Xin Fang

Document Type

Thesis - University Access Only

Award Date

2010

Degree Name

Master of Science (MS)

Department / School

Animal Science

Abstract

In a previous study, we concluded that the BVDV vaccine response may be heritable trait in cattle. However, no study has demonstrated which genes contribute to BVDV vaccine response. In this study, we hypothesized that two single nucleotide polymorphisms (SNPs) from the bovine leptin gene (leptin c.73 C>T) and complement receptor 2 gene (CR 2 c.3849 G>A) could affect the BVDV vaccine response. To test the effects of these two SNPs on the BVDV vaccine, 267 Angus and Angus-cross calves from three SDSU research herds were sampled. Humoral BVDV vaccine responses were measured from the blood samples of calves that were born between February and October, 2009. All calves were vaccinated with Pyramid 5 or 10 (Boehringer Ingelheim, Inc., St. Joseph, MO), which includes modified-live BVDV - 1 and BVDV - 2 strains. Plasma samples were collected at the time of vaccination ( d 0) for maternal BVDV antibody level measurements, testing for calves persistently infected (Pl) with BVDV and DNA extraction. Serum samples were collected at 22 to 29 days post-vaccination for BVDV antibody level measurements of vaccine response. No calf was detected as PI with BVDV by real-time RT-PCR for BVDV RNA from plasma. A BVDV antibody ELISA (ldexx, Inc., Westbrook, ME) was used to measure total BVDV-specific antibody from plasma and serum samples. Antibody concentrations were converted to sample-to positive (SIP) ratios, and SIP ratios at the time of vaccination (d 0) were subtracted from SIP ratios at the time of post-vaccination (d 22-29) to calculate vaccine response. Specific PCR-RFLP assays were designed for genotyping leptin and CR 2 polymorphisms. A linear model including effects of leptin or CR2 genotype, age of vaccination, gender, and herd was applied to estimate the effect of leptin and CR 2 polymorphisms on BVDV vaccine response. Herd and age of vaccination were significantly associated with vaccine response (p < 0.0001). Leptin, CR 2 genotype and gender were not significantly associated with BVDV vaccine response. However, CR 2 genotype was significantly associated with maternal antibody concentration at the time of vaccination ( p = 0.03 l) while leptin genotype tended to be associated with this trait ( p = 0.051 ). This study found no effect ofleptin c.73 C>T and CR 2 c.3849 G>A polymorphisms on BVDV vaccine response. However, further studies are needed to investigate the association between these SNPs and blood maternal BVDV antibody levels in calves.

Keywords: BVDV, leptin, CR 2, vaccine response, cattle

Library of Congress Subject Headings

Bovine viral diarrhea virus -- Vaccination
Cattle -- Genetics
Genetic polymorphisms
Leptin

Format

application/pdf

Number of Pages

97

Publisher

South Dakota State University

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