Invasive group A Streptococcus disease in French-Canadian children is not associated with a defect in MyD88/IRAK4-pathway.
BACKGROUND
Beta-hemolytic Group A Streptococcus invasive disease (iGASd) has been subject to intense research since its re-emergence in the late 1980s. In Quebec, an increase in the number of severe iGASd cases has recently been observed. Because of the inter-individual variability in the severity of iGASd, a hereditary predisposition to invasive disease can be suspected. Given that iGASd occurs in MyD88- and IRAK4-deficient patients, although rarely, the increasing frequency of iGASd in the population of French-Canadian children may be associated with a deficiency in the host's innate immune response.


METHODS
In this report, we assessed the influence of: (i) bacterial genotype and virulence factors, (ii) immune-cellular features, and (iii) Myd88/IRAK4-dependent response to GAS in vitro on the susceptibility to iGASd in a paediatric cohort of 16 children: 11 French-Canadian and 5 from diverse origin.


RESULTS
GAS virulence factors and genotype are not implicated in the susceptibility toward iGASd, and cellular and MyD88/IRAK4 deficiencies are excluded in our patients.


CONCLUSIONS
Although it has been shown that the MyD88/IRAK4-dependent signal is involved in the response to invasive GAS, our data indicates that a MyD88/IRAK4-mediated signalling defect is not the main factor responsible for the susceptibility to severe iGASd in a paediatric population from the province of Quebec.
Department of Microbiology, Infectiology and Immunology, CHU Sainte-Justine and University of Montreal, Montreal (Quebec), Canada. isabel.fernandez.hsj@ssss.gouv.qc.ca.
Isabel
I
Fernandez
Rose-Marie
RM
Brito
Philippe
P
Bidet
Fabien
F
Rallu
Celine
C
Laferrière
Philippe
P
Ovetchkine
Francoise
F
Le Deist