Identification of the major genetic determinant for neurovirulence of tick-borne orbiviruses.
Nuttall PA., Moss SR., Jones LD., Carey D.
Three members of the Great Island antigenic subgroup (Kemerovo serogroup) of tick-borne obiviruses produced fatal infections following intracerebral inculation of 2-day-old mice. The average survival times and PFU/LD50 ratios of mice inoculated with Wexford (WEX) virus were significantly greater than those of either Nugget (NUG) or Great Island (GI) virus. Reassortant viruses were isolated following dual infections of cell cultures with a spontaneous temperature-sensitive (ts) mutant of WEX virus, and either NUG wild-type virus or a ts mutant of GI virus. The neurovirulence for mice and derivation of the genomic RNA segments were determined for the reassortants. Analysis of this data revealed that the pathogenic phenotype of the reassortant viruses depended on the parental origin of genomic segment 4. The major genetic determinant of serotype specificity was not shown to influence neurovirulence in these investigations.