TABLE 1.

Bacterial strains and plasmids used in this study

Strain or plasmidGenotype or relevant characteristicsSource or reference
Strains
    Escherichia coli χ7213 thi-1 thr-1 leuB6 glnV44 fhuA21 lacY1 recA1 ΔasdA4 Δ(zhf-2::Tn10) RP4-2-Tc::Mu[λ pir] 39
    S. Typhimurium
        χ3761Wild-type UK-1 14
        χ9558Δpmi-2426 Δ(gmd-fcl)-26 ΔPfur81::TT araC PBADfur ΔPcrp527::TT araC PBADcrp ΔasdA27::TT araC PBADc2 ΔaraE25 ΔaraBAD23 ΔrelA198::araC PBADlacI TT ΔsopB1925 ΔagfBAC811 6
    S. pneumoniae WU2Wild type, virulent, encapsulated, type 3 8
Plasmids
    pYA3493Asd+ pBRori β-lactamase signal sequence-based periplasmic secretion plasmid 6
    pYA4088852-bp DNA encoding the α-helical region of PspA from aa 3 to 285 in pYA3493 49