Theileria annulata: Alterations in phosphoprotein and protein kinase activity profiles of infected leukocytes of the bovine host, Bos taurus

Abstract

The phosphoprotein profiles of T. annulata-infected and uninfected leukocyte cell lines were compared by both in vivo and in vitro labeling assays. Three phosphoproteins were unique to T. annulata-infected cells, while a further two were quantitatively increased relative to uninfected cells. In addition, two proteins were present and phosphorylated only in the uninfected cell lines, suggesting either a repression of these proteins or their dephosphorylation upon infection of the host cell by the parasite. In order to determine if alterations in protein kinase activity may be responsible for these differences, as opposed to levels of available substrate, an in situ electrophoretic protein kinase assay was developed. This assay allowed a crude separation of protein kinases and revealed alterations in the protein kinase profile of Theileria-infected cells which reflected the differences observed in phosphoprotein profiles. Two protein kinases were unique to infected cells, a further two were more active in infected cells while one was more active in uninfected cells.