[Effect of the diapause in the Ixodes ricinus (Ixodidae) tick on the multiplication of the tick-borne encephalitis virus in its body].

The tick encephalitis virus was found to multiply more intensively in ticks developing without diapause. Thus, in larvae developing with diapause, in 4 and 8 weeks after they feed on infected animals, the virus titers were 3.0 and 3.5 lg LD50 respectively. At the development without diapause the titers were 4.3 and 5.3, respectively (P less than 0.05). The virus titers in infected nymphs developing without diapause were 2.5 to 3.9 lg LD50 higher than those of the diapausing individuals. In diapausing larvae and nymphs the tick encephalitis virus remained for a long time (8 to 10 weeks) without fall of titers. The fall of virus titers was not recorded either during the moulting of larvae for nymphs and nymphs for imago but in hungry ticks, which were maintained for a long time at 18 to 23 C, the amount of virus gradually diminished.