A Novel Recombinant Virus-Like Particles Displaying B and T Cell Epitopes of Japanese Encephalitis Virus Offers Protective Immunity in Mice and Guinea Pigs

Virus-like particles (VLPs) are non-replicative vectors for the delivery of heterologous epitopes and are considered one of the most potent inducers of cellular and humoral immune responses in mice and guinea pigs. In the present study, VLP-JEVe was constructed by the insertion of six Japanese encephalitis virus (JEV) envelope protein epitopes into different surface loop regions of PPV VP2 by the substitution of specific amino acid sequences without altering the assembly of the virus; subsequently, the protective efficacy of this VLP-JEVe was evaluated against JEV challenge in mice and guinea pigs. Mice immunized with the VLP-JEVe antigen developed high titers of neutralizing antibodies and 100% protection against lethal JEV challenge. The neutralizing and hemagglutination inhibition (HI) antibody responses were also induced in guinea pigs vaccinated with VLP-JEVe. In addition, immunization with VLP-JEVe in mice induced effective neutralizing antibodies and protective immunity against PPV (porcine parvovirus) challenge in guinea pigs. These studies suggest that VLP-JEVe produced as described here could be a potential candidate for vaccine development.

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Stable High-Producer Cell Clone Expressing Virus-Like Particles of the Japanese Encephalitis Virus E Protein for a Second-Generation Subunit Vaccine

Journal of Virology ◽

10.1128/jvi.77.16.8745-8755.2003 ◽

2003 ◽

Vol 77 (16) ◽

pp. 8745-8755 ◽

Cited By ~ 36

Author(s):

Asato Kojima ◽

Atsushi Yasuda ◽

Hideki Asanuma ◽

Toyokazu Ishikawa ◽

Akihisa Takamizawa ◽

...

Keyword(s):

Japanese Encephalitis Virus ◽

Japanese Encephalitis ◽

Neutralizing Antibodies ◽

Second Generation ◽

Cell Clone ◽

Encephalitis Virus ◽

Rabbit Kidney ◽

Enzyme Linked Immunosorbent Assay ◽

Dilution Method ◽

Virus Like Particles

ABSTRACT We produced and characterized a cell clone (J12#26 cells) that stably expresses Japanese encephalitis virus (JEV) cDNA, J12, which encodes the viral signal peptide, premembrane (prM), and envelope (E) proteins (amino acid positions 105 to 794). Rabbit kidney-derived RK13 cells were transfected with a J12 expression plasmid, selected by resistance to marker antibiotics, and cloned by two cycles of a limiting-dilution method in the presence of antibiotics, a procedure that prevents the successful generation of E-producing cell clones. J12#26 cells secreted virus-like particles containing the authentic E antigen (E-VLP) into the culture medium in a huge enzyme-linked immunosorbent assay-equivalent amount (2.5 μg per 104 cells) to the internationally licensed JE vaccine JE-VAX. E-VLP production was stable after multiple cell passages and persisted over 1 year with 100% expressing cells without detectable cell fusion, apoptosis, or cell death, but was suspended when the cells grew to 100% confluency and contact inhibition occurred. Mice immunized with the purified J12#26 E-antigen without adjuvant developed high titers of neutralizing antibodies for at least 7 months and 100% protection against intraperitoneal challenge with 5 × 106 PFU of JEV when examined according to the JE vaccine standardization protocol. These results suggest that the recombinant E-VLP antigen produced by the J12#26 cell clone is an effective, safe, and low-cost second-generation subunit JE vaccine.

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A Japanese Encephalitis Virus Peptide Present on Johnson Grass Mosaic Virus-Like Particles Induces Virus-Neutralizing Antibodies and Protects Mice against Lethal Challenge

Journal of Virology ◽

10.1128/jvi.77.6.3487-3494.2003 ◽

2003 ◽

Vol 77 (6) ◽

pp. 3487-3494 ◽

Cited By ~ 45

Author(s):

Manisha Saini ◽

Sudhanshu Vrati

Keyword(s):

Japanese Encephalitis Virus ◽

Mosaic Virus ◽

Japanese Encephalitis ◽

Neutralizing Antibodies ◽

Recombinant Dna ◽

Gradient Centrifugation ◽

Encephalitis Virus ◽

Virus Like Particles ◽

E Protein ◽

Johnson Grass

ABSTRACT Protection against Japanese encephalitis virus (JEV) is antibody dependent, and neutralizing antibodies alone are sufficient to impart protection. Thus, we are aiming to develop a peptide-based vaccine against JEV by identifying JEV peptide sequences that could induce virus-neutralizing antibodies. Previously, we have synthesized large amounts of Johnson grass mosaic virus (JGMV) coat protein (CP) in Escherichia coli and have shown that it autoassembled to form virus-like particles (VLPs). The envelope (E) protein of JEV contains the virus-neutralization epitopes. Four peptides from different locations within JEV E protein were chosen, and these were fused to JGMV CP by recombinant DNA methods. The fusion protein autoassembled to form VLPs that could be purified by sucrose gradient centrifugation. Immunization of mice with the recombinant VLPs containing JEV peptide sequences induced anti-peptide and anti-JEV antibodies. A 27-amino-acid peptide containing amino acids 373 to 399 from JEV E protein, present on JGMV VLPs, induced virus-neutralizing antibodies. Importantly, these antibodies were obtained without the use of an adjuvant. The immunized mice showed significant protection against a lethal JEV challenge.

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