SOME STATISTICAL OBSERVATIONS ON A CO-OPERATIVE STUDY OF HUMAN PULMONARY PATHOLOGY

Comment.-A factor inhibiting CPE and probably multiplication of several viral strains has been demonstrated in culture fluids of human renal cells infected with a chick embryo adapted strain of Type II poliovirus. The inhibitor can be separated from infective virus and is not inactivated in the presence of homologous antiserum. In certain respects this inhibitor is comparable to "Interferon," a factor appearing in chick embryo tissues exposed to influenza virus.8 That an inhibitor analogous to that described here may represent an essential determinant in chronic cell infection in vitro is suggested by the evidence presented. It is possible that an analogous factor may be produced in vivo in areas of infection. If so, it might play a role in the mechanisms of resistance, now largely unknown, that are operative during the acute stage of viral disease. Summary.-Medium from human kidney tissue culture cells exposed to a strain of avirulent chick embryo-adapted Type II poliovirus inhibits the infection of human amnion and renal cells by homotypic and heterotypic poliovirus as well as other unrelated viruses. This property does not appear to be associated with infective virus or specific viral antigen.