Poster Presentation International Veterinary Immunology Symposium 2016

O157:H7 Escherichia coli modulates rectal mucosal immune responses in cattle (#110)

Eric Cox 1 , Evelien Kieckens 1 , Joanna Rybarczyck 1 , Lieven Dezutter 1 , Daisy Vanrompay 2 , Robert W Li 3
  1. Fac. Vet. Med. - Ghent University, Merelbeke, BELGIUM, Belgium
  2. Laboratory of Immunology and Animal Biotechnology, Ghent University, Gent, Belgium
  3. Bovine Functional Genomics Laboratory, USDA-ARS, Beltsville, MD, USA

Enterohemorrhagic E. coli O157:H7 are frequently detected in bovine fecal samples at slaughter. Cattle do not show clinical signs upon infection, but for humans the consequences can be severe after consuming contaminated beef. The immune response against EHEC in cattle cannot always clear the infection as persistent colonization and shedding often occur in infected animals over a period of months. In previous infection trials, the primary immune response after infection was unable to protect cattle from re-infection. Furthermore, the duration of the primary infection was mostly shorter (<14days, n=32) than of the secondary infection (>28days, n=21). This might reflect suppression of immune pathways, making cattle more prone to persistent colonization after re-infection. Monitoring the antibody response against the type III secretion system proteins EspA and Esp B and Intimin in three 3-month-old calves infected t with E. coli O157:H7 and reinfected one week later showed indeed low serum IgG and IgA responses. Furthermore there were no rectal IgA responses. At euthanasia the bacterium could still be isolated from the rectum in all animals. Subsequently, RNA-sequencing (RNA-Seq) was used for transcriptome analysis of recto-anal junction tissue and ileal Peyer’s patches (IPP) in nine calves in response to a primary (n=3) and secondary infection (n=3). Non-infected calves served as controls (n=3). In tissue of the recto-anal junction, only 15 genes were found to be significantly affected by a first infection compared to 1159 genes in the IPP, whereas re-infection significantly changed the expression of 10 and 17 genes in the recto-anal junction and the IPP, respectively. The main effect on the transcriptome was immunosuppression due to an upregulation of immunosuppressive (7/12 genes) or a downregulation of immunostimulatory effects (69/94 genes) in the IPP. These data might indicate that a primary infection promotes a re-infection with EHEC by suppressing the immune function.