Possible mechanisms for the transport of Semliki forest virus into and within mouse brain

Abstract Virus transport from the lumen of the blood vessels to the parenchymal cells of mouse brain infected with Semliki forest virus is studied by electron microscopy. Two main possible mechanisms of virus transport are suggested. Coated vesicles forming at the endothelial surface of the vascular lumen would appear to absorb virus particles from the blood and then transport the virus to the basement membrane and release them. Then through pressure gradients virus appears to be dispersed into extracellular spaces around brain cells. These cells adjacent to the virus form further coated vesicles by which the virus is absorbed into the cell. Actively migrating cells containing virus e.g. mononuclear cells, polymorphonuclear leucocytes and microglial cells may also play some role in the transport of virus.