IMMUNIZATION WITH A PLASMID EXPRESSING PNEUMOCOCCAL SURFACE PROTEIN-A(PSPA) CAN ELICIT PROTECTION AGAINST FATAL INFECTION WITH STREPTOCOCCUS-PNEUMONIAE
Ls. Mcdaniel et al., IMMUNIZATION WITH A PLASMID EXPRESSING PNEUMOCOCCAL SURFACE PROTEIN-A(PSPA) CAN ELICIT PROTECTION AGAINST FATAL INFECTION WITH STREPTOCOCCUS-PNEUMONIAE, Gene therapy, 4(4), 1997, pp. 375-377
Pneumococcal surface protein A (PspA) is a protection-eliciting protei
n of Streptococcus pneumoniae. We observed that immunization of BALB/c
mice with a plasmid expressing PspA significantly protected the mice
from lethal challenge with S. pneumoniae when compared to control mice
that received injections of the plasmid vector alone. The plasmid con
struct expressing PspA has been designated pKSD2601. Mice immunized in
tramuscularly with pKSD2601 had a mean log of colony-forming units of
2.97+/-0.25 pneumococci circulating in their blood at 24 h after chall
enge as compared with control mice that had a mean log of colony-formi
ng units of 4.95+/-0.59. Those mice with lower numbers of pneumococci
subsequently survived the challenge. Given the quantitative nature and
ultimate end point (ie live versus dead) our mouse model should be us
eful in working out optimum expression of bacterial genes for DNA immu
nization.