Increased Plasma Isomerase and Transaminase Activity in Mice infected with Lactic Dehydrogenase-elevating Virus

Abstract

MICE bearing large tumours or with advanced leukæmia have a raised plasma lactic dehydrogenase (LDH) activity which may be wholly due to the presence of the neoplastic cells or in part due to a virus which is frequently found contaminating transplantable tumours and virus preparations derived from mouse tissues^1,2. This enzyme-elevating virus (Riley virus) causes a permanent viræmia in the infected mice, and the 5–10-fold increase in the plasma LDH activity which it produces persists indefinitely. The site of virus replication and the mechanism by which the plasma LDH activity is elevated have not been determined, but the plasma LDH activity does not appear to be a property of the virus particle, as the virus titre and the LDH activity of the plasma are not correlated³. It would seem that the increased plasma LDH activity must come from cells damaged or altered by the virus, and so it seemed of interest to know if other plasma enzymes were affected by this enzyme elevating virus.