StreptInCor: a candidate vaccine epitope against S. pyogenes infections induces protection in outbred mice

• Published in: PloS one 2013-04, Vol.8 (4), p.e60969-e60969
• Main Authors: Postol, Edilberto, Alencar, Raquel, Higa, Fabio T, Freschi de Barros, Samar, Demarchi, Lea M F, Kalil, Jorge, Guilherme, Luiza
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amino acids; Animals; Antibodies; Antibody Specificity; Antigen-antibody reactions; Antigenic determinants; Bacterial Adhesion - immunology; Bacterial infections; Bacterial Vaccines - chemistry; Bacterial Vaccines - immunology; Biology; Blood cells; Breeding; Cardiovascular disease; Cell Line; Cell Proliferation; Children; Complications; Cross-reaction; Epidemiology; Epitopes; Epitopes - immunology; Female; Fever; Genetic engineering; Heart; Heart diseases; Histocompatibility antigen HLA; Humans; Immune response; Immune response (cell-mediated); Immunization; Immunoglobulin G - immunology; Immunology; Infection; Infections; Lymphocytes; Lymphocytes T; M protein; Medicine; Mice; Molecular Sequence Data; Muscle proteins; Myosin; N-Terminus; Pediatrics; Peptides; Peripheral blood; Pharyngitis; Polymorphism, Genetic; Proteins; Rheumatic fever; Science; Species Specificity; Spleen - cytology; Streptococcal Infections - blood; Streptococcal Infections - genetics; Streptococcal Infections - prevention & control; Streptococcus; Streptococcus infections; Streptococcus pyogenes - immunology; Streptococcus pyogenes - physiology; T cells; Transgenic animals; Transgenic mice; Vaccines; Vaccines, Subunit - chemistry; Vaccines, Subunit - immunology; Virulence; Virulence factors
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0060969

Infection with Streptococcus pyogenes (S. pyogenes) can result in several diseases, particularly in children. S. pyogenes M protein is the major virulence factor, and certain regions of its N-terminus can trigger autoimmune sequelae such as rheumatic fever in susceptible individuals with untreated group A streptococcal pharyngitis. In a previous study, we utilized a large panel of human peripheral blood cells to define the C-terminal protective epitope StreptInCor (medical identity), which does not induce autoimmune reactions. We recently confirmed the results in HLA-transgenic mice. In the present study, we extended the experimental assays to outbred animals (Swiss mice). Herein, we demonstrate high titers of StreptInCor-specific antibodies, as well as appropriate T-cell immune responses. No cross-reaction to cardiac myosin was detected. Additionally, immunized Swiss mice exhibited 87% survival one month after challenge with S. pyogenes. In conclusion, the data presented herein reinforce previous results in humans and animals and further emphasize that StreptInCor could be an effective and safe vaccine for the prevention of S. pyogenes infections.