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Table 2 Oral immunization with the PspA-expressing S. Typhimurium χ9241 (pYA4088) vaccine and χ12358 (pYA4088) protected BALB/c mice against a challenge with the virulent S. pneumoniae strain WU2

From: Effect of deletion of gene cluster involved in synthesis of Enterobacterial common antigen on virulence and immunogenicity of live attenuated Salmonella vaccine when delivering heterologous Streptococcus pneumoniae antigen PspA

Vaccine PspA expressiona Total mice/group Survival/totalb Percent protectionb
χ12358 (pYA4088) + 12 4/12 33%
χ9241 (pYA4088) + 12 4/12 33%
χ9241 (pYA3493) 12 0/12 0%
  1. a +, PspA expressed; −, PspA not expressed
  2. b Mice were challenged with 4 × 104 CFU of S. pneumoniae WU2 (50 times LD50) 4 weeks after the second immunization