Neutralization of different strains of murine cytomegalovirus (MCMV)-effect ofin vitro passage

Abstract

Two strains of mouse cytomegalovirus (MCMV) propagated in mouse salivary glands could be distinguished in neutralization tests. Cell (mouse embryo fibroblast)-passaged virus of either strain was generally 10–20 times easier to neutralize than virus produced in mouse salivary glands. Evidence was obtained that mouse immunoglobulin was attached to virus particles in salivary gland preparations. First, antibody to mouse immunoglobulin inactivated salivary gland virus but not cell culture-grown virus. Second, virus obtained from mice early after infection, before antibody production, was as easy to neutralize as cell culture-grown virus. The attached immunoglobulins were CMV-specific, non-neutralizing, and interfered with the action of neutralizing antibody. Non-neutralizing antibodies that bind to infectious virus particles are present in mouse serum at the time salyvary glands are harvested, 3 weeks after infection.