Gel chromatography of serum from mice infected with a virus elevating L-lactate: NAD oxidoreductase activity--an attempt to separate viral and enzymatic activities.

Gel chromatography on Spheron P-500 of mouse serum yielded fractions elevating lactate dehydrogenase activity. The order of elution was viral activity, proteins and lactate dehydrogenase activity. Viral contamination occurred also in certain fractions subjected to repeated gel chromatography in which no proteins were detectable.