In vitro cultivation studies on the Skalica strain of tick-borne encephalitis virus.

The Skalica strain of tick-borne encephalitis virus was cultivated in mouse organ cultures. In the fluids from spleen, liver, brain and spinal cord cultures, maximum infectivity titres of 8.1--8.3 log LD50/0.01 ml were found 6 and 9 days after inoculation. In the fluids from lymph node and muscle cultures, maximum infectivity titres of 4.2 and 6.5 log LD50/0.01 ml, respectively, were detected 6 days after inoculation. Neither interferon nor haemagglutinin nor complement-fixing antigen was demonstrated in media from explant cultures from the 3rd to the 15th day of cultivation. Fifteen days after seeding, haemagglutination inhibiting antibodies were detected in the fluid phase of lymph node, spleen and liver explant cultures derived from mice infected 6 days previously, as were complement-fixing antibodies in the fluid phase of lymph node, spleen, liver, lung, brain and spinal cord explant cultures derived from mice infected 14 days previously.