Detection of a carrier state in Theileria parva-infected cattle by the polymerase chain reaction

Abstract

Two sets of oligonucleotide primers, one derived from a repetitive sequence and the other from the gene encoding a 67 kDa sporozoite antigen of Theileria parva, were used to amplify parasite DNA from the blood of T. parva-infected carrier cattle using the polymerase chain reaction (PCR). PCR amplification products were obtained from 15 carrier cattle infected with one of 4 different T. parva stocks. Successful amplifications were performed using DNA from 2 cattle infected with T. p. parva Pemba Mnarani, 10 cattle infected with T. p. parva Marikebuni, 2 cattle infected with T. p. bovis Boleni and 1 animal infected with T. p. lawrencei 7014. No amplification products were obtained from any of 7 cattle which had been infected with the T. p. parva Muguga stock. A synthetic oligonucleotide, which hybridized specifically to T. p. parva Marikebuni DNA among 6 T. parva stocks tested, was designed using sequence data from within the region of the T. parva genome amplified by the repetitive sequence primers. The oligonucleotide was used to probe PCR products and to increase the sensitivity and specificity of carrier animal detection. Southern blot analysis using a T. parva repetitive sequence probe demonstrated the existence of restriction fragment length polymorphisms between parasites isolated from T. p. parva Marikebuni-infected carrier cattle. The use of the PCR and other methods of carrier animal detection are discussed.

Dogmas and misunderstandings in East Coast fever

“…Other stocks which might have been thought to be complex in nature, such as T. parva Pugu, which was isolated from ticks collected at a cattle holding ground near Dar es Salaam, also do not induce a carrier state (Dolan 1986a). However, it is now firmly established in both field and laboratory that the carrier state is a widespread phenomenon among stocks derived from buffalo and cattle (Brocklesby & Barnett 1966;Young 1981;Dolan 1986a;Bishop et al 1992). To paraphrase an argument from Dolan (1986a) and Young et al (1986), 'as infected ticks cleanse themselves of infection whilst feeding and transovarial transmission does not occur, parasite survival would be precarious if persistence in the vertebrate host was not common'.…”

Survey on infection rate, vectors and molecular identification of Theileria annulata in cattle from North West, Iran

“…However, the method requires expertise because these parasites have similar morphological features and therefore may confuse the examiner when mixed infections occur. Serological tests are also used; however there are some limitations with the specificity and sensitivity these tests (Bishop et al 1992;Dolan 1986). An exact differentiation between these parasites is crucial to understanding their epidemiology.…”

“…An exact differentiation between these parasites is crucial to understanding their epidemiology. The detection of Theileria infection in carrier animals by DNA amplification has been a powerful tool for epidemiological investigation, since these animals represent an important source of alimentary infection of Ixodidae ticks (Bishop et al 1992). In this study two main diagnostic methods including Giemsa staining, as the common procedure in Iran and semi-nested PCR, as a highly sensitive and specific method were used to detect the rate of cattle infected with T. annulata in Ardabil and East Azarbayjan provinces in North West part of Iran.…”

Molecular and phylogenetic analysis of the partial tams1 gene sequence of a vaccine strain of Theileria annulata

“…d'Oliveira reported the use of PCR for sensitive and specific amplification of T. annulata DNA from blood samples obtained from carrier cattle in 1995 (Shiels et al, 1994;d'Oliveira et al, 1995). The advent of PCR technology followed by sequencing has greatly allowed the development of sensitive diagnostic assays and phylogenetic studies for T. annulata (Bishop 1992). The present work was undertaken with an objective of studying the genetic relationship of Iranian vaccine strain (Vaccine-ir68) with other isolates from different parts of the world, based upon the incomplete sequence of Tams1 gene.…”