Staphylococcus pseudintermedius SPDSa inhibits the innate immune response and promotes bacterial survival in canine blood

8^th International Conference on Animal Health & Veterinary Medicine

October 20-21, 2017 | Toronto, Canada

Mohamed Abouelkhair, David A Bemis and Stephen A Kania

University of Tennessee, USA

Posters & Accepted Abstracts: J Vet Sci Technol

Abstract :

Staphylococcus pseudintermedius is an important opportunistic bacterial pathogen that is the most common cause of canine pyoderma. It is frequently associated with urinary tract, wound and surgical site infections and occasionally causes zoonotic infections in human beings. The development of a staphylococcal vaccine is challenging and prior infection with S. pseudintermedius is not associated with protective immunity. Identification of a novel virulence factor inhibiting phagocytosis and evasion of innate immunity could play an important role in the prevention or treatment of S. pseudintermedius infection. Here, through bioinformatics- based analysis of S. pseudintermedius genome sequences, we identified a putative adenosine synthase gene (SpdsA) encoding a 5-nucleotidase. S.pseudintermedius SpdsA protein shares approximately 73.46% similarity with that of S. aureus and 46.44% similarity with that of S. suis type 2. Like the orthologous protein in Staphylococcus aureus it catalyzes the dephosphorylation of adenosine mono- and triphosphates and consequently produces the immune signaling molecule adenosine. Attenuation of this enzyme with selected amino acid substations resulted in diminished hydrolytic activity on adenosine mono-and triphosphates and reduced adenosine production. Adenosine perturbation enabled escape of S. pseudintermedius from phagocytic clearance in dog blood. In contrast, the addition of SPDSa inhibitor or A2A receptor antagonist to phagocytic cells resulted in diminished ability of S. pseudintermedius to escape from phagocytic killing. Taken together, these results indicate that SpdsA may play an important role in promoting S. pseudintermedius survival and in inhibiting neutrophil activity by adenosine synthesis.