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Title: INTERLEUKIN-8 HAPLOTYPE STRUCTURE FROM NUCLEOTIDE SEQUENCE VARIATION IN COMMERCIAL POPULATIONS OF U.S. BEEF CATTLE

Author
item Heaton, Michael - Mike
item Chitko-Mckown, Carol
item GROSSE, WILLIAM - FORMER ARS EMPLOYEE
item Keele, John
item Keen, James
item Laegreid, William

Submitted to: Mammalian Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2000
Publication Date: 3/1/2001
Citation: Heaton, M.P., Chitko Mckown, C.G., Grosse, W.M., Keele, J.W., Keen, J.E., Laegreid, W.W. 2001. Interleukin-8 haplotype structure from nucleotide sequence variation in commercial populations of U.S. beef cattle. Mammalian Genome. 12:219-226.

Interpretive Summary: Infectious diseases in cattle are a significant source of economic loss and represent a potential risk to human health. Improvements in herd health and food safety may result if individuals with the highest risk for infectious disease are eliminated from the production cycle. Our goal is to utilize an animal's DNA sequence information to estimate its risk of acquiring or maintaining infections. The present research accomplished two necessary aims: first, to create a panel of 96 sires that reflects the breadth of genetic diversity in U.S. beef cattle, and second, to characterize genetic variation of interleukin (IL)-8 DNA segments in commercial populations. IL8 encodes a proinflammatory cytokine that attracts and activates neutrophils in the early stages of host defense against bacterial invasion. The latter aim is a requisite for epidemiological studies designed to test whether IL8 alleles are risk factors for acquiring or maintaining bacterial linfections in production environments.

Technical Abstract: The aim of the present study was twofold: to design a panel of 96 sires that reflects the breadth of genetic diversity in U.S. beef cattle, and second, to use this panel to discover necleotide sequence diversity and haplotype structures of interleukin (IL)-8 in commercial populations. The latter is a requisite for epidemiological studies designed to test whether IL8 alleles are risk factors for acquiring or maintaining bacterial infections in production environments. IL-8 encodes a proinflammatory cytokine that plays a central role in cell-mediated immunity by attracting and activating neutrophils in the early stages of host defense against bacterial invasion. Seven single-nucleotide polymorphism (SNP) markers were identified by sequencing 2 IL8 DNA segments amplified from the panel of 17 popular cattle breeds (MARC beef cattle diversity panel, version 2.1). Assays for automated genotype scoring by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) were developed to independently verify the 7 SNP alleles in the 96 bulls and 313 cattle from the MARC reference population. Five haplotype structures, spanning the 2 IL8 DNA segments, were unambiguously defined for the set of 7 IL8 SNPs. From the breadth of germplasm in bovine diversity panel, the 5 haplotype structures for IL8 are estimated to represent >98% of those present in these DNA segments in commercial populations of U.S. beef cattle. The frequencies of the 5 respective haplotypes in the 8 Angus sires of the diversity panel (0.75, 0.25, 0.00, 0.00, 0.00) were similar to those scored in 150 purebred Angus cattle from 6 herds in 4 Midwestern states (0.82, 0.18, 0.01, 0.00, 0.00), suggesting that the diversity panel may also be useful for estimating allele frequencies in commercial populations.