Protracted circulating lifetimes of mannose-terminated glycoproteins and aggregated albumin in mice infected with LDH-elevating virus.

Several macromolecular homeostasis-regulating mechanisms were tested for functional integrities in mice during acute and early chronic phases of infection with lactic dehydrogenase-elevating virus (LDV). Fractional catabolic rates of carbodiimide-aggregated albumin and immunoglobulin G were studied to evaluate glomerular filtration and hepatic Kupffer cell phagocytic activities. Several glycoproteins (fetuin, IgG antibodies, and ovalbumin) were also compared with their deglycosylated counterparts for fractional catabolic rates and organ distributions as a basis for evaluating virus-induced modifications of saccharide-binding "receptor functions" in vivo. Findings were that normal hepatic clearance of aggregated albumin and of ovalbumin is slowed from the onset of viremia. Fractional catabolic rates of amannosyl-ovalbumin and amannosyl-IgG are similar in uninfected animals to those seen with native ovalbumin or with mannose-terminated IgG in LDV-infected animals. Ovalbumin and aggregated albumin were also found to be mutually competitive for hepatic uptake in uninfected animals. It is proposed that LDV, which replicates in cells of the mononuclear phagocyte system (reticuloendothelial system), alters the clearance functional state of fixed tissue macrophage, thereby explaining in part the protracted circulatory longevity of several enzymes, aggregated albumin and mannose-terminated ovalbumin, and IgG in LDV-infected mice.