Antigenicity and Immunogenicity of Rotavirus VP6 Protein Expressed on the Surface ofLactococcus lactis

Abstract

Group A rotaviruses are the major etiologic agents of acute gastroenteritis worldwide in children and young animals. Among its structural proteins, VP6 is the most immunogenic and is highly conserved within this group. Lactococcus lactis is a food-grade, Gram-positive, and nonpathogenic lactic acid bacteria that has already been explored as a mucosal delivery system of heterologous antigens. In this work, the nisin-controlled expression system was used to display the VP6 protein at the cell surface of L. lactis. Conditions for optimal gene expression were established by testing different nisin concentrations, cell density at induction, and incubation times after induction. Cytoplasmic and cell wall protein extracts were analyzed by Western blot and surface expression was confirmed by flow cytometry. Both analysis provided evidence that VP6 was efficiently expressed and displayed on the cell surface of L. lactis. Furthermore, the humoral response of mice immunized with recombinant L. lactis was evaluated and the displayed recombinant VP6 protein proved to be immunogenic. In conclusion, this is the first report of displaying VP6 protein on the surface of L. lactis to induce a specific immune response against rotavirus. These results provide the basis for further evaluation of this VP6-displaying L. lactis as a mucosal delivery vector in a mouse model of rotavirus infection.

Immunomodulatory Properties of Bacterium-Like Particles Obtained From Immunobiotic Lactobacilli: Prospects for Their Use as Mucosal Adjuvants

“…Recombinant LAB expressing rotavirus antigens have been evaluated as vaccine candidates (24)(25)(26)(27). L. casei ATCC 393 (24) and L. lactis NZ9000 (25) expressing the major protective antigen VP4 from rotavirus efficiently induced the production of serum IgG and mucosal IgA anti-VP4 antibodies, which also demonstrated neutralizing effects on rotavirus infection.…”

Rotavirus VP6 preparations as a non-replicating vaccine candidates

“…Mice immunized with recombinant VP6 proteins were shown to prime B cells specific for neutralizing epitopes of the VP7 and VP4 proteins [119]. Bacterial vectors expressing RV VP6 proteins were found to be immunogenic in mice [120,121]. In 2007, Dennehy et al [121] have used episomal and integrative E. coli-mycobacterium shuttle vectors to generate recombinant BCG-expressing RV VP6 protein.…”

“…However, expressed recombinant VP6 protein of RV on Lactococcus lactis has proved to induce a RV-specific serum Abs in mice in the absence of any exogenous adjuvant [120]. Moreover, plant-based VP6 vaccine [14,17,18] are reported to efficiently elicit mucosal IgA and serum IgG in vaccinated dams [17,18].…”

Rotavirus VP6 as a potential vaccine candidate

“…These results indicate that parenteral administration of VP6 targeting DEC‐205 can induce protection at the intestinal level at a very low dose, which may be Th1‐type cell dependent . Moreover, an induced specific humoral immune response against RV VP6 has been reported using an expression system displaying RV VP6 protein at the cell surface of Lactococcus lactis . Similar study also described the cell wall‐derived particles (CWDPs) from recombinant L. lactis expressing RV VP6 protein.…”