A proposed mechanism for the inhibition of vaccinia virus by mouse macrophages.

Abstract

An investigation of the mechanism of resistance expressed by normal mouse macrophages against lHD vaccinia virus infection was conducted~ Results from virus growth assays seemed to show that vaccinia virus is incapable of multiplying in unstimulated mouse macrophages and instead is degraded by them. Autoradiography experiments determined that no significant viral DNA synthesis occurred. This indicated that the mouse macrophage inhibited viral infection at an early stage of virus-macrophage interaction. Results from virus growth assays involving peritoneal macrophages from immature mice indicated that this natural resistance is expressed prior to the fourth week of life. Incubation of vaccinia virus in susceptible rabbit macrophage or resistant mouse macrophage lysates resulted in a slight drop in virus titer. Because no dramatic viral destruction was observed, it appeared that only the intact cell is responsible in some way for the expression of resistance or susceptibility to vaccinia infection. The role of lysosomal activation in mouse macrophage resistance to vaccinia was investigated. Acid phosphatase staining techniques revealed the activation of lysosomes in vaccinia infected mouse but not rabbit macrophages. It is suggested that the ability of mouse macrophage lysosomes to activate may play a role in the natural resistance to vaccinia.