The Nature of Antibody in Swine Naturally Infected with Japanese Encephalitis Virus

Abstract

Summary When serum specimens of pigs obtained weekly from a slaughterhouse throughout the summer of 1965 were tested for their HI activity against J.E. virus, an abrupt change was seen from 4% positive in the second week to 46% positive in the third week. By the fourth week, 90% were positive. When the 2-ME sensitivity HI activity of these sera was tested, almost 100% of the specimens obtained through these 3 weeks contained 2-ME-sensitive antibody. However, sensitivity to 2-ME was reduced to 70% in the first week of September, to 44% in the second week, and after the fourth week, none of the tested serum specimens was sensitive. Evidently, 2-ME-sensitive antibody appeared before the 2-ME-resistant antibody and the detection of 2-ME-sensitive antibody against J.E. virus in the early summer gave a reliable basis for prediction of the outbreak among human beings later in that year.