Northern cereal mosaic virus, grown in barley plants, was purified from grounding plant mate-rials suspended in 0.1M glycine solution at pH 6.5. Extracted juice was added to active carbon and DEAE cellulose powder as absorption materials for host cell components. The mixture was stirred for one to two minutes and filtered by suction through Celite (Hyflo-Supercel) in a Büchner funnel. The virus was then pelleted by centrifugation at 26, 000g. for one hour The resulting pellet was suspended in the glycine solution and centrifuged on a sucrose density at 41, 000g. for 45 minutes. The virus zone in sucrose density was withdrawn and further purified by density gradient electrophoresis, Viruses were almost completely separated from contaminating plant components by the electrophoresis. When purified preparations of the virus were injected into its vector planthoppers (Laodelphax striatellus) with glass capillaries, a high percentage of survived planthoppers could transmit the virus to barley seedlings. The virus particle was found to be bacilliform and 350 (330-380) nm×68nm in size. The virus was revealed to contain RNA. The lipid fraction extracted with chloroform-methanol (2:1) from a highly purified virus preparation was analyzed by thin layer chromatography. Sterol and phospholipids (phosphatidyl-ethanolamine and possibly phosphatidyl-serine) were detected. Antiserum to the purified virus (128-256 in titer) reacted positively with the semipurified preparations from four isolates of the same virus obtained from the northern and central parts of Japan. No serological differences were found among these four isolates.
Serum samples were collected from a total of 248 horses in Hokkaido during a period of 1965-1971 and examined for hemagglutination-inhibiting (HI) and/or complement-fixing (CF) V and S antibodies against 4 strains of equine and human influenza virus; that is A/Equi-1/Prague/56, A/Equi-2/Miami/63, A/Aichi/2/68 (Hong Kong type), and A/Kumamoto/1/67 (A2 type). The serum samples from 168 horses native to Hokkaido were all negative (<1:8) for each of the virus strains in HI tests. Of them, 129 samples were also proved to be negative (<1:4) for the CF test with equine and Hong Kong virus It was confirmed that there had been no epizootic of influenza among horses in Hokkaido before 1970. In contrast, of 80 horses imported before 1970, 48 (60.0%) had HI antibody against Equi-1, 23 (28.7%) against Equi-2, 14 (21.2%) against Hong Kong virus, and none against A2 virus. When examined by the CF-V test, 42.6% of the horses had antibody against Equi-1, 42.9% against Equi-2, and 9.8% against Hong kong virus. Besides, 63 sera were all negative for the CF-S test. The presence of antibody against Hong Kong virus in the imported horses suggested that this antibody might have been produced by infection (including vaccination) with antigenically related Equi-2 virus. Epizootiological analyses were carried out to clarify the relationship between the history and the presence of cserum antibody against equine influenza in the individual imported horses.
In order to standardize the titer of polio neutralizing antibody determined by different neutralization tests, the International Standard. Poliomyelitis Antisera have been prepared. Since the supply of the sera is limited, an attempt was made to perpared a national standard serum for the use in Japan. As a result, anti-poliovirus serum type 3 was produced from immunized African green monkeys diluted and distributed into ampoules in 1ml amounts, and freezedried. The reconstituted serum was examined for the protein content. The titer of neutralizing antibody was compared between this serum and the International Standard Serum. From the results of these tests, it was concluded that the prepared serum was suitable for the use as the national standard antipoliovirus type 3 serum, since it contained 40 International units per ampoule.