Attempts to produce Theileria parva-infected mouse cells using cell fusion techniques

Ehrlich ascites tumour (EAT) cells were fused with Theileria parva-infected bovine lymphoid (C2) cells using inactivated Sendai virus. A variety of techniques were employed to try and increase fusion percentage and harvest of heterokaryons. There was no evidence that pre-exposure of C2 cells to Sendai virus or phytohaemagglutinin improved fusion percentage, but the percentage was higher when 10(8) C2 cells were fused with 10(7) EAT cells, as compared with a ratio of 10(7) C2: 10(6) EAT. An increased yield of multinucleate cells was obtained using a calf serum gradient to separate cells of different sizes. An attempt to fuse EAT cells with free macroschizonts was not sucessful. When cells were grown in hypoxanthine/aminopterin/thymidine medium (HAT), T parva appeared to be selectively killed by the aminopterin present; this finding would seem to militate against the use of a HAT selection system to clone parasitised hybrids. C2 cells could be selected out by passage of mixed cultures through mice, but no evidence of parasitosis was detected in EAT cells which became established.