Sachiko Matsuo

Finer mapping of neutralizing epitope(s) on the C-terminal of Japanese encephalitis virus E-protein expressed in recombinant Escherichia coli system

In order to localize denaturation-resistant neutralizing epitope(s) in the C-terminal 180 amino acids of Japanese encephalitis (JE) virus E-protein, four recombinant clones encoding different or overlapping nucleotide sequences were constructed by PCR from a recombinant plasmid pS22. The amplified fragments were cloned into PCR 1000 vector, and then transferred into Escherichia coli expression vector pRIT2T. The inserted genes were expressed as fusion proteins with protein-A and examined for their antigenicity and immunogenicity by Western blotting and mouse immunization, respectively. Among the four recombinant fusion proteins, the highest neutralizing antibody titre was obtained by the one expressed by the recombinant clone pRIT2T-B3, which carried the coding sequence of amino acid number 373-399 of JE virus E protein. The results indicated that this short region of 27 amino acids sequence near the C-terminal of JE virus E protein possesses neutralizing epitope(s). These data should assist in the design of an efficient subunit vaccine against JE virus infection in future.

Japanese Encephalitis Virus Fusion Protein with Protein A Expressed in Escherichia coli Confers Protective Immunity in Mice

A complementary DNA (cDNA) that codes C‐terminal, one‐third of envelope glycoprotein (E) and N‐terminal 65 amino acids of NS1 protein of Japanese encephalitis (JE) virus was inserted into Escherichia coli expression vector pRIT2T. The inserted gene was expressed as a fusion protein with protein A, and the expressed protein was intraperitoneally injected into mice. The immunized mice produced anti‐JE antibodies measured by the hemagglutination‐inhibition and neutralization tests as well as ELISA and were protected from the lethal challenge of JE virus by intraperitoneal inoculation.

Some properties of temperature-sensitive mutant of rubella virus defective in the induction of interference to Newcastle disease virus

Abstract Replication of a temperature-sensitive mutant of rubella virus, ts-201, occurred normally at 33° but was inhibited at 3.85° in BSC-1 cells. Temperature sensitivity of the mutant did not appear to be due to the failure of adsorption of the virus to the cells nor due to defects in structural components of virion. The mutant, however, was shown to be defective in inducing viral RNA synthesis, viral antigen(s) synthesis and interference to Newcastle diseases virus. Temperature-shift experiments on the subsequent replication of the virus and on the induction of interference suggested that the induction of interference is an early viral gene function and closely related to subsequent replication of the virus.