Tomley, F. M. | bioRxiv Science

bioRxiv2024

Multi-omics analysis reveals regime shifts in the gastrointestinal ecosystem in chickens following anticoccidial vaccination and Eimeria tenella challenge

Coccidiosis, caused by Eimeria parasites, poses significant economic and welfare challenges in poultry farming. Beyond its direct impact on health, Eimeria infection disrupts enteric microbial populations leading to dysbiosis and increases vulnerability to secondary diseases such as necrotic enteritis, caused by Clostridium perfringens. The impact of Eimeria infection or anticoccidial vaccination on host gastrointestinal phenotypes and enteric microbiota remains understudied. In this study, the metabolomic profiles and microbiota composition of chicken caecal tissue and contents were evaluated concurrently during a controlled experimental vaccination and challenge trial. Cobb500 broilers were vaccinated with a Saccharomyces cerevisiae-vectored anticoccidial vaccine and challenged with 15,000 Eimeria tenella oocysts. Assessment of caecal pathology and quantification of parasite load revealed correlations with alterations to caecal microbiota and host metabolome linked to infection and vaccination status. Infection heightened microbiota richness with increases in potentially pathogenic species, while vaccination elevated beneficial Bifidobacterium. Using a multi-omics factor analysis (MOFA) machine learning model, data on caecal microbiota and host metabolome were integrated and distinct profiles for healthy, infected, and recovering chickens were identified. Healthy and recovering chickens exhibited higher vitamin B metabolism linked to short-chain fatty acid-producing bacteria, whereas essential amino acid and cell membrane lipid metabolisms were prominent in infected and vaccinated chickens. Notably, vaccinated chickens showed distinct metabolites related to the enrichment of sphingolipids, important components of nerve cells and cell membranes. Our integrated multi-omics model revealed latent biomarkers indicative of vaccination and infection status, offering potential tools for diagnosing infection, monitoring vaccination efficacy, and guiding the development of novel treatments or controls.

microbiology↗

bioRxiv2021

Cellular electron tomography of the apical complex in the apicomplexan parasite Eimeria tenella shows a highly organised gateway for regulated secretion.

The apical complex of apicomplexan parasites is essential for host cell invasion and intracellular survival and as the site of regulated exocytosis from specialised secretory organelles called rhoptries and micronemes. Despite its importance, there is little data on the three-dimensional organisation and quantification of these organelles within the apical complex or how they are trafficked to this specialised region of plasma membrane for exocytosis. In coccidian apicomplexans there is an additional tubulin-containing hollow barrel structure, the conoid, which provides a structural gateway for this specialised secretion. Using a combination of cellular electron tomography and serial block face-scanning electron microscopy (SBF-SEM) we have reconstructed the entire apical end of Eimeria tenella sporozoites. We discovered that conoid fibre number varied, but there was a fixed spacing between fibres, leading to conoids of different sizes. Associated apical structures varied in size to accommodate a larger or smaller conoid diameter. However, the number of subpellicular microtubules on the apical polar ring surrounding the conoid did not vary, suggesting a control of apical complex size. We quantified the number and location of rhoptries and micronemes within cells and show a highly organised gateway for trafficking and docking of rhoptries, micronemes and vesicles within the conoid around a set of intra-conoidal microtubules. Finally, we provide ultrastructural evidence for fusion of rhoptries directly through the parasite plasma membrane early in infection and the presence of a pore in the parasitophorous vacuole membrane, providing a structural explanation for how rhoptry proteins (ROPs) may be trafficked between the parasite and the host cytoplasm. SignificanceApicomplexan parasites cause a wide range of human and animal diseases. The apical complex is essential for motility, host cell invasion and intracellular survival within a specialised vacuole called the parasitophorous vacuole. We know that molecules important for all of these processes are secreted from the apical complex via a set of secretory organelles and there is even evidence that some parasite molecules can enter the host cell from the parasitohorous vacuole, but there is little understanding of exactly how this occurs. Here we have used three dimensional electron microscopy to reconstruct the entire apical end of the parasite and whole individual parasites. Our results provide important insights into the structural organisation and mechanisms for delivery of parasite molecules via this important area of the cell.

microbiology↗