
744. studies on protein and nucleic acid metabolism in virus-in-
fected mammalian cells.  the formation of a virus-specific
antigen in krebs ii ascites-tumour cells infected with ence-
phalomyocarditis virus
krebs ii mouse ascites-tumor cells infected
with encephalomyocarditis virus were
found to contain, in addition to mature virus,
a virus-specific protein antigen.  an
assay, based on the ability of this antigen
to block the neutralization of purified virus
by its specific antiserum, was developed.
this antigen was present both in the cul-
ture fluid 17 hr. after the infection of cells
with virus and intracellularly, where its
titer increased at a time when viral capsid
protein was being synthesized.  within the
cell, it was mostly localized in the soluble
cell sap.  in contrast with virus, the anti-
gen did not agglutinate sheep erythrocytes,
and its immunological properties were
destroyed by digestion with trypsin.  ribonucleic
acid was not detected in concentrat-
ed preparations of the antigen, nor was the titer
of antigen affected by ribonuclease.
the antigen had a sedimentation coefficient (20 )
of approx. 14s, and its diffusion co-
efficient, determined by the method of allison and
humphrey (1960), was 3.2 x 10-7
sq. cm. sec.-1.  the particle weight of the antigen
was hence 420,000   40,000.  the
capsid protein from purified encephalomyocarditis
virus could be degraded by treat-
ment with ethanolamine into a protein of sedimentation
coefficient (20 ) of approx. 4s.
the 14s antigen, when similarly treated, yielded
a protein of similar size.  however,
no such smaller antigen was detected in virus-infected
cells.  it is concluded that the
non-hemagglutinating antigen represents a polymeric
form of the basic viral capsid-
protein molecule and that it is synthesized in the
cytoplasm of infected cells.  it may
be either an intermediate or a by-product in the
process of viral capsid-protein syn-
thesis.
