles of the A. galli
infected duodenum, jejunum and ileum tissues of the small intestines. The A. galli positive intestines displayed
hypertrophy of the intestinal villi with accumulation of inflammatory cells and necrosis of the crypts of
Lieberkühn glands, lesions that were absent in the uninfected intestines. Total RNA isolated from small intestines
of infected and non-infected intestines was sequenced using Illumina HiSeq technology to generate up to
23,856,130 reads. Between any two-way comparisons of the intestines, 277 and 190 transcripts were significantly
expressed in Limpopo and KwaZulu-Natal (KZN) chickens, respectively. Gene ontology analysis of the
differentially expressed genes (DEGs) revealed an enrichment of genes reported to function in the immune
response, defense response, inflammatory response and cell signalling genes. T cell receptor signalling pathways
and arachidonic acid metabolism pathways were among the most significantly impacted pathways. Overall, the
study provided insights into adaptative mechanisms for chickens extensively raised in parasite infected environments.
