Gene Expression Profiling During Early Stages Of Infection Of Bovine Lymphocytes By The Parasite Theileria Parva

ABSTRACT

Theileriosis or East Coast Fever (ECF), a leukemia-like disease of cattle that is endemic in East, Central and Southern Africa, is caused by the protozoan parasite Theileria parva (T. parva), which is transmitted by the brown ear tick vector Rhipicephalus appendiculatus. In an infective tick bite, the sporozoite parasites preferentially infect bovine lymphocytes and develop into intra-cytoplasmic, multinucleated schizonts. Schizont-infected host cells proliferate and exhibit several phenotypes characteristic of cancerous cells. An infected animal dies, within two weeks, from massive pulmonary oedema caused by invasive, blasting and lysed lymphocytes. The objective of this study was to identify the key factors underlying T.parva-infected bovine lymphocytes by generating the profile of gene expression in both the host and the parasite in the early stages of sporozoite infection, that lead to transformation of lymphocytes by schizonts. Random amplified differentially expressed sequences (RADES) -a semi-quantitative reverse transcription-polymerase chain reaction was used to profile the change of gene expression during transformation of bovine lymphocytes subsequent to the in-vitro infection with sporozoites. This study isolated 248 differentially expressed RADES profiles and cloned 37 of them into plasmid vectors for sequencing. 25 plasmids were sequenced out of which 10 were characterized to 8 protein encoding DNA sequences. The eight identified genes were: aldehyde dehydrogenase, transmembrane protein 103, kelch-like 18 proteins, sterol regulatory element-binding protein cleavage-activating protein, F-box only protein 16, zinc-protein 395-like a sequence that flanks the dynein heavy chain gene and that which flanks bovine thymosin beta. The later gene (flanking thymosin beta) was ubiquitous whereas the rest were unique to infected cells alone i.e. existing only due to the interaction of the parasite and host cells. All the eight genes have been shown to be involved in various cell processes–including cell multiplications.