Virulence factors and immune mechanisms of group A streptococci infection
Medical Review (Med. pregled), 2024, 60(2), 16-21.
I. Altаnkova1, I. Ivanova2, S. Petkov2, A. Kukov2, Y. Uzunova3, E. Keuleyan4
1 Laboratory “Clinical Immunology” – UMHAT “Lozenets”, MF of SU “Sv. Kl. Ohridski”
2 Laboratory “Clinical Immunology” – UMHAT “Lozenets”
3 Clinic “Pediatrics” – UMHAT “Lozenets”, MF of SU “ Sv. Kl. Ohridski “
4 Laboratory “Clinical Microbiology” – UMHAT “Lozenets”
Abstract. Streptococcus pyogenes, the Group A Streptococcus (GAS), is the most common cause of bacterial pharyngitis, scarlet fever, impetigo etc. in children and adults. Innate and adaptive host immune responses are fundamental for defense against GAS and are central to the clinical manifestations of the infection. For the purposes of this review, we consider GAS virulence factors as possible inducers and modulators of anti-GAS immune responses in the infected individuals. These include M-proreins, the hyaluronic acid capsule, superantigens, enzymes that break down immunoglobulins, factors causing modulation of neutrophils, complement and chemokine functions. Different cells are taking parts in the innate and adaptive immune responses against GAS, which are reported to secrete a number of soluble inflammatory mediators, such as antimicrobial peptides, chemokines, and proinflammatory cytokines. An essential role is played by the so called lymphocytes of the innate immunity, which secrete IFN-γ, TNFα and IL-2, preparing the subsequent specific anti-GAS immune response. Th-1, Th-17 cell subsets and the cytokines IL-6, TNFα, IFN-γ etc., produced by them mediate further specific inflammatory responses. In conclusion, our review shows that S. pyogenes possesses a constellation of virulence factors and induces strong, early, innate and acquired immune responses, often leading to clinical diseases.
Key words: Streptococcus pyogenes, GAS, innate and adaptive immune responses against GAS
Address for correspondence: Prof. Dr. Iskra Altankova, е-mail: altankova@abv.bg