CSPP1-E1A attenuates the ability of cap3A mutant S. pneumoniae to acquire capsule gene during natural transformation in mouse peritoneal cavity.

Mice were intraperitoneally infected with S. pneumoniae cap3A mutant bacteria (3×109, 100 µl volume) supplemented with 100 µg of chromosomal DNA from the parental wild-type strain 0100993 in the presence or absence of 100 µg CSP1-E1A or CSP1-R3A. Mouse spleens were harvested at 24 hr post-infection, homogenized, serially diluted and plated on THB agar for enumeration of mucoid colonies.