Development and Characterization of a Recombinant galT-galU Protein for Broad-Spectrum Immunoprotection Against Porcine Contagious Pleuropneumonia

TL;DR

Researchers developed a new protein vaccine that offers broad protection against a deadly pig lung disease caused by Actinobacillus pleuropneumoniae.

Contribution

A recombinant galT-galU protein was created and shown to provide cross-protective immunity against multiple strains of APP.

Findings

The rgalT-galU protein induced strong immune responses in mice, including elevated IgG and cytokine levels.

Vaccination with rgalT-galU protected against three major APP strains with protection rates up to 85.7%.

The vaccine reduced lung damage and neutrophil infiltration in infected pigs.

Abstract

Porcine contagious pleuropneumonia (PCP), caused by Actinobacillus pleuropneumoniae (APP), is a highly contagious disease that leads to significant economic losses in the swine industry. Current vaccines are ineffective due to the presence of multiple serotypes and the absence of a predominant seasonal serotype, underscoring the need for vaccines with broad-spectrum protection. Previous studies identified galT and galU as promising antigen candidates. In this study, we expressed and characterized a soluble recombinant galT-galU protein (rgalT-galU) from the pET-28a-galT-galU plasmid. The protein, with a molecular weight of 73 kDa, exhibited pronounced immunogenicity in murine models, as indicated by a significant elevation in IgG titers determined through an indirect ELISA. This immune response was further corroborated by substantial antigen-specific splenic lymphocyte proliferation, with a stimulation index of 51.5%. Immunization also resulted in elevated serum cytokines levels of IL-4, IL-12, and IFN-γ, as detected by cytokine assays. Vaccination with rgalT-galU provided immunoprotection against three predominant APP strains (APP1, APP5b, and APP7), achieving protection rates of 71.4%, 71.4%, and 85.7%, respectively. It also effectively mitigated pulmonary lesions and neutrophil infiltration, as verified by histopathological and immunohistochemical analyses. These results indicate that rgalT-galU is a promising candidate for developing cross-protective subunit vaccines against APP infection.

Figures