Streptococcus suis type 2 culture supernatant enhances the infection ability of the Swine influenza virus H3 subtype in MDCK cells.

Abstract

Swine Influenza virus and Streptococcus suis type 2 often occur as a clinical coinfection in pigs, the syndrome of which is more serious than the virus or bacterium sole infection. Streptococcus suis type 2 can produce extracellular proteases, which may cleave hemagglutinin to enhance the infection ability of Swine Influenza virus. The current study investigated whether extracellular proteolytic culture supernatant of Streptococcus suis type 2, isolated from Jiangsu, enhanced the infection ability of H3N2 Swine Influenza virus (A/Swine/Guangdong/4/2003) on MDCK cells. Our data suggested that exposure of MDCK cells to culture supernatant of Streptococcus suis type 2 enhanced the cytopathic effect produced by Swine Influenza virus, hemagglutination of cell culture supernatants and FITC immunofluorescence intensity.