title: Sialic acid-dependent interactions between influenza viruses and Streptococcus suis affect the infection of porcine tracheal cells.
abstract: Bacterial co-infections are a major complication in influenza-virus-induced disease in both humans and animals. Either of the pathogens may induce a host response that affects the infection by the other pathogen. A unique feature in the co-infection by swine influenza viruses (SIV) and Streptococcus suis serotype 2 is the direct interaction between the two pathogens. It is mediated by the haemagglutinin of SIV that recognizes the α2,6-linked sialic acid present in the capsular polysaccharide of Streptococcus suis. In the present study, this interaction was demonstrated for SIV of both H1N1 and H3N2 subtypes as well as for human influenza viruses that recognize α2,6-linked sialic acid. Binding of SIV to Streptococcus suis resulted in co-sedimentation of virus with bacteria during low-speed centrifugation. Viruses bound to bacteria retained infectivity but induced only tiny plaques compared with control virus. Infection of porcine tracheal cells by SIV facilitated adherence of Streptococcus suis, which was evident by co-staining of bacterial and viral antigen. Sialic-acid-dependent binding of Streptococcus suis was already detectable after incubation for 30 min. By contrast, bacterial co-infection had a negative effect on the replication of SIV as indicated by lower virus titres in the supernatant and a delay in the kinetics of virus release.
authors: Institute of Virology, University of Veterinary Medicine Hannover, Hannover, Germany.
authors: Nai-Huei
authors: NH
authors: Wu
authors: Institute of Virology, University of Veterinary Medicine Hannover, Hannover, Germany.
authors: Fandan
authors: F
authors: Meng
authors: Institute of Microbiology, University of Veterinary Medicine Hannover, Hannover, Germany.
authors: Maren
authors: M
authors: Seitz
authors: Institute of Microbiology, University of Veterinary Medicine Hannover, Hannover, Germany.
authors: Peter
authors: P
authors: Valentin-Weigand
authors: Institute of Virology, University of Veterinary Medicine Hannover, Hannover, Germany.
authors: Georg
authors: G
authors: Herrler
mesh_terms: D000818:Animals; D060085:Coinfection / Q000382:microbiology / Q000821:virology; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000378:metabolism; D053118:Influenza A Virus, H1N1 Subtype / Q000378:metabolism*; D053122:Influenza A Virus, H3N2 Subtype / Q000378:metabolism*; D019158:N-Acetylneuraminic Acid / Q000378:metabolism*; D009976:Orthomyxoviridae Infections / Q000662:veterinary* / Q000821:virology; D011485:Protein Binding; D013290:Streptococcal Infections / Q000382:microbiology*; D017011:Streptococcus suis / Q000378:metabolism*; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology* / Q000821:virology*; D014132:Trachea / Q000382:microbiology / Q000821:virology
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D019158:N-Acetylneuraminic Acid