Determining chicken immunoglobulin-like receptors (CHIRs) expression and their effect on immune response in a macrophage disease model

Abstract Immunoglobulin-like receptors are large transmembrane glycoproteins who direct the balance of the immune response. However, the full repertoire and effect of putatively activating, inhibiting, or dually working CHicken Immunoglobulin-like Receptors (CHIR-A, -B, and -AB, respectively) on immune responses in chickens, are not well understood. The objective was to characterize CHIRs expression and role in immune responses in the B-type homozygous chicken. B2B2 and B19B19 chicken lines were selected as model for their remarkable differences in disease susceptibility to coronavirus and other viral infections associated with the selectively bred major-histocompatibility complex class I (MHC-I), B locus. We first identified CHIRs from the new GRCg7b genome assembly by amino acids charge and protein motifs of CHIR -A, -B, or -AB. Subsequently, the transcriptomes of IFN-stimulated monocyte-derived macrophages from B2B2 or B19B19 were analyzed for CHIR abundance and ratio of CHIR-A:CHIR-B expression. Also, pooled siRNAs targeting CHIR-AB and or CHIR-B were generated for application in a monocyte-derived macrophage and T cell co-culture model. A higher median expression of CHIR-A in comparison to CHIR-B transcripts was observed in the B2B2 obtained macrophages; and inversely so for the B19B19 genotype 48-hours post-stimulation. Too, preliminary work show that CHIR-Bi enhances macrophage-mediated anti-viral response, endorsing CHIR-Bs suppressive role. These characterizations align with disease susceptibility traits of the B19B19 chicken line such that they link MHC and CHIRs, and highlight CHIRs in active infection and immunity.