TICK SALIVARY-GLAND EXTRACTS PROMOTE VIRUS GROWTH IN-VITRO

Saliva of blood-feeding arthropods promotes infection by the vector-bo rne pathogens they transmit. To investigate this phenomenon in vitro, cultures of mouse L cells were treated with a salivary gland extract ( SGE) prepared from feeding ticks and then infected with vesicular stom atitis virus (VSV). At low input doses of VSV, viral yield was increas ed 100-fold to 10000-fold by 16-23 h post-infection compared with untr eated cultures, and depending on the SGE concentration. SGE-mediated a cceleration of viral yield corresponded with the earlier appearance of VSV nucleocapsid protein as detected by 2-dimensional electrophoresis of infected cells. The observation that physiological doses of virus (i.e. doses likely to be inoculated by an infected arthropod vector in to its vertebrate host during blood-feeding) respond to SGE treatment in vitro provides a new opportunity for identifying the factors in tic k saliva that promote virus transmission in vivo.