Serological immune response against major secretory proteins expressed by Pseudomonas aeruginosa upon intratracheal infection in mice

Abstract

Antimicrobial-resistant Pseudomonas aeruginosa is an opportunistic pathogen that severely affects human health. Immunotherapy has attracted substantial attention as an alternative treatment to decrease antimicrobial drug use. Considering previous studies on antibody and vaccine therapy, we focused on quantifying antibodies specific to the V antigen (PcrV) and type III secretory protein (ExoU) expressed by P. aeruginosa to evaluate the serological immune response. We intratracheally infected male ICR mice with several P. aeruginosa strains and quantified antigen-specific antibody titers across 8 weeks. Intratracheal infection of P. aeruginosa PA103 at a sublethal dose decreased the body temperature of mice. The IgG and IgA serum titers against PcrV and ExoU did not increase over 8 weeks, and the IgM titer initially increased for 4 weeks and then decreased. Specific antibodies against PcrV and ExoU may be difficult to produce naturally. Therefore, the IgM expression against major secretory proteins of P. aeruginosa is critical.

Keywords: Antibody titers; ExoU; Innate immune response; Pseudomonas aeruginosa; V antigen.