Figure 8. Effect of anti-Pat1 and anti-Pat2 antibody pretreatment on R. typhi infectivity of Vero76 cells by IFA.

Rickettsiae were treated with 2 µg of affinity purified anti-Pat1, anti-Pat2 or pre-immune IgG (PI) for 30 min on ice, followed by incubation for infection of Vero76 for 18 hour at 34°C and 5% CO₂. The infected cells were labeled for IFA and % infectivity was determined as described (see Materials and Methods). Infectivity (%) was determined in % host cells infected by R. typhi pretreated with anti-Pat1 or anti-Pat2 antibody with respect to that with PI. Error bars represent standard errors of the means. Infectivity (%) of anti-Pat1 or anti-Pat2 antibody pretreated R. typhi was found to be significantly different (P<0.05[two-tail t-test]) from that of PI.