Encephalomyocarditis (EMC) virus causes lethal
infection of hamsters against which
poly(I) .
poly(C) causes dose-dependent protection. In contrast, no
antiviral effects occur with
poly(I) .
poly(C) against influenza virus
infection of hamsters. Serum from
poly(I) .
poly(C) treated hamsters protects other hamsters against EMC
virus infection with maximum protection with serum removed 3h after
poly(I) .
poly(C) treatment of the donor hamsters. In such assays the factor was found to be inactivated by
trypsin and pH 2 and 56 degrees C for 1 hr. The serum factor did not confer protection against EMC
virus infection of L-929, BHK, Hak or primary hamster embryo cells. The amount of
poly(I) .
poly(C) carried over into serum samples of
poly(I) .
poly(C) treated hamsters was insufficient to account for the
antiviral effects. The
antiviral serum factor is presumed to be a form of
interferon despite the fact that it does not titrate in cell cultures and has a novel set of properties from those which describe known
interferons.