Comparative transcriptome analysis of Eimeria maxima (Apicomplexa: Eimeriidae) suggests DNA replication activities correlating with its fecundity

Abstract

BackgroundChicken coccidiosis, caused by the infection of Eimeria species, leads to important economic losses to the poultry industry. Vaccination with attenuated live parasites seems to be the best way to control this disease. Attenuated eimerian parasites with shortened prepatent times show great changes in intracellular development compared to their parent strains but the mechanisms involved in these biological differences are still unclear.ResultsIn this study, we obtained a precocious line of E. maxima by sequential selection of 22 generations of early shed oocysts in chickens and performed a comparative transcriptome analysis of three different developmental stages of the precocious line and its parent strain using Illumina high-throughput sequencing. Our E. maxima precocious line showed decreased pathogenicity, reduced fecundity and a greatly shorted prepatent time of only 98 h. We found that typical gene changes in the stage development from unsporulated to sporulated oocyst and from sporulated oocyst to merozoite were marked by upregulated organelle genes and protein translation related genes, respectively. Additionally, major differences between the precocious line and its parent strain were detected in the merozoite stage, characterized by downregulated genes involved in protein cleavage and DNA replication activities.ConclusionsOur study generated and characterized an E. maxima precocious line, illustrating gene expression landscapes during parasite development by transcriptome analysis. We also show that the suppressed DNA replication progress in the merozoite stage in the precocious line may result in its reduced fecundity. These results provide the basis for a better understanding of the mechanism of precocity in Eimeria species, which can be useful in studies in early gametocytogenesis in apicomplexan parasites.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-5090-2) contains supplementary material, which is available to authorized users.

Dual RNA-seq transcriptome analysis of caecal tissue during primary Eimeria tenella infection in chickens

“…In the overall gene expression analysis a general down-regulation of DNA and RNA processing categories and up-regulation of protein expression and energy metabolism categories was observed. A similar pattern was recorded when the first schizogony of E. tenella was monitored in cell culture [ 29 ] and analogous results have been observed for E. maxima when merozoites and oocysts were compared [ 38 ]. Based on these observations one may hypothesise that Eimeria merozoites in general may have a lower level of splicing and increased protein expression compared to sporozoites.…”

Dual RNA-Seq transcriptome analysis of chicken macrophage-like cells (HD11) infected in vitro with Eimeria tenella

“…Of particular note is the ‘Spliceosome’ KEGG pathway, highly downregulated across all time points, and the ‘Ribosome’ and ‘Proteasome’ pathways, highly upregulated across all but the first time point. These same pathways, except for ‘Proteasome’, are also among the most significantly enriched in a comparison of merozoites and sporulated oocysts in E. maxima (Hu et al ., 2018 ), indicating that a lower level of splicing and increased protein expression may be a general feature of Eimeria merozoites compared to sporozoites. The GO categories tell much the same story, with the downregulation of ‘mRNA splicing, via spliceosome’ and upregulation of ‘translation’.…”

A Novel Rhoptry Protein as Candidate Vaccine against Eimeria tenella Infection

“…Sporozoite excystation and purification were consistent with a previous study [ 28 ]. The merozoites were purified from infected chicken ceca, as published previously [ 29 ]. For immunofluorescence, the purified sporozoites and merozoites were adhered to coverslips precoated with poly-lysine and fixed with 4% ( w/v ) paraformaldehyde.…”