Deceiving to better invade: The porcine influenza virus helps Streptococcus suis infections!

A collaborative project among members of the Swine and Poultry Infectious Diseases Research Centre (CRIPA) led by Dr. Marcello Gottschalk’s team, involving Drs. Carl A. Gagnon and Mariela Segura, has shown that a sugar covering the surface of S. suis bacteria called sialic acid interacts with the haemagglutinin protein found on the surface of porcine influenza virus. The interaction between sialic acid and haemagglutinin increases adherence to porcine cells and, therefore, promotes dissemination within the host. Interestingly, since S. suis is already able to invade cells found in a healthy trachea, we are wondering why the bacterium pairs up with this virus? We already knew that the trachea acts as an entry point for S. suis to disseminate into the blood stream, which provides a nutrient-rich environment for the bacteria to grow in. With the financial support of NSERC, these researchers at the Faculty of veterinary medicine at the Université de Montréal have discovered that the partnership between S. suis and porcine influenza virus acts to over-stimulate the immune system. In fact, this duo directs the immune response to amplify inflammation, which induces more lesions in the pigs. It seems that this bacterium has found a partner in crime to smooth out the ride on the way to achieving it’s goals!

Capsular sialic acid of Streptococcus suis serotype 2 binds to swine influenza virus and enhances bacterial interactions with virus-infected tracheal epithelial cells. Wang Y, Gagnon CA, Savard C,

Music N, Srednik M, Segura M, Lachance C, Bellehumeur C, Gottschalk M. Infection and Immunity, December 2013.