Kariwa H, Arikawa J, Takashima I, Isegawa Y, Yamanishi K, Hashimoto N
Department of Veterinary Public Health, Faculty of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
J Virol Methods. 1994 Sep;49(2):235-44. doi: 10.1016/0166-0934(94)90047-7.
Centrifugation was introduced during virus adsorption to Vero E6 cells to improve the infectivity of hantavirus. Centrifugal adsorption of a stock solution of Hantaan virus strain 76-118 to a monolayer of Vero E6 cells enhanced virus infectivity depending on the centrifugation time and the centrifugal force. The maximum level of infectivity (3.1 x 10(6) FFU/ml) was enhanced after a 2 h centrifugation at 671 x g, which was almost 9-times higher than that of conventional adsorption of the virus at 37 degrees C for 1 h. Vero E6 cells were inoculated with a new hantavirus strain, KI-91-40, isolated with a low infectious titer (400 FFU/ml) from an urban rat and adsorbed by centrifugation. A higher virus titer was detected sooner compared to when using conventional adsorption. To analyze the mechanism of the enhancement, the centrifugation was carried out before and after virus adsorption. The infectivity was reduced when Vero E6 monolayers were centrifuged before virus inoculation. When the centrifugation proceeded after inoculation, the infectivity was almost equal to that without centrifugation. The infectivity was only enhanced when centrifugation was carried out during inoculation. These results indicate that centrifugation promotes a very early event of infection, probably attachment of the virus to cells.
