Antigenic Analysis of Japanese Encephalitis Virus Using Monoclonal Antibodies

Antigenic comparison of 27 strains of Japanese encephalitis virus (JEV) was carried out using hemagglutination inhibition (HI) technique with monoclonal antibodies against Nakayama-RFVL strain. Twenty-four JEV strains were isolated from various parts of Japan, and 3 from Singapore, Thailand and Sri Lanka. These strains were isolated from different hosts between 1935 and 1979. Antigens for the test were obtained from suckling mouse brains by the sucrose-acetone method. The hybrid cells were produced by fusing P3X63Ag 8.653 mouse myeloma cell line with spleen cells from BALB/c mice immunized with JEV Nakayama-RFVL strain. According to the HI test against the 5 species-specific monoclonal antibodies, the 27 JEV strains are classified serologically as follows: I-1. Nakayama-RFVL and Nakayama-Yoken strains. I-2. Nakayama-Yakken strain. II. Kalinina, G-1 late, JaGAr 01 and JaGAr 02 strains. III-1. Sekiya, Mochizuki, Nishizono, JaFAr 401465, JaFS 01, Hatano 65, Kamiyama, Sasazaki, Mie 44-1, Fukuoka 7101, Fukuoka 7202, Fukuoka 7309, Fukuoka 7311, Fukuoka 7452, Fukuoka 7463, Fukuoka 7506, Kumamoto 80679 and Chiang Mai strains. III-2. 691004 strain. IV. Muar strain. Although the Nakayama-Yakken strain was derived from the same origin as the Nakayama-RFVL and Nakayama-Yoken strains, it is a mutant strain which had missed out the Nakayama strain-specific antigen.There are significant antigenic differences between the Nakayama strain and the JaGAr 01 strain and the recently isolated strains. NARMA 13 reacted with almost the same titer against the 26 JEV strains as the homologous (Nakayama-RFVL) strain. On the other hand, NARMA 5 only reacted against the Nakayama-RFVL and Nakayama-Yoken strains. The former is characteristic of JEV species-specificity and the latter of Nakayama strain-specificity.