CHARACTERIZATION OF THEILERIA-PARVA WHICH INFECTS WATERBUCK (KOBUS-DEFASSA)

Theileria-free waterbuck (Kobus defassa) born in captivity were succes sfully infected with Theileria parva sporozoites derived from ticks in fected by feeding on African buffalo (Syncerus caffer). All waterbuck underwent mild infections with the development of sporadic schizont an d piroplasm parasitosis when inoculated with sporozoite doses lethal t o cattle. A carrier state of T. parva was demonstrated by feeding clea n R. appendiculatus nymphs on two of these infected waterbuck. Tick ba tches from these waterbuck on 2 of 5 occasions transmitted lethal Thei leria infections to cattle. In a separate experiment, waterbuck cells were infected and transformed in vitro by T. parva sporozoites derived from buffalo but not by cattle-derived T. parva (Muguga) sporozoites. Waterbuck cells infected in vitro with T. parva isolated from buffalo were inoculated into autologous waterbuck but no infections developed . Theileria parva isolates generated in this study from various source s were characterized using anti-T. parva schizont monoclonal antibodie s (MAbs), and it was found that buffalo-derived and waterbuck-passaged isolates had different profiles. Species-specific synthetic oligonucl eotide probes, restriction fragment length polymorphism (RFLP) analysi s with cloned T. parva DNA probes, and DNA sequence analysis of the p6 7 sporozoite antigen gene confirmed that the waterbuck-passaged parasi te was T. parva. The Tpr repetitive probe hybridization patterns from the waterbuck-passaged parasites were different from the other samples tested. The ribosomal genotype of the waterbuck-passaged T. parva was similar to that of cattle-derived T. parva Muguga. Analyses with both probes and MAbs suggested that a minor parasite population present wi thin the T. parva 7014 buffalo-derived stock had been selected during waterbuck passage. A variable region of the p67 sporozoite antigen gen e of the waterbuck-passaged T. parva was similar to that of cattle-der ived T. parva stocks and different from that of buffalo-derived parasi tes. Based on these results, methods were suggested to confirm and qua ntitate the involvement of waterbuck in the epidemiology of cattle the ileriosis.