Sterility, safety, and preventive efficacy of three polyvalent hyperimmune sera against bacterial infection in a white mouse challenge model.

Abstract

INTRODUCTION: Polyvalent hyperimmune sera are widely used for emergency passive immunoprophylaxis; however, controlled experimental evidence supporting their safety and preventive efficacy remains limited. METHODS: In this study, three polyantigenic hyperimmune sera were evaluated using a standardized white mouse bacterial challenge model. Sera were generated through stepwise immunization of donor animals with monovalent and polyvalent antigenic formulations targeting enteric and respiratory pathogens. Sterility and safety were assessed prior toapplication. Preventive efficacy was evaluated following subcutaneous administration of sera 24 h before experimental infection with enteric bacterial pathogens. RESULTS: Serological characterization confirmed robust virus- and bacteria-specific humoral responses in donor animals, with end-point antibody titers reaching up to 1:2560 in serum preparations containing viral antigens. All tested sera were sterile and well tolerated, with no adverse clinical effects observed during the monitoring period. Prophylactic administration led to a marked increase in survival compared with untreated controls across multiple bacterial challenge models, with absolute risk reduction values ranging from 40 to 100%. In contrast, native serum collected prior to immunization provided only partial or no protection. DISCUSSION: Overall, these findings provide controlled experimental evidence demonstrating the safety, immunogenicity, and reproducible preventive efficacy of polyvalent hyperimmune sera in a murine bacterial infection model, supporting their consideration as candidate immunobiological agents for passive protection against bacterial infections under controlled experimental conditions.