Swine Group A rotavirus vaccines: current status, adjuvant strategies, challenges, and future perspectives

Swine Group A rotavirus is one of the primary intestinal pathogens causing severe diarrhea in newborn piglets, with high incidence and mortality resulting in substantial economic losses to the global swine industry. Vaccination, alongside rigorous biosecurity measures, remains the core strategy for controlling porcine Group A rotavirus infection; however, continuous genetic variation via genomic reassortment, point mutations, and diverse G/P genotype combinations drives the constant emergence of new circulating strains that may evade immune protection from existing vaccines. These genetic changes may also give rise to highly pathogenic variants, increasing large-scale outbreak risk. Therefore, developing vaccines that provide stable, broad cross-protection against viral strain diversity is particularly critical. Vaccine adjuvants play a vital role in enhancing and modulating immune responses, broadening protection spectra, and reducing the antigen dose required for protection especially valuable when facing rapidly changing genotypes or limited vaccine antigen supplies. In recent years, advances in adjuvant design and formulation strategies have clearly improved the immunogenicity and duration of protection of swine Group A rotavirus vaccines, as evidenced by significantly reduced diarrhea incidence and viral shedding intensity in vaccinated piglets. Building on an overview of the current status, advantages, and challenges of different porcine Group A rotavirus vaccine types, this review focuses on the mechanisms of action, application advantages, existing limitations, and methodological strategies of adjuvants. It further analyzes the potential contribution of adjuvant strategies to developing a universal porcine rotavirus vaccine capable of broad, long-lasting cross-protection. Finally, this review identifies key unresolved scientific questions and critical knowledge gaps in the field, with the aim of guiding future research priorities.