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

Introduction: Polyvalent hyperimmune sera are widely used for emergency passive immunoprophylaxis; however, controlled experimental evidence supporting their safety and preventive efficacy remains limited. Methods: application. 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.