Design and functional characterization of recombinant chimeras as vaccine candidates against Lawsonia intracellularis.

Proliferative enteropathy is a gastrointestinal disease caused by the intracellular bacterium Lawsonia intracellularis, affecting swine populations worldwide and leading to significant economic losses due to reduced growth performance, increased mortality, and treatment expenses. Current vaccines present limitations related to production processes, stability, and overall cost. This study aimed to design and evaluat chimeric proteins containing immunogenic epitopes of L. intracellularis. A recombinant chimera, designated Li_full, was rationally designed in silico by integrating predicted B-cell and MHC epitopes relevant to swine immunity. To further investigate the immunogenic potential of distinct regions, Li_full was subdivided into three fractions (Li_1, Li_2, and Li_3). All constructs were cloned into an Escherichia coli expression system, allowing efficient production and biochemical characterization of the recombinant proteins. Antigenicity was confirmed by strong reactivity with sera from naturally infected pigs. Immunogenicity was assessed through vaccination in mice, which developed significantly (p < 0.05) elevated antibody titers, demonstrating the ability of the chimeras to elicit robust humoral immune responses. The integration of bioinformatics-driven epitope prediction with recombinant DNA technology represents a promising and innovative strategy for controlling proliferative enteropathy. This study underscores the value of in silico design strategies for the development of targeted veterinary immunogens and provides a foundation for further research aimed at evaluating protective efficacy under field conditions.