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Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)


Veterinary and Biomedical Sciences

First Advisor

Paulraj Lawrence


Mycoplasma hyosynoviae is a gram negative bacterial parasite that is a common resident of the nasopharyngeal tract in adult swine. Shortly after weaning, at approximately ten weeks of age, the maternal antibody provided by the mother’s colostrum begins to drop in litter and piglets become susceptible to infection with M. hyosynoviae. If a piglet is exposed and its immune response is insufficient the organism may migrate through the bloodstream to the synovial membranes of the joints where it can adhere and cause debilitating arthritis. These symptoms often resolve, even if left untreated. However, the piglet will remain off feed during infection, resulting in a substantial decrease in the rate of weight gained and significant economic losses for the producer. The mechanism by which M. hyosynoviae adheres to the synovial membranes of pigs has not been studied in detail and studies concerning the metabolic requirements of this organism are also lacking in the literature. Therefore, we chose to undertake a comparative genomic study to determine if virulence factors may be present that could be involved in adherence and also to determine what nutritional requirements the organism needs for robust growth. During our comparative analysis we identified several genes that encode homologs of known adhesins including OppA, MAA1, elongation factor G, and elongation factor Tu. We also identified a VapD protein homolog that is involved in the virulence of several other bacterial species. In addition, we identified several genes including lemA, infC, rpmI, and rplT that are involved in regulating secretion of proteases into the host environment. We identified several prophage strains present in many of the strains. In addition, we determined that some strains of M. hyosynoviae possess a CRISPR-Cas system that is likely used in defense against phage infection. Finally, we provide evidence that M. hyosynoviae possesses fluoroquinolone resistance genes and has acquired at least one mutation that confers anti-microbial resistance in other Mycoplasma species. These findings have important implications for the swine production industry and could be utilized to design interventions that may help prevent disease caused by this organism.

Library of Congress Subject Headings

Swine -- Diseases
Mycoplasma diseases in animals
Bacterial diseases in animals
Pathogenic bacteria
Bacterial genetic


Includes bibliographical references (pages 50-60)



Number of Pages



South Dakota State University


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