GITRL as a genetic adjuvant enhances enterovirus 71 VP1 DNA vaccine immunogenicity

Recent progress and advances towards developing enterovirus 71 vaccines for effective protection against human hand, foot and mouth disease (HFMD)

The main pathogen causing severe and neurotrophic hand, foot and mouth disease (HFMD) is enterovirus A71 (EV71). EV71 infection is among the major cause of serious public health burden and economic loss especially in the Asia-pacific region. Yet, no specific anti-viral treatment against this life-threatening infection is currently available. Thus, the best way to control EV71 infection is by vaccination with an effective and safe vaccine. Several strategies are being employed to develop vaccines against EV71. These include conventional and modern recombinant vaccine strategies. Conventional vaccines such as inactivated EV71 vaccines are the most studied and advanced vaccines against HFMD. Recombinant HFMD vaccines developed based on the recombinant DNA technology have been employed but are mostly at early or late preclinical development stage. In this article, we discuss the recent progress and advances in modern recombinant strategies of EV71 vaccine development including subunit, VLP, epitope-based, DNA, and vector-based vaccines, as well as conventional approaches, focusing on their various prospects, advantages and disadvantages.

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.