Hydrogen peroxide-inactivated bacteria induces potent humoral and cellular immune responses and releases nucleic acids.

The problem of nosocomial infection is seriously escalating. Bacterial vaccines are indispensable for preventing infections caused by multi-drug resistant organisms. Some researchers have put forward the use of hydrogen peroxide (H2 O2 ) as a new technology platform for virus deactivation. This deactivated virus can induce the number of CD8+ T lymphocytes, which can enhance antiviral responses. Although, H2 O2 treatment has been rarely reported on the exploration of bacterial deactivation, H2 O2 deactivation of whole-cell bacteria could be a potential novel approach for bacterial vaccine development. Here we present a strategy for H2 O2 -deactivated bacterial whole-cell vaccines, for two major pathgens, Pseudomonas aeruginosa and Staphylococcus aureus. The proactive effects of vaccination were assessed in vitro and in vivo. H2 O2 -deactivation of bacterial vaccines retains more complete epitopes and exhibits lower toxicity, as compared to formaldehyde, a conventional deactivator that was investigated in this study. Furthermore, H2 O2 -deactivated bacterial vaccines induce anti-infection responses through enhancement of humoral immunity and cellular immunity. Vaccination with H2 O2 -deactivated whole-cell bacteria in mice mainly elicits whole-cell specific antibody titers and balances the IgG2a and IgG1 response, predominantly with IgG3 induction at the later stages, meanwhile provides opsonic protection against challenge with pathogens. Finally, H2 O2 deactivation of bacteria has been found to cause the release of bacterial DNA which is followed by NF-κB activation. These findings demonstrate that the deactivation of whole-cell bacteria with H2 O2 is potentially advantageous for immune responses. Considering the prevention of drug-resistant infections, this deactivation method could be simultaneously applied as an innovative strategy for bacterial vaccine development.