Synergistic effects of streptolysin S and streptococcal pyrogenic exotoxin B on the mouse model of group A streptococcal infection.

Abstract

Streptococcus pyogenes is a group A streptococcus (GAS) and an important human pathogen that causes a variety of diseases. Streptococcal pyrogenic exotoxin B (SPE B) and streptolysin S (SLS) are important virulence factors involved in GAS infection, but it is not clear which one is more virulent. Using an air pouch infection model, the wild-type strain NZ131, its isogenic mutants, and complementary mutants were used to examine the effects of SPE B and SLS on GAS infection. The results of the skin lesion and mouse mortality assays showed that although SPE B and SLS had a synergistic effect on GAS infection, SPE B played a more important role in local tissue damage while SLS had a more prominent effect on mouse mortality. Surveys of the exudates from the air pouch revealed that the expression of inflammatory cytokines was significantly inhibited in the sagB/speB-double-mutant JM4-infected mice. Furthermore, in vivo and in vitro studies showed that the isogenic mutant strains were more susceptible to the immune cell killing than the wild-type strain and that the sagB/speB-double-mutant JM4 was the most sensitive among these strains. Moreover, infection with the sagB/speB-double-mutant JM4 strain caused the least amount of macrophage apoptosis compared to infection with the wild-type NZ131 and the other complementary strains, which express only SPE B or SLS or both. Taken together, these results indicate that both SPE B and SLS contributed to GAS evasion from immune cell killing, local tissue damage, and mouse mortality.

• Authors: Chih-Hsin Hung, Nina Tsao, Yi-Fang Zeng, Shiou-Ling Lu, Chiang-Ni Chuan, Yee-Shin Lin, Jiunn-Jong Wu, Chih-Feng Kuo
• Journal: Medical microbiology and immunology (Med Microbiol Immunol) Vol. 201 Issue 3 Pg. 357-69 (Aug 2012) ISSN: 1432-1831 [Electronic] Germany
• PMID: 22610375 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Bacterial Proteins
• Exotoxins
• Streptolysins
• Virulence Factors
• erythrogenic toxin
• streptolysin S

Topics

• Animals
• Bacterial Proteins (genetics, metabolism)
• Disease Models, Animal
• Drug Synergism
• Exotoxins (genetics, metabolism)
• Humans
• Immune Evasion
• Male
• Mice
• Mice, Inbred BALB C
• Streptococcal Infections (immunology, microbiology, mortality, pathology)
• Streptococcus pyogenes (genetics, pathogenicity)
• Streptolysins (genetics, metabolism)
• Virulence
• Virulence Factors (genetics, metabolism)