Antigenic and Genetic Variations among Japanese Encephalitis Virus Strains Belonging to Genotype 1

Abstract

Hyperimmune antisera against four Japanese encephalitis (JE) virus strains, ThCMAr4492 and ThCMAr6793 from Thailand and Nakayama and JaGAr01 from Japan, were used to analyze the antigenic relationships among 12 Thai strains belonging to genotype 1, and two Japanese strains and one Chinese strain belonging to genotype 3. The antiserum for ThCMAr6793 significantly neutralized nine of the 12 Thai strains, none of which was significantly neutralized by antisera for the Nakayama and JaGAr01 strains. The antiserum for ThCMAr4492 neutralized only its homologous strain; therefore, ThCMAr4492 was antigenically different from all other strains. Two Thai strains (Subin and KE-093/83) were significantly less neutralized by all four of the antisera tested. In the deduced amino-acid sequence of the E protein, the 12 Thai strains revealed 100 to 98.2 % identity among them and 90.0 to 98.8 % identity with the published strains, respectively. Among significant amino-acid substitutions, three residues at positions E-222, E-327 and E-366 were shared by all of the Thai strains, whereas residues at E-89, E-123, E-131, E-178, E-293, E-351 and E-373 seemed to be strain-specific. The amino acids at positions E-178, E-327, E-351, E-373 and E-366 are found either in the peptides with functional T-helper cell epitopes or in the ectodomain of the E protein of other flaviviruses. These amino acids may therefore be responsible for determining the antigenic heterogeneity of these strains.

Humanized Monoclonal Antibodies Derived from Chimpanzee Fabs Protect against Japanese Encephalitis Virus In Vitro and In Vivo

“…It is estimated that JEV causes 35,000 to 50,000 cases of encephalitis, including 10,000 deaths and as many neurologic sequelae, each year (61). Although only one JEV serotype is known to exist, cross-neutralization experiments have demonstrated antigenic differences among JEV strains (1). Phylogenic studies have identified five JEV genotypes, four of which are presently recognized (5,55,62).…”

Evaluation of Chimeric Japanese Encephalitis and Dengue Viruses for Use in Diagnostic Plaque Reduction Neutralization Tests

“…1). JEV Nakayama, isolated in Japan in 1935, and SA14-14-2, an attenuated strain of SA-14 which was isolated in China in 1954, are both grouped in JEV genotype III based on phylogenetic analysis (1,2,12,22,38,39,51,52). Historically, isolates from Vietnam have also clustered into genotype III, with slightly higher homology to SA-14 than to Nakayama.…”

Prevention and Control of Japanese Encephalitis Viruses: A Challenged Issue

“…According to the continue public health impact of JE in Thailand, it has led to effort in childhood immunization and vaccine production in 1985. It was demonstrated by hemagglutination inhibition and neutralization assay that there are definitive antigenic differences among JEV Thai strain and between Thai strains and the standard subtypes, Nakayama and Beijing strains (Ali et al, 1995;Ali & Igarashi, 1997). Most of JEV isolated in Thailand are belonging to genotype I, while some belonging to genotype II, which strains Nakayama and Beijing are belonging to genotype III (Ali & Igarashi, 1997).…”

“…It was demonstrated by hemagglutination inhibition and neutralization assay that there are definitive antigenic differences among JEV Thai strain and between Thai strains and the standard subtypes, Nakayama and Beijing strains (Ali et al, 1995;Ali & Igarashi, 1997). Most of JEV isolated in Thailand are belonging to genotype I, while some belonging to genotype II, which strains Nakayama and Beijing are belonging to genotype III (Ali & Igarashi, 1997). The monovalent vaccine derived from JEV strain Nakayama or bivalent vaccine consisting of Nakayama and Beijing-1 strains provide 91% protective efficiency in either protocol in Thai children.…”