Analysis of the inhibitory effect of peritoneal macrophages on the spread of herpes simplex virus

Peritoneal macrophages obtained from mice after an intraperitoneal injection of tryptose peptone inhibited the development of herpes simplex virus type 2 plaques in syngeneic mouse embryonic fibroblasts. In contrast, peritoneal macrophages, spleen cells, and thymocytes from untreated mice showed only a minimal inhibitory effect on the development of viral plaques. The effect was age dependent. Macrophages from 2 and 3-week-old mice showed weaker functions, requiring a larger number of cells for an equivalent reduction of plaques and virus yield than those from adult mice. When macrophages were treated with procaine, their phagocytic activity was completely abolished. However the procaine-treated macrophages still could inhibit the development of viral plaques. Peritoneal macrophages did not show any increased cytotoxicity against herpes simplex virus-infected cells; plaque inhibition might rather be attributable to their cytostatic effects on target cells.