DRS is far less divergent than streptococcal inhibitor of complement of group A streptococcus

Abstract

When 100 group A streptococcus isolates were screened, drs, a variant of sic, was identified in emm12 and emm55 isolates. Molecular characterization showed that the drs gene sequence is highly conserved, unlike the sic gene sequence. However, the variation in gene size observed was due to the presence of extra internal repeat sequences.

FIG. 1.

Characterization of DRS. (A) PCR analysis of drs. Lane M, 100-bp ladder (NEB); lane 1, M12 reference strain used as a positive control; lane 2, representative emm12 clinical isolate; lane 3, emm55 clinical isolate; lane (−), negative control with no template. (B) Comparison of the amino acid sequences of Indian DRS12 (I) and DRS55 (I) with Australian DRS12 (A) and DRS55 (A) by multiple-sequence alignment. Asterisks indicate a conserved sequence; underlining indicates an additional repeat sequence; and a sequence not available in the gene bank database is indicated by question marks. (C) Western blot analysis showing expression of DRS. Lane 1, M12 reference strain used as a positive control; lane 2, DRS negative control; lane 3, representative emm12 isolate; lane 4, emm55 isolate.