Immunization with PLGA-encapsulated recombinant staphylococcal enterotoxin C confers protection against intramammary Staphylococcus aureus challenge in a murine mastitis model.

Authors

Desh Deepak, Preena Prasanna, Radhika Vaidya, Syed Atif Ali, Nongthombam Boby, Banaja Kanta Pati, Ujjwal Kumar De, Med Ram Verma, Monalisa Sahoo, Pallab Chaudhury, Reena Mukherjee

Published in

Antonie van Leeuwenhoek. Volume 119. Issue 9. Aug 14, 2026. Epub Aug 14, 2026.

Abstract

Mastitis caused by Staphylococcus aureus remains a significant challenge to control due to increasing antimicrobial resistance and the limited efficacy of existing vaccines. Staphylococcal enterotoxin C (SEC) is a critical virulence factor and a highly immunogenic determinant in S. aureus strains frequently isolated from bovine mastitis cases. In this study, we evaluated the immunogenicity and protective efficacy of recombinant SEC (rSEC) encapsulated within poly(lactide-co-glycolide) microparticles (PLGA-rSEC) using a murine mastitis model. Immunization with PLGA-rSEC induced significantly higher serum IgG responses (OD₄₉₂) compared with bacterin, non-encapsulated rSEC and control groups (p < 0.05). Following intramammary challenge with S. aureus, mice immunized with PLGA-rSEC showed a marked reduction in mammary gland bacterial load, resulting in a 3.15 log₁₀ CFU/gland reduction. This protective efficacy was significantly superior to that of the traditional bacterin group (2.23 log₁₀ CFU/gland; p < 0.05). Furthermore, PLGA-rSEC-immunized mice exhibited attenuated inflammatory responses, characterized by lower serum C-reactive protein (CRP) levels and a rapid reduction in serum IL-10 concentrations post-challenge. Histopathological analysis confirmed the preservation of mammary gland architecture with minimal inflammatory cell infiltration in the PLGA-rSEC group, contrasting with the severe necrosis and abscess formation observed in control groups. Overall, PLGA-encapsulated rSEC elicited a robust humoral immune response and conferred significant protection against intramammary S. aureus challenge. These findings suggest that PLGA-rSEC is a promising subunit vaccine candidate for the prevention of S. aureus-associated bovine mastitis, offering improved protective efficacy compared with conventional vaccine formulations.

PMID:
42599583
Bibliographic data and abstract were imported from PubMed on 15 Aug 2026.

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