Molecular identification and characterization of a novel chicken leukocyte immunoglobulin-like receptor A5

Authors: TRUONG, AD - National Institute Of Veterinary Research; HONG, Y - Chung-Ang University; NGUYEN, HT - Chung-Ang University; NGUYEN, CT - National Institute Of Veterinary Research; CHU, NT - National Institute Of Veterinary Research; TRAN, HTT - National Institute Of Veterinary Research; DANG, HV - National Institute Of Veterinary Research; Lillehoj, Hyun; HONG, YH - Chung-Ang University

Submitted to: British Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/1/2020
Publication Date: 9/25/2020
Citation: Truong, A., Hong, Y., Nguyen, H., Nguyen, C., Chu, N., Tran, H., Dang, H., Lillehoj, H.S., Hong, Y. 2020. Molecular identification and characterization of a novel chicken leukocyte immunoglobulin-like receptor A5. British Poultry Science. https://doi.org/10.1080/00071668.2020.1812524.
DOI: https://doi.org/10.1080/00071668.2020.1812524

Interpretive Summary: Limited information on chicken immune system and immune molecules hinders progress in understanding host-pathogen interaction and vaccine development in poultry. In this paper, ARS scientists collaborated with scientists in Korea to investigate the leukocyte immunoglobulin-like receptor (LILR) family since they regulate immune responses in chickens. LILR proteins exert both stimulatory or inhibitory function and they are expressed on diverse cells of immune system. In the present study, novel chicken gene called ILRA5 was cloned and its variants, namely LILRA5R and LILRA5S, were isolated from macrophage (HD11) cell line. The results showed that LILRA5 is a key molecule that regulates the immune system although LILRA5 gene has not been characterized in avian species, including chickens until this work. Furthermore, LILRA5 from chicken lines 6.3 and 7.2, two different chicken lines showing different disease susceptibility to many infectious diseases of poultry, is associated with phosphorylation of Src kinases and SHP2, which play a regulatory role in immune functions. These data suggested that LILRA5 encodes innate immune receptors essential for macrophage immune response and its understanding provides novel insights into the regulation of immunity and immunopathology. Deeper understanding of the intracellular signal transduction pathways initiated by proteins of LILRA5 genes will enhance our understanding of chicken immune system and our ability to manipulate its activation to enhance host response to pathogens.

Technical Abstract: Leukocyte immunoglobulin-like receptor A5 (LILRA5) is a key molecule that regulates the immune system. However, LILRA5 gene has not been characterized in avian species, including chickens. The present study aimed to identify and functionally characterize LILRA5 identified from two genetically disparate chicken lines, viz., Marek's disease (MD)-resistant (R) line 6.3 and MD-susceptible (S) line 7.2. Multiple sequence alignment and phylogenetic analysis further confirmed that the identity and similarity homologies of amino acids of LILRA5 in the chicken line 6.3 and 7.2 ranged between 93% -93.7%, whereas those between chicken and mammal ranged between 20.9% -43.7% and 21.1% -43.9%, respectively. The newly cloned chicken LILRA5 from chicken lines 6.3 and 7.2 revealed high conservation and a close relationship with other known LILRA5 mammalian proteins. Our finding indicated that LILRA5 from chicken lines 6.3 and 7.2 is associated with phosphorylation of Src kinases and SHP2, which play a regulatory role in immune functions. Moreover, our results demonstrated that LILRA5 in chicken lines 6.3 and 7.2 is associated with the activation of major histocompatibility complex (MHC) class I and ß2-microglobulin and induces the expression of the transporter associated with antigen processing. In addition, LILRA5 in both chicken lines activates and induces Janus kinase (JAK) -signal transducer and activator of transcription (STAT), nuclear factor kappa B (NF-'B), phosphoinositide-3-kinase (PI3K)/protein kinase B (AKT), and extracellular signal-regulated kinase (ERK)1/2 signaling pathways; Toll-like receptors; and Th1-, Th2-, and Th17- cytokines. These data suggested that LILRA5 has innate immune receptors essential for macrophage immune response and provide novel insights into the regulation of immunity and immunopathology.