Background: The relation of nephritis-associated plasmin receptor (NAPlr) as a nephritogenic antigen in group A streptococci (GAS), to acute poststreptococcal glomerulonephritis (APSGN) and the potential of specific strains to cause APSGN are not fully understood. It would be helpful to determine whether certain GAS strains from APSGN patients specifically express NAPlr and whether strains from non-APSGN patients express lower levels or an altered form of NAPlr.
Methods: The sequence and levels of expression of NAPlr were assayed for strains of GAS isolated from patients with APSGN, pharyngitis, scarlet fever or toxic shock-like syndrome. Findings were evaluated with respect to naplr gene sequence, expression level of NAPlr, serotype and disease type.
Results: In GAS strains from both APSGN and non-APSGN patients, the naplr gene showed few or no nucleotide alterations, and both types of GAS strains expressed NAPlr in vitro. There were no obvious differences in naplr gene sequence, expression of NAPlr, serotype or disease type between the GAS strains. In addition, groups C and G streptococci also carried a conserved naplr gene and expressed NAPlr in vitro.
Conclusions: These groups of streptococci that express NAPlr should be associated with APSGN, and this association may be independent of serotype or disease type.