The biological activities of dengue 2 virus on its target cells, namelymacrophages and neutrophils were investigated. Preliminary results showed thatpolyethylene glycol precipitated dengue 2 virus acted as a chemoattractant for peritonealcells of Balbc/I mice and for established rnonoctyesfmacrophage cell lines (WEHI265.1). This in nine response was also seen in vitro using Boyden Chemotaxis chambersand was found to be inhibited by specific viral antibodies. The ability of thevirus to activate these cells was then evaluated. Treatment of the peritoneal cells withvirus induced a respiratory burst with the production of picomoles of superoxides. Inaddition, the virus induced production of reactive nitrogen intermediates (1-2 uM) andalso resulted in exocytosis of Iysozyme. Adhesiveness was also observed and appearedto increase with higher concentrations of the virus. The above results demonstratethat increased adhesiveness and activation are induced following treatment of peritonealcells and the cell line WEHI 265.1 with dengue virus.