Document Type

Thesis - Open Access

Award Date

2017

Degree Name

Master of Science (MS)

Department

Veterinary and Biomedical Sciences

First Advisor

Christopher C. L. Chase

Keywords

Bovine viral diarrhea virus, immunosuppression, innate immune response, neutrophil extracellular trap, Neutrophils, oxidative burst

Abstract

Bovine viral diarrhea virus (BVDV) is one of the highly prevalent and economically important diseases of cattle industry worldwide. The two major consequences of this disease are persistent infection and immunosuppression. Several studies have been done to determine the underline mechanisms of BVDV-induced immunosuppression targeting antigen presenting cells, adaptive immune system cells and cytokine gene expression. However, very little research has been done to determine the effect of BVDV on neutrophils. Neutrophils are one of the most abundant while blood cells (WBC) in the peripheral blood, which play a critical role in the innate as well as adaptive immune response. The current study measured the effect of BVDV infection on viability of neutrophils, their surface marker expression and functional abilities including migration/chemoattraction, phagocytosis, reactive oxygen species production (oxidative burst) and neutrophil extracellular trap (NET) formation. These studies revealed that none of BVDV strains affected the viability of neutrophils in vitro. BVDV infection did affect surface marker expression. TGAC and TGAN reduced the expression of CD18 and Lselectin while increasing CD14 expression. All ncp BVDV strains used enhanced neutrophil migration while the cp BVDV strain reduced neutrophil migration as compared to mock-infected control treatment. Among the BVDV strains used in current study, highly virulent 1373 significantly enhanced neutrophil migration. The enhancement in neutrophil migration by 1373 was approximately 55% higher as compared to LPS-treated positive control macrophages. BVDV infection significantly enhanced neutrophil phagocytosis activity for 0.2 μm microsphere beads as compared to mock infection. Neutrophil phagocytic activity for rhodamine-labeled E. coli was reduced by BVDV infection as compared to LPS-control. TGAC, TGAN, 1373 or 28508 had 23%, 6%, 19% or 12% less phagocytic activity respectively as compared to mock-infected rhodamine-labeled E. coli-treated neutrophils. All BVDV strains used in the current study also reduced oxidative burst by approximately 50% as compared to positive control (p

Library of Congress Subject Headings

Bovine viral diarrhea virus.
Neutrophils -- Immunology.
Natural immunity.
Immunosuppression.
Cattle -- Viruses.

Description

Includes bibliographical references

Format

application/pdf

Number of Pages

131

Publisher

South Dakota State University

Rights

Copyright © 2017 Neelu Singh Thakur

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