Skip to main content
ARS Home » Midwest Area » Bowling Green, Kentucky » Food Animal Environmental Systems Research » Research » Publications at this Location » Publication #399517
Research Project: Developing Safe, Efficient and Environmentally Sound Management Practices for the Use of Animal Manure

Location: Food Animal Environmental Systems Research

Title: Identification of virulence genes of Mycoplasma bovis by transposon mutation coupled with in vivo infection

Author
item GELGIE, AGA - University Of Tennessee
item GILLESPIE, BARBARA - University Of Tennessee
item Agga, Getahun
item ALMEIDA, RAUL - University Of Tennessee
item LYSNYANSKY, INNA - Kimron Veterinary Institute
item SHPIGEL, NAHUM - Hebrew University Of Jerusalem
item KERRO DEGO, OUDESSA - University Of Tennessee

Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 12/12/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Mycoplasma bovis is one of major contagious mastitis pathogens in the United States. Its virulence factors and pathogenesis are not well understood which hampered the development of effective prevention and control tools. The objective of this study was to determine important virulence factors of M. bovis by transposon mutagenesis and evaluation of pathogenicity of the mutant clones using experimental infection of dairy cows. Transposon mutant library of M. bovis strain PG45 (wild type) was created and screened for loss of pathogenicity in vitro on mammary epithelial cells and in vivo on mice model. Two less pathogenic clones (Mutants 1 and 2) were selected and further tested by intramammary infection in dairy cows. A total of 12 Holstein dairy cows in 1st-4th parity were divided into 4 groups of 3 cows each. Groups 1 and 2 (controls) were given intramammary infusion of sterile phosphate buffered saline (PBS, pH 7.4) and wild type strain respectively into contralateral quarters. Similarly, Groups 3 and 4 received mutant 1 (M1) and 2 (M2) respectively. Systemic and local clinical signs of mastitis, milk somatic cells count, and M. bovis counts in milk were monitored for 7 days post challenge. After 7 days, cows were euthanized and gross pathological changes recorded. Udder tissue samples were collected for histopathology and swab samples were collected from uterus, joints, lung, and middle ear for culture. Wild type strain and mutant 1 caused mastitis in challenged quarters whereas PBS and mutant 2 infused cows did not develop mastitis. Joint and uterus swab samples from wild type and mutant 1 infected cows were positive for challenge strain M. bovis. Mutated gene in mutant 2 may be critically important to cause mastitis but this need to be confirmed by challenge infection with mutation complemented mutant 2.