Table 5.

Passive protection of mice from fatal pneumococcal infection with anti-PspA serum from mice orally immunized withS. typhimuriumχ4550(pYA3193)a

Challenge dose (log10)Challenge routePassive serum administeredSerum dilutionDays to deathP value vs PspA immuneb
3.7i.v.Nonimmune1/21, 1, 1, 1, 2, 2, 2, 2, 20.007
i.v.Vector immune2, 2, 3, 4, 40.029
i.v.PspA immune1/21, >21, >21, >21, >21, >21, >21, >21, >21
3.9i.v.Nonimmune1/101, 2, 2, 2, 2, 20.0086
i.v.PspA immune1/102, 3, 3, 4, >15, >15
3.0i.p.Nonimmunec1/52, 2, 2, 3, 3, 3, 40.038
i.p.PspA immune1/52, 3, 4, 5, >15, >15, >15
  • a i.v. challenge studies were conducted with CBA/N recipients; i.p. challenge studies were conducted with BALB/cJ recipients.

  • b P values comparing the days to death were calculated by using the Wilcoxon two-sample rank test between mice given PspA-immune sera and mice receiving vector-immune or nonimmune serum. In the case of the i.p. challenge, the P value was calculated between immune and the pooled data for nonimmune serum and no serum.

  • c Includes two mice which received no serum.