Studies on Certain Viruses Isolated in the Tropics of Africa and South America. Immunological Reactions As Determined by Cross Complement-Fixation Tests
Noninfectious, lipid-extracted, complement-fixing antigens, which were satisfactory for use with specific antisera prepared in guinea pigs and mice, have been made from the brains of mice infected with 27 different viruses or strains of virus. Lipids were extracted either by means of the acetone-ether extraction technique of Casals, or, in the case of 5 viruses, with benzene. There were no failures to secure an antigen when an attempt was made to do so. The sera used in this study were all obtained from guinea pigs and mice, no attempt having been made to examine human sera for the presence of complement-fixing antibody to any of the viruses under investigation. The following viruses gave no cross reactions and are considered to be distinct entities: Bwamba, Bunyamwera, Zika, Wyeomyia, Anopheles A and Anopheles B. Kumba virus is considered to be merely a strain of Semliki virus. Neither of these 2 viruses gave any other cross reactions. West Nile virus in our hands gave no cross reactions, but we have no reason to doubt the validity of cross reactions previously observed by others. Mengo virus gave no cross reactions with any of the other viruses studied, except for a one-way cross with several strains of the GDVII type of mouse encephalomyelitis—that is, by use of Mengo antiserum and GDVII type antigens. Uganda S and yellow fever gave irregular, one-way cross reactions, as did Ntaya and Ilhéus. Four viruses, namely Haemagogus A, Haemagogus B, Leucocelaenus and Sabethes, are shown to be strains of the GDVII type of mouse encephalomyelitis.