Recombinant lactococcus lactis secreting viral protein 1 of enterovirus 71 and its immunogenicity in mice.

Objective: To construct recombinant Lactococcus lactis (L. lactis) expressing viral protein 1 (VP1) of enterovirus 71 (EV71) and evaluate its immunogenicity to be used as an oral vaccine in BALB/c mice.

Results: Recombinant L. lactis competent in secreting VP1 (~ 30 kDa) into the extracellular environment with the aid of the signal peptide Usp45 was produced. Enzyme-linked immunosorbent assay showed that significant VP1-specific antibody response including the production of both serum IgG and fecal IgA (p < 0.05) was elicited in BALB/c mice upon oral immunization with recombinant L. lactis. Moreover, in contrast to negative control, recombinant L. lactis induced adequate neutralizing antibodies in mouse sera (p < 0.05) as demonstrated in virus neutralization assay, whereas the presence of neutralizing antibodies in fecal samples was obvious but not significant (p > 0.05).

Conclusions: Recombinant L. lactis expressing VP1 of EV71 has the potential to be used as an oral vaccine candidate. The findings may provide some preliminary evidences for further development of effective and needle-free EV71 vaccines.