Evaluation of the Immunomodulatory Properties of Streptococcus suis and Group B Streptococcus Capsular Polysaccharides on the Humoral Response

• Published in: Pathogens (Basel) Vol. 6; no. 2; p. 16
• Main Authors: Calzas, Cynthia, Taillardet, Morgan, Fourati, Insaf Salem, Roy, David, Gottschalk, Marcelo, Soudeyns, Hugo, Defrance, Thierry, Segura, Mariela
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 20.04.2017; MDPI
• Subjects: Acids; Antibodies; Antibody response; Bacteriology; Capsular polysaccharides; Immune response (humoral); Immune system; Immunization; Immunogenicity; Immunoglobulin M; Immunology; Immunomodulation; Life Sciences; Meningitis; Mice; Microbiology and Parasitology; Polysaccharides; Protective structures; Rodents; Saccharides; Septicemia; Serotypes; Streptococcus; Streptococcus infections; Sugar; Switching; Virology; group B Streptococcus; capsular polysaccharide; sialic acid; Streptococcus suis; humoral response; murine B cells
• ISSN: 2076-0817; 2076-0817
• DOI: 10.3390/pathogens6020016

and group B (GBS) are encapsulated streptococci causing septicemia and meningitis. Antibodies (Abs) against capsular polysaccharides (CPSs) have a crucial protective role, but the structure/composition of the CPS, including the presence of sialic acid, may interfere with the generation of anti-CPS Ab responses. We investigated the features of the CPS-specific Ab response directed against serotypes 2 and 14 and GBS serotypes III and V after infection or immunization with purified native or desialylated CPSs in mice. Whereas -infected mice developed a very low/undetectable CPS-specific IgM response, significant anti-CPS IgM titers were measured in GBS-infected animals (especially for type III GBS). No isotype switching was detected in - or GBS-infected mice. While the expression of sialic acid was essential for the immunogenicity of purified GBS type III CPS, this sugar was not responsible for the inability of purified types 2, 14 and GBS type V CPSs to induce a specific Ab response. Thus, other biochemical criteria unrelated to the presence of sialic acid may be responsible for the inaptitude of the host immune system to mount an effective response against certain and GBS CPS types.