ON THE GROWTH OF VENEZUELAN EQUINE ENCEPHALOMYELITIS VIRUS AND CYTOPATHOGENIC EFFECT OF THE VIRUS IN EMBRYO- AND TUMOR-TISSUE CULTURES FROM VARIOUS KINDS OF ANIMALS

A remarkable progress has been made on the virus growth, the cytopathogenic effect and the plaque count of various kinds of animal viruses in tissue culture since those of poliomyelitis viruses were described by Enders.<br>The attempt was made by author to investigate the growth curve of Venezuelan encephalomyelitis in tissue culture by using human, pig, cattle, guinea-pig and chicken-embryos in order to make clear the relationship between the virus and the host cell compared with the cultivation of poliomyelitis virus in chicken embryo tissue. The cultivation of the virus was carried out through stational method in the medium consisting of Earle's solution 45%, pig-embryo extract 10% and human ascitic fluid 45%.<br>The results were obtained as follows:<br>1. Venezuelan equine encephalomyelitis virus is grown in tissue culture by using embryo mentioned above, passed from generation to generation and produces a cytopathogenic effect which is recognized in human embryo tissue culture in each generation three days later, in pig embryo tissue culture in each generation two days later, in chicken embryo tissue culture in the first and the second generations two days later and in the third generation three days later, and in cattle embryo tissue culture two days after the inoculation of the virus.<br>2. The growth of the virus was observed prior to the appearance of cytopathogenic effect in embryo tissue cultures.<br>3. The cytopathogenic effect of the viruses was found not on the epithelial cell but on the fibroblast following the degeneration of its nucleous in embryo tissue culture.<br>4. Contrary to embryo tissue culture the virus was not markedly grown and produced little or no cytopathogenic effect in tumor tissue cultures using mouse fructose sarcoma and both hard and soft rat rhodamine sarcomas.<br>5. The cytopathogenic effect of the virus was inhibited specifically by homologous immune rabbit serum but not by heterogenous equine encephalitis immune sera.<br>From the basic experiment the neutralization test is available to determine the potency of the test serum by tissue culture. The neutralization lndex obtained by the test of tissue culture was much higher than those by the intracerebral inoculation in mice.<br>6. Neither growth nor cytopathogenic effect of poliomyelitis I type virus (Brunhilde strain) was observed in chicken embryo tissue culture.