Elevated gamma-globulin and increased antibody production in mice infected with lactic dehydrogenase virus

Studies on the mechanism of action of Riley virus. IV. The reticuloendothelial system and impaired plasma enzyme clearance in infected mice

The plasma clearance of intravenously injected rabbit muscle LDH was studied. In normal mice the clearance followed a biphasic exponential curve comprising an initial fast and subsequent slow phase. Riley virus-infected mice showed only the slow phase of enzyme clearance. The change from fast to slow clearance rate in normal mice appeared to depend upon the level of plasma enzyme activity rather than on the amount of enzyme cleared. Treatment of mice with RES-blocking agents (cholesterol oleate and carbon) inhibited the fast clearance phase, whereas an RES-stimulating agent (stilbestrol) caused an accelerated rate of enzyme clearance. Riley virus infection was found to inhibit the clearance of phosphoglucose isomerase, but had no effect on the clearance of alanine transaminase. The activity of the former enzyme is raised in the plasma of infected mice, whereas the activity of the latter enzyme is unaltered.

Passive haemagglutination for estimation of early and late anti-human gamma-globulin antibodies

The influence of various concentrations of human γ-globulin (HGG) employed to sensitize tanned sheep erythrocytes on haemagglutination titres with various early and late mouse and rabbit antisera to HGG has been studied. The concentration of HGG employed to sensitize tanned erythrocytes which gives the highest haemagglutination titres with early, mercaptoethanol-sensitive antibodies was not optimal for obtaining highest haemagglutination titres with late, mercaptoethanol-insensitive antibodies. Similar results were obtained with heavy and light sucrose gradient ultracentrifugation fractions of a late and early rabbit antiserum. These findings may account for past discrepancies and should be considered when employing the haemagglutination test to detect early and late antibodies.

Infectious virus-antibody complex in the blood of chronically infected mice

If viremic sera from mice chronically infected with lactic dehydrogenase virus (LDV) were first treated with ether or ultraviolet light to inactivate the infectious virus, neutralizing antibody could be demonstrated. Significant amounts of antibody, however, were not detected until the mice had been infected for about 2(1/2) months and its presence did not result in the elimination of the chronic viremia. Virus isolated from sera containing neutralizing antibody was found to be relatively resistant to neutralization by anti-LDV. Further studies revealed that the resistant virus existed in the form of an infectious virus-antibody complex (sensitized virus). The presence of such a complex was demonstrated by the fact that the virus fraction which persisted after in vivo or in vitro exposure to mouse anti-LDV was readily neutralized by goat anti-mouse sera or goat anti-mouse gamma-globulin, whereas virus that had not been previously exposed to mouse anti-LDV was completely resistant to neutralization by goat anti-mouse sera. These findings suggest that (a) sensitization may play an important role in the resistance and susceptibility of a virus to neutralization by antiviral antibody, and (b) an anti-gamma-globulin may prove useful in neutralizing the resistant fraction and in demonstrating otherwise undetectable antiviral antibody.