Replication of hemorrhagic fever viruses in monocytic cells

Monocytes play a central role in protection against many viruses. In some infections they are target cells for viral replication. There is increasing evidence that these cells may also be important in regulation of hemostasis. The part played by monocytic cells in the pathogenesis of hemorrhage in the viral hemorrhagic fevers is presently uncertain. Monocytes and monocytic cell lines have been used to investigate the ability of viruses to infect these cells in vitro. Several factors may affect the ability of a particular virus to infect monocytic cells, including specific antiserum to virus and the degree of cellular maturation. The effect of cellular maturation on the replication of Rift Valley fever virus in the U937 cell line is discussed in light of studies on the infectivity of other viruses for monocytic cells. Data supporting the ability of specific antibody to enhance the infectivity of Pichinde virus and Lassa fever virus for U937 cells are presented.