Key Points

Chicken alloantigen systems A and E are located on Galgal microchromosome 26.

Alloantigen A is C4BPM (complement component 4 binding protein, membrane).

Alloantigen E is FCAMR (Fc fragment of IgA and IgM receptor).

Abstract

The tightly linked A and E blood alloantigen systems are 2 of 13 blood systems identified in chickens. Reported herein are studies showing that the genes encoding A and E alloantigens map within or near to the chicken regulator of complement activation (RCA) gene cluster, a region syntenic with the human RCA. Genome-wide association studies, sequence analysis, and sequence-derived single-nucleotide polymorphism information for known A and/or E system alleles show that the most likely candidate gene for the A blood system is C4BPM gene (complement component 4 binding protein, membrane). Cosegregation of single-nucleotide polymorphism–defined C4BPM haplotypes and blood system A alleles defined by alloantisera provide a link between chicken blood system A and C4BPM. The best match for the E blood system is the avian equivalent of FCAMR (Fc fragment of IgA and IgM receptor). C4BPM is located within the chicken RCA on chicken microchromosome 26 and is separated from FCAMR by 89 kbp. The genetic variation observed at C4BPM and FCAMR could affect the chicken complement system and differentially guide immune responses to infectious diseases.

Footnotes

This work was supported by the National Institute of Food and Agriculture, the U.S. Department of Agriculture National Research Support Program-8 (NRSP-8) coordinators, Hy-Line International, and the West Virginia University Elwood and Ruth Briles Avian Alloantigen Research Fund.

Abbreviations used in this article:

C4BPAα-chain of the C4-binding proteinC4BPBβ-chain of the C4-binding proteinC4BPMcomplement component 4 binding protein, membraneCR1Lcomplement receptor 1–likeFCAMRFc fragment of IgA and IgM receptorGOGene OntologyGWASgenome-wide association studyNCBINational Center for Biotechnology InformationNIUNorthern Illinois UniversityRCAregulator of complement activationRIRRhode Island RedSNPsingle-nucleotide polymorphismUTRuntranslated regionWLWhite LeghornWPRWhite Plymouth RockReceived October 20, 2021.Accepted July 7, 2022.Copyright © 2022 by The American Association of Immunologists, Inc.