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Document Type

Thesis - University Access Only

Award Date

2015

Degree Name

Master of Science (MS)

Department / School

Animal Science

First Advisor

Michael G. Gonda

Abstract

Humoral vaccine response has been shown to be important for disease protection. However, heritability estimates for Escherichia coli (E. coli) O157:H7 vaccine response in beef cattle have not been estimated, and individual SNPs associated with an E. coli O157:H7 vaccine response in beef cattle have not been identified. Our objective was to estimate the heritability and identify SNP in association with humoral response to a commercially available E. coli 0157:H7 vaccine. Calves were part of the USMARC Germplasm Evaluation herd, which consists of various proportions of 16 different breeds. Calves (n=642) were administered a commercially available Escherichia coli (E. Coli) O157:H7 vaccine (Epitopix, Willmar, MN) at 74 to 171 days old (d0) and a booster vaccination three weeks later (d21). Three blood samples were collected: 1) time of initial vaccination (d0), 2) time of booster vaccination (d21), and 3) approximately one month following booster vaccination (d56). Antibodies present in plasma that were specific for the siderophore receptor and porin (SRP) proteins used in the vaccine were measured with an enzyme-linked immunosorbent assay (ELISA) in parallel with positive and negative controls. Sampleto- positive (S/P) ratios were calculated from ELISA optical densities for each sample. Calves were genotyped with the Bovine HD GGP chip. Vaccine response was defined as the difference between 1) antibodies present at time of booster shot minus antibodies ! ! xi! present at time of initial vaccination (initial response), 2) antibodies present one month after booster vaccination minus antibodies present at time of booster vaccination (booster response), and 3) antibodies present one month after booster vaccination minus antibodies present at time of initial vaccination (overall response). The estimated heritability of initial response to the vaccine was equal to 0.29 in the iterative MIVQUE genomic model with contemporary group as a fixed effect and calf age as a covariate. Initial heritability was 0.08 using the MTDFREML pedigree model with fixed effects of birth location and gender and covariates of heterosis and calf age. However, we did not find evidence that the booster or overall response to the vaccine was heritable in either model. We conclude that the initial humoral response to this E. coli 0157:H7 vaccine was heritable. For the genome wide association study (GWAS), initial response (d21-d0) was used to identify SNPs associated with vaccine response. A linear model with fixed effects sex, birth location, and genotype and covariates heterosis and calf age at initial vaccination was used. At the 5% genome wide significance level, two SNP were significantly associated with vaccine response: BTA4; rs109387213 with additive effect 0.23 ± 0.040 and dominance effect 0.19 ± 0.043, and BTA10; rs109587322 with additive effect 0.00 ± 0.013 and dominance effect -0.08 ± 0.016. At the 5% false discovery rate (FDR), one additional SNP was significantly associated with vaccine response (BTA19; rs109191037 with additive effect 0.03 ± 0.011 and dominance effect 0.05 ± 0.014).

Library of Congress Subject Headings

Beef cattle--Virus diseases--Vaccination
Escherichia coli O157:H7
Foodborne diseases--Prevention

Description

Includes bibliographical references (pages 60-61)

Format

application/pdf

Number of Pages

76

Publisher

South Dakota State University

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Rights Statement

In Copyright