The hydatid cyst fluid protein EgAgB8/1 demonstrates potent immunogenicity by eliciting robust humoral and cellular immune responses in mice

BACKGROUND: Cystic echinococcosis (CE), a neglected zoonotic disease caused by the larval stage of Echinococcus granulosus, requires effective vaccine strategies for sustainable control. This study evaluated the immunogenic profiles of two antigenic targets: EgAgB8/1, a dominant immunogenic component of hydatid cyst fluid, and Eg-01883, a protoscolex-specific antigen identified through bioinformatic screening. METHODOLOGY/PRINCIPAL FINDINGS: E. granulosus strains were isolated from infected dogs for genomic DNA extraction. Recombinant proteins rEgAgB8/1 and rEg-01883 were expressed in E. coli, purified, and validated by SDS-PAGE and western blot. Initial protein microarray screening identified rEgAgB8/1 as exhibiting markedly higher immunoreactivity with cystic echinococcosis (CE) patient sera compared to the minimally reactive Eg-01883. Based on this finding, subsequent investigation focused on rEgAgB8/1 using a BALB/c mouse immunization model. The recombinant protein elicited potent humoral immunity, with antigen-specific IgG titers reaching 1:16,000, and stimulated significant lymphocyte proliferation. Immunized mouse sera specifically recognized native EgAgB8/1 in hydatid crude antigen preparations, confirming natural antigenicity. Flow cytometric analysis demonstrated that rEgAgB8/1 immunization significantly expanded splenic plasmablasts, memory B cells, and T follicular helper cells. Furthermore, it enhanced IFN-γ production in both CD4⁺ and CD8 ⁺ T cells while maintaining baseline IL-10 ⁺ T cell frequencies, and induced robust T cell memory responses. Statistical analyses were performed using Student's t-test for comparative evaluation. CONCLUSIONS: These findings establish rEgAgB8/1 as a highly immunogenic antigen capable of eliciting a cellular immune response characterized by dominant IFN-γ production without concomitant IL-10 elevation, alongside durable humoral responses in mice. The comprehensive immunogenicity profile supports further research into its immunological potential against cystic echinococcosis.