Presence of fibronectin-binding protein gene prtF2 in invasive group A streptococci in tropical Australia is associated with increased internalisation efficiency.
The fibronectin-binding proteins (FnBPs) PrtF1 and PrtF2 are considered to be major group A streptococcal virulence factors, mediating adherence to and internalisation of host cells. The present study investigated an association between the presence of prtF1 and prtF2 genes and internalisation efficiency in group A streptococci (GAS) isolated from patients with invasive disease. Of the 80 isolates tested, 58 (73%) had prtF1 and 71 (89%) possessed prtF2. Three isolates (4%) had neither gene, seven (9%) had prtF1 only, 19 (24%) had prtF2 only and 51 isolates (64%) had both prtF1 and prtF2. prtF2-positive isolates internalised up to three times more efficiently than isolates that had prtF1 alone (P<0.001), and 1.5-fold better than isolates that had neither gene. No significant association was found between internalisation efficiency and presence of the prtF1 gene. Analysis of the fibronectin-binding repeat domain (FBRD) of prtF2 revealed that this gene can contain 2, 3, 4 or 5 repeat regions and that five repeat regions conferred very high internalisation efficiency in invasive GAS isolates.
Gorton
Davina
D
School of Veterinary and Biomedical Sciences, James Cook University, Townsville 4811, Australia.
Norton
Robert
R
Layton
Ramon
R
Smith
Helen
H
Ketheesan
Natkunam
N
D018829:Adhesins, Bacterial / Q000235:genetics*; D000595:Amino Acid Sequence; D001315:Australia / Q000453:epidemiology; D006801:Humans; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D013290:Streptococcal Infections / Q000453:epidemiology / Q000382:microbiology; D013297:Streptococcus pyogenes / Q000235:genetics* / Q000472:pathogenicity
D018829:Adhesins, Bacterial; C078635:fibronectin-binding proteins, bacterial