Stage-specific expression of protease genes in the apicomplexan parasite, Eimeria tenella

Abstract

BackgroundProteases regulate pathogenesis in apicomplexan parasites but investigations of proteases have been largely confined to the asexual stages of Plasmodium falciparum and Toxoplasma gondii. Thus, little is known about proteases in other Apicomplexa, particularly in the sexual stages. We screened the Eimeria tenella genome database for proteases, classified these into families and determined their stage specific expression.ResultsOver forty protease genes were identified in the E. tenella genome. These were distributed across aspartic (three genes), cysteine (sixteen), metallo (fourteen) and serine (twelve) proteases. Expression of at least fifteen protease genes was upregulated in merozoites including homologs of genes known to be important in host cell invasion, remodelling and egress in P. falciparum and/or T. gondii. Thirteen protease genes were specifically expressed or upregulated in gametocytes; five of these were in two families of serine proteases (S1 and S8) that are over-represented in the coccidian parasites, E. tenella and T. gondii, distinctive within the Apicomplexa because of their hard-walled oocysts. Serine protease inhibitors prevented processing of EtGAM56, a protein from E. tenella gametocytes that gives rise to tyrosine-rich peptides that are incorporated into the oocyst wall.ConclusionEimeria tenella possesses a large number of protease genes. Expression of many of these genes is upregulated in asexual stages. However, expression of almost one-third of protease genes is upregulated in, or confined to gametocytes; some of these appear to be unique to the Coccidia and may play key roles in the formation of the oocyst wall, a defining feature of this group of parasites.

Molecular Characterization and Functional Analysis of a Novel Calcium-Dependent Protein Kinase 4 from Eimeria tenella

“…However, during this period, sporozoites are present in sporulated oocysts, and the energy required by sporozoites is provided by oocysts, so metabolism is moderate [47, 48]. To adapt to this mechanism, physiological activity of sporozoites is regulated at the gene level [49]. Protein translation consumes more energy in sporozoites, therefore mRNA for EtCDPK4 was significantly higher in the sporozoites stage.…”

Genome-wide analysis of differentially expressed profiles of mRNAs, lncRNAs and circRNAs in chickens during Eimeria necatrix infection

“…In recent years, finding key molecules in the host-parasite interaction is becoming an alternative approach for analyzing pathogenic mechanisms and exploring novel targets for developing drugs and vaccine candidates to control parasitic diseases [16][17][18][19][20]. Using the complementary DNA (cDNA) microarray technique, a great number of differentially regulated mRNA molecules in chicken intestines have been identified after infections with E. tenella [4,21], E. acervulina [21][22][23][24] and E. maxima [9,21,22].…”

Eimeria genomics: Where are we now and where are we going?

“…The requirement for microgram quantities of total RNA for library preparation restricted transcriptomic sequencing to only the most accessible lifecycle stages, hindering understanding of much of the eimerian life cycle's complexity. These problems have been overcome for some species and life cycle stages, such as E. tenella gametocytes, where specific culture and recovery protocols have allowed complementation of previous genomic analyses through development of the first RNAseq data (Katrib et al, 2012;Walker et al, 2015). Life cycle stages including trophozoites and developing schizonts are yet to be sampled, but complementary techniques including laser dissection from in vitro or in vivo cultured samples, ex vivo explant culture and fluorescence-activated cell sorting (FACS) of parasites transfected to express fluorescent reporter genes (Clark et al, 2008;Yan et al, 2009) offer good opportunities to access these stages.…”