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Open Access Highly Accessed Research article

NADase as a target molecule of in vivo suppression of the toxicity in the invasive M-1 group A Streptococcal isolates

Ichiro Tatsuno, Masanori Isaka, Masaaki Minami and Tadao Hasegawa*

Author Affiliations

Department of Bacteriology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi Mizuho-cho Mizuho-ku, Nagoya 467-8601, Japan

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BMC Microbiology 2010, 10:144  doi:10.1186/1471-2180-10-144

Published: 17 May 2010

Abstract

Background

NAD-glycohydrolase (NADase) secreted by M-1 group A streptococcal (GAS) isolates are suspected as one of the virulence factors to cause severe invasive disease including streptococcal toxic shock-like syndrome (STSS). M-1 GAS strains were divided into three groups based on NADase activity: high activity, low activity and no activity in our previous report.

Results

The representative high activity isolates taken from STSS patients showed higher virulence compared with isolates from the low activity group, when used to infect mice. The knockout mutant of the nga gene, which encodes NADase also showed reduced virulence in a mouse infection study. The cloned nga gene was able to significantly complement the lost virulence. In addition, the solution containing purified recombinant IFS, which is an inhibitor of NADase, partially rescued mice infected with S. pyogenes.

Conclusions

These results indicate that NADase is important for the virulence of S. pyogenes in vivo and is the potential target to suppress the virulence.