Uganda S virus

(1) The isolation of what is believed to be a hitherto undescribed virus is recorded. Although the origin of the agent is uncertain, the evidence which has been presented indicates that it was isolated from one of the following species of mosquitoes: Aedes (F.) longipalpis, A. (F.) ingrami, A. (A.) natronius. (2) Studies on the immunological relationship of Uganda S virus to other viruses are presented elsewhere (DICK, to be published); they indicate that Uganda S virus is not identical with any previously described virus. Neutralization tests have demonstrated antibody to Uganda S virus in high titre in 5.8 per cent. of sera from residents of Western Uganda and in the serum of one of six wild monkeys. (3) The pathogenicity of Uganda S virus for mice, cotton-rats, guineapigs and for rhesus, grivet and redtail monkeys is described. The agent is highly neurotropic for mice only and has produced no clinical signs of infection in the other animals tested. Monkeys vary in their susceptibility to Uganda S virus as evidenced by the circulation of virus and development of antibody. (4) Uganda S virus would appear to have a particle size of between 75 and 112 mμ. This estimate is subject to revision when other methods of size estimation have been applied. It would appear to be one of the more unstable viruses when in suspensions, but is readily preserved by desiccation. No studies have as yet been made on the susceptibility of Uganda S virus to chemicals, nor have attempts been made to cultivate it in chick embryos. (5) Nothing is known of the natural history of the virus or of the disease, if any, which it produces in man or animals.