East Coast fever (ECF) and Corridor disease (CD) caused by cattle-and buffalo-derived T. parva respectively are the most economically important tick-borne diseases of cattle in the affected African countries. The p67 gene has been evaluated as a recombinant subunit vaccine against ECF, and for discrimination of T. parva parasites causing ECF and Corridor disease. The p67 allele type 1 was first identified in cattle-derived T. parva parasites from East Africa, where parasites possessing this allele type have been associated with ECF. Subsequent characterization of buffalo-derived T. parva parasites from South Africa where ECF was eradicated, revealed the presence of a similar allele type, raising concerns as to whether or not allele type 1 from parasites from the two regions is identical. A 900 bp central fragment of the gene encoding p67 was PCR amplified from T. parva DNA extracted from blood collected from cattle and buffalo in South Africa, Mozambique, Kenya, Tanzania and Uganda, followed by DNA sequence analysis. Four p67 allele types previously described were identified. A subtype of p67 allele type 1 was identified in parasites from clinical cases of CD and buffalo from southern Africa. Notably, p67 allele type 1 sequences from parasites associated with ECF in East Africa and CD in Kenya were identical. Analysis of two p67 Bcell epitopes (TpM12 and AR22.7) revealed amino acid substitutions in allele type 1 from buffalo-derived T. parva parasites from southern Africa. However, both epitopes were conserved in allele type 1 from cattle-and buffalo-derived T. parva parasites from East Africa. These findings reveal detection of a subtype of p67 allele type 1 associated with T. parva parasites transmissible from buffalo to cattle in southern Africa.

28East Coast fever (ECF) and Corridor disease (CD) caused by cattle-and buffalo-derived 29 T. parva respectively are the most economically important tick-borne diseases of cattle in 30 the affected African countries. The p67 gene has been evaluated as a recombinant subunit 31 vaccine against East Coast fever (ECF), and for discrimination of T. parva parasites 32 causing ECF and Corridor disease (CD). The p67 allele type 1 was first identified in cattle-33 derived T. parva parasites from east Africa, where parasites possessing this allele type have 34 been associated with ECF. Subsequent characterization of buffalo-derived T. parva 35 parasites from South Africa where ECF was eradicated, revealed the presence of a similar 36 allele type, raising concerns as to whether or not allele type 1 from parasites from the two 37 regions is identical. A 900 bp central fragment of the gene encoding p67 was PCR 38 amplified from T. parva DNA extracted from blood collected from cattle and buffalo in 39 South Africa, Mozambique, Kenya, Tanzania and Uganda, followed by DNA sequence 40 analysis. Four p67 allele types previously described were identified. A subtype of p67 allele 41 type 1 was identified in parasites from clinical cases of CD and buffalo from southern 42 Africa. Notably, p67 allele type 1 sequences from parasites associated with ECF in East 43 Africa and CD in Kenya were identical. Analysis of two p67 B-cell epitopes (TpM12 and 44 AR22.7) revealed amino acid substitutions in allele type 1 from buffalo-derived T. parva 45 parasites from southern Africa. However, both epitopes were conserved in allele type 1 46 from cattle-and buffalo-derived T. parva parasites from East Africa. These findings reveal 47 detection of a subtype of p67 allele type 1 associated with T. parva parasites transmissible 48 from buffalo to cattle in southern Africa.49 50 3 51 Introduction 52 Theileriosis is a widespread tick-transmitted protozoal disease of wildlife and domestic 53 animals caused by an apicomplexan parasite of the genus Theileria (reviewed in 1). In 54 eastern, central and southern Africa, cattle theileriosis is commonly caused by Theileria 55 parva which occurs naturally in the African buffalo (Syncerus caffer) that is an asymptomatic 56 carrier (2). Theileria parva causes fatal classical East Coast fever (ECF) (3, 4), Corridor 57 disease (5, 6) and January disease (7) occurring in different African countries. This parasite 58 is mainly transmitted by a three-host brown ear tick Rhipicephalus appendiculatus, although 59Rhipicephalus zambeziensis and Rhipicephalus duttoni are also possible vectors (3, 8, 9). 60East Coast fever is estimated to result in an economic loss of about USD 300 due to death 61 of approximately one million cattle annually in the affected countries (reviewed in 1). A 62 live trivalent sporozoite vaccine for control of ECF was developed (10) and has been 63 successfully adopted for use in East Africa (11, 12). Although this vaccine does not confer 64 protection against buffalo-derived T. parva in Kenya (13...