Biophysical and biological studies on Jos virus (a new tick-borne virus isolated from Nigeria).

Jos virus possessed no haemagglutinating property within pH range 6.0--6.6 at room temperature and 37 degrees C. Haemagglutination-inhibition tests with Jos virus immune mouse ascitic fluid against other arbovirus antigens further confirmed the lack of serological relationships with any of the major arbovirus groups. Serum neutralisation tests showed that nonspecific neuralising inhibitors of Jos virus were absent in normal sera. Jos virus is highly thermolabile; a sharp reduction of virus infectivity occurred on exposure to various temperatures. Ultraviolet irradiation rapidly inactivated the virus; considerable loss of infectivity occurred within one minute of exposure to ultraviolet light. Electron microscopic studies of infected suckling mouse liver revealed necrosis of hepatocytes, phagocytosis of necrotic debris and mononuclear infiltration. Jos virus produced plaques in Vero and duck embryo cell cultures. Assay of stock virus in these cell cultures and in suckling mice showed that mouse inoculation was more sensitive than plaque assay.