Herpes simplex virus type I inhibits in vitro differentiation and selectedfunctions of human blood-derived monocytes

We have studied the effect of herpes simplex virus type 1 (HSV1) infection on in vitro differentiation of blood-derived human monocytes into macrophag es using morphological, functional and biochemical parameters that alter du ring macrophage differentiation. Purified preparations of HSV modified the monocyte-macrophage differentiation, in spite of the fact that the virus di d not replicate in monocytes. Disappearance of expression of a monocyte-spe cific surface antigen and the typical development of morphological appearan ce were delayed in HSV- infected cells. Production of the lysosomal enzyme acid phosphatase, which normally increases during differentiation, was also reduced in infected cells. Transcription of the oncogenes c-myc and c-fos, and the Hsp70 gene was modified in cells from some donors but not in other cell preparations. Possible mechanisms of these effects are discussed.