Pretoria Virus: A New African Agent in the Tickborne Dera Ghazi Khan (Dgk) Group and Antigenic Relationships within the Dgk Group1

Pretoria (PRE) virus (strain EgArt 3089), a new arboviral agent, was isolated from a pool of 2 female Argas (Argas) africolwnbae Hoogstraal et al., 1975, taken near a nest of a Cape Rock Pigeon, Columba guinea phaeonata Gray, house at Derdepoort, Pretoria District, Republic of South Africa. The complement-fixation test shows EgArt 3089 to be a member of the Dera Ghazi Khan (DGK) group and crossneutralization tests show it to be distinct from each other prototype member of the DGK group. PRE virus is pathogenic for suckling mice and hamsters but not for adult mice, weanling guinea pigs, and rabbits. Results of preliminary studies of antigenic relationships within the DGK group suggest that the 2 Asian and the 3 African Argas-infecting members each form separate subgroup, with the prototype DGK virus (known only from a single strain from an ixodid tick in Pakistan) occupying the anomalous position of sharing common properties with both subgroups.