Abstract
Chickens can be infected with Salmonella enterica at any time during their life. However, infections within the first hours and days of their life are epidemiologically the most important, as newly hatched chickens are highly sensitive to Salmonella infection. Salmonella is initially recognized in the chicken caecum by TLR receptors and this recognition is followed by induction of chemokines, cytokines and many effector genes. This results in infiltration of heterophils, macrophages, B- and T-lymphocytes and changes in total gene expression in the caecal lamina propria. The highest induction in expression is observed for matrix metalloproteinase 7 (MMP7). Expression of this gene is increased in the chicken caecum over 4000 fold during the first 10 days after the infection of newly hatched chickens. Additional highly inducible genes in the caecum following S. Enteritidis infection include immune responsive gene 1 (IRG1), serum amyloid A (SAA), extracellular fatty acid binding protein (ExFABP), serine protease inhibitor (SERPINB10), trappin 6-like (TRAP6), calprotectin (MRP126), mitochondrial ES1 protein homolog (ES1), interferon-induced protein with tetratricopeptide repeats 5 (IFIT5), avidin (AVD) and transglutaminase 4 (TGM4). The induction of expression of these proteins exceeds a factor of 50. Similar induction rates are also observed for chemokines and cytokines such as IL1β, IL6, IL8, IL17, IL18, IL22, IFNγ, AH221 or iNOS. Once the infection is under control, which happens approx. 2 weeks after infection, expression of IgY and IgA increases to facilitate Salmonella elimination from the gut lumen. This review outlines the function of individual proteins expressed in chickens after infection with non-typhoid Salmonella serovars.
Highlights
Chickens can be infected with Salmonella enterica at any time during their life
Additional fimbrial operons found in other Salmonella serovars [8] or single nucleotide polymorphisms found within the same fimbrial genes present in different serovars [9] may further affect their adhesion to the chicken gut epithelium
We recently described that the caecum has a “buffering” capacity, i.e. the expression of genes involved in normal gut function is preserved even during minor inflammatory response
Summary
Events in the chicken caecum following infection of young chickens with non-typhoid serovars can be summarised as follows. IFIT5, LYG2 and MMP7 are induced, with IFIT5 and MMP7 being expressed by cells of non-leukocyte origin, i.e. this response is independent of infiltrating leukocytes. Maximal expression of these genes is achieved within 48 hours post-infection of newly hatched chickens with S. As summarised in the previous paragraph, Salmonella can induce an inflammatory response in the caecum of newly hatched chickens, but the resistance of chickens older than one month is quite high. All of these questions can nowadays be relatively addressed using new instruments in the area of mass spectrometry and/or NextGen sequencing All of this guarantees that the interaction between Salmonella and chickens will remain an attractive model for future studies.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
