抄録
The present report concerns the multiplication of the Japanese encephalitis virus in primary porcine kidney cell cultures. Suckling and weanling pigs were constantly excellent donors of tissues. Viability of trypsinized cells was dependent on washing procedure; this was especially the case with tissues from marketable animals. Confluent sheets were obtained in 5 to 7 days, and the virus was usually inoculated on the 7th to 8th day of incubation. Unfortunately, medium 199 did not support the growth of viruses so well as did the Lactalbumin hydrolysate-Earle's medium. So far tested LE medium fortified with bovine albumin was the best one, although this could be substituted by human albumin or gelatin. The optimal concentration of sodium bicarbonate fell in between 2.5 and 2.6g per liter of medium. At the early stage of adaptation the viruses were sensitive to the lower temperature, while adapted strains were not affected appreciably by the temperature. In order to have a maximal yield relatively large size of inoculum was required, the optimum being 104 to 105 PFU per milliliter of medium. Growth curves showed peak titers at 48 hour of incubation both in cells and fluid phase. Some promissing results were also obtained by submerged cultures.
