Immune Responses to Orally Administered Recombinant Lactococcus lactis Expressing Multi-Epitope Proteins Targeting M Cells of Foot-and-Mouth Disease Virus.

Zhongwang Zhang,Jiahao Li,Li Pan,Jianliang Lv,Zhongyuan Ma,Fudong Zhang,Xian Li

doi:10.3390/v13102036

Abstract

Foot and mouth disease virus (FMDV), whose transmission occurs through mucosal surfaces, can also be transmitted through aerosols, direct contact, and pollutants. Therefore, mucosal immunity can efficiently inhibit viral colonization. Since vaccine material delivery into immune sites is important for efficient oral mucosal vaccination, the M cell-targeting approach is important for effective vaccination given M cells are vital for luminal antigen influx into the mucosal lymph tissues. In this study, we coupled M cell-targeting ligand Co1 to multi-epitope TB1 of FMDV to obtain TB1-Co1 in order to improve delivery efficiency of the multi-epitope protein antigen TB1. Lactococcus lactis (L. lactis) was engineered to express heterologous antigens for applications as vaccine vehicles with the ability to elicit mucosal as well as systemic immune responses. We successfully constructed L. lactis (recombinant) with the ability to express multi-epitope antigen proteins (TB1 and TB1-Co1) of the FMDV serotype A (named L. lactis-TB1 and L. lactis-TB1-Co1). Then, we investigated the immunogenic potential of the constructed recombinant L. lactis in mice and guinea pigs. Orally administered L. lactis-TB1 as well as L. lactis-TB1-Co1 in mice effectively induced mucosal secretory IgA (SIgA) and IgG secretion, development of a strong cell-mediated immune reactions, substantial T lymphocyte proliferation in the spleen, and upregulated IL-2, IFN-γ, IL-10, and IL-5 levels. Orally administered ligand-conjugated TB1 promoted specific IgG as well as SIgA responses in systemic and mucosal surfaces, respectively, when compared to orally administered TB1 alone. Then, guinea pigs were orally vaccinated with L. lactis-TB1-Co1 plus adjuvant CpG-ODN at three different doses, L. lactis-TB1-Co1, and PBS. Animals that had been immunized with L. lactis-TB1-Co1 plus adjuvant CpG-ODN and L. lactis-TB1-Co1 developed elevated antigen-specific serum IgG, IgA, neutralizing antibody, and mucosal SIgA levels, when compared to control groups. Particularly, in mice, L. lactis-TB1-Co1 exhibited excellent immune effects than L. lactis-TB1. Therefore, L. lactis-TB1-Co1 can induce elevations in mucosal as well as systemic immune reactions, and to a certain extent, provide protection against FMDV. In conclusion, M cell-targeting approaches can be employed in the development of effective oral mucosa vaccines for FMDV.

Highlights

Foot-and-mouth disease (FMD), a clinical acute vesicular and extremely contagious infection, is transmissible among clove hoofed animals [1]. It is caused by the foot-andmouth disease virus (FMDV), which belong to the Aphthovirus genus and Picornaviridae family
Recombinant proteins were expressed as soluble proteins in L. lactis NZ9000 using the nisin-controlled expression (NICE)
FMDV infections occur at mucosal surfaces, mucosal immunization using specific multi-epitope antigens can protect against infections

Summary

Introduction

Foot-and-mouth disease (FMD), a clinical acute vesicular and extremely contagious infection, is transmissible among clove hoofed animals [1]. It is caused by the foot-andmouth disease virus (FMDV), which belong to the Aphthovirus genus and Picornaviridae family. From 2009 to 2010, many outbreaks that are closely associated with the above strain have been reported in other regions of China. In 2013, A/GDMM/CHA/2013 FMDV, a new strain, occurred in Maoming, Guangdong, China. Inactivated vaccines play a fundamental role in controlling FMD outbreaks, especially in developing countries [4]. Chemically inactivated vaccines provide good protection, they have various limitations, such as their potential for escape of a live virus during production and application and their high production costs [5]. The technology used in multi-epitope proteins as well as their application as vaccines has been widely evaluated [6,7]

Methods

Results

Conclusion