Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Hanson, Larry

Committee Member

Wan, Xiu-Feng (Henry)

Committee Member

Olivier, Alicia Kathleen

Committee Member

Wills, Robert W.

Date of Degree

12-13-2019

Original embargo terms

Visible to MSU only for 3 Years

Document Type

Dissertation - Open Access

Major

Veterinary Medical Science

Degree Name

Doctor of Philosophy

Degree Name

Doctor of Philosophy (Ph.D)

College

College of Veterinary Medicine

College

College of Veterinary Medicine

Department

Department of Basic Sciences

Department

Veterinary Medical Science Program

Abstract

Influenza poses a significant global health risk due to the high morbidity and mortality associated with endemic strains and the pandemic potential of novel strains. This research characterizes the zoonotic risk of emerging influenza viruses from domestic animals. Chapter two investigates the genetic compatibility of pandemic H1N1 and emerging canine influenza H3N2 (CIV-H3N2), first identified in dogs in 2007 and currently responsible for outbreaks in shelters in the U.S. We generated 51 of the 127 possible reassortant viruses: 19 showed high-growth phenotypes and 13 replicated in mice lungs. A reassortant with the HA and NP genes derived from CIV-H3N2 transmitted efficiently by direct contact in ferrets and was more pathogenic than wild-type CIV-H3N2. Our results suggest that CIV-H3N2 reassortants may pose a moderate risk to public health and that the canine host should be monitored for emerging FLUAV. Chapter three is a seroepidemiological study of influenza A (FLUAV) exposure in shelter dogs in Mississippi, a population not previously investigated. We sampled 565 dogs from eighteen shelters statewide and identified 7/565 dogs (1.2%) ELISA positive (S/N < 0.70) for FLUAV exposure but no positive dogs by HI assay. Chapter 4 investigates the pathogenicity of emerging influenza D virus (FLUDV), first isolated from symptomatic pigs in 2011. Serology suggests feral swine are exposed to both FLUAV and FLUDV and we investigated whether coinfection with these two viruses enhances pathogenicity in domestic pigs. In single infections, 5/5 pigs shed FLUAV and 6/7 pigs shed FLUDV in nasal swabs; however, in the FLUAV+ FLUDV coinfection group 7/7 pigs shed FLUAV but only 1/7 shed FLUDV. FLUDV replicated better in the turbinate and soft palate of single infection group than the coinfection group, whereas FLUAV replicated equally well in both single and coinfection groups. Our data suggests coinfection is associated with less robust FLUDV replication in pigs. Collectively, this dissertation offers insight into emerging influenza viruses originating in dogs and pigs and potential competitive outcomes associated with coinfection.

URI

https://hdl.handle.net/11668/16465

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