Biology subjects

Kvac, M.

Publications and source records attributed to Kvac, M..

4 recordsLinked to original sources

bioRxiv2023

The effect of host admixture on wild house mouse gut microbiota is weak when accounting for spatial autocorrelation.

The question of how interactions between the gut microbiome and vertebrate hosts contribute to host adaptation and speciation is one of the major problems in current evolutionary research. Using bacteriome and mycobiome metabarcoding, we examined how these two components of the gut microbiota vary with the degree of host admixture in secondary contact between two house mouse subspecies (Mus musculus musculus and M. m. domesticus). We used a large dataset collected at two replicates of the hybrid zone and model-based statistical analyses to ensure the robustness of our results. Assuming that the microbiota of wild hosts suffers from spatial autocorrelation, we directly compared the results of statistical models that were spatially naive with those that accounted for spatial autocorrelation. We showed that neglecting spatial autocorrelation can drastically affect the results and lead to misleading conclusions. The spatial analyses showed little difference between subspecies, both in microbiome composition and in individual bacterial lineages. Similarly, the degree of admixture had minimal effects on the gut bacteriome and mycobiome and was caused by changes in a few microbial lineages that correspond to the common symbionts of free-living house mice. In contrast to previous studies, these data do not support the hypothesis that the microbiota plays an important role in host reproductive isolation in this particular model system.

evolutionary biology↗

bioRxiv2023

Dietary environmental factors shape the defence against infection with Cryptosporidium

Cryptosporidium is a leading cause of diarrheal-related deaths in children, especially in resource-poor settings. It also targets the immunocompromised, chronically infecting people living with HIV and primary immunodeficiencies. There is no vaccine or effective treatment. While it is known from human cases and animal models that CD4+ T-cells play a role in curbing Cryptosporidium, the role of CD8+ cells remains to be defined. Using a Cryptosporidium tyzzeri mouse model, we show that gut-resident CD8+ intraepithelial lymphocytes (IELs) confer resistance to parasite growth. CD8+ IELs express, and are dependent on, the ligand-dependent transcription factor aryl hydrocarbon receptor (AHR). AHR deficiency reduced CD8+ IELs, decreased their cytotoxicity, and worsened infection. Transfer of CD8+ IELs rescued severely immunodeficient mice from death following Cryptosporidium challenge. Finally, dietary supplementation of the AHR pro-ligand indole-3-carbinol to new-born mice promoted resistance to infection. Therefore, common dietary metabolites augment the host immune response to cryptosporidiosis, protecting against disease.

immunology↗

bioRxiv2021

Cross-border investigations on the prevalence and transmission dynamics of Cryptosporidium species in dairy cattle farms in western mainland Europe

Cryptosporidium is comprised an apicomplexan parasitic protist, which infects a wide range of hosts, causing cryptosporidiosis. In cattle farms, the incidence of cryptosporidiosis results in high mortality in calves leading to considerable economic loss in the livestock industry. Infected animals may also act as a major reservoir of Cryptosporidium spp., in particular C. parvum, the most common cause of cryptosporidiosis in calves. This poses a significant risk to other farms via breeding centres, to trading of livestock and to human health. This study, funded by the Interreg-2-seas programme, is a part of a global project aimed at strategies to tackle cryptosporidiosis. To reach this target, it was essential to determine whether prevalence was dependent on the studied countries or if the issue was borderless. Indeed, C. parvum occurrence was assessed across dairy farms in certain regions of Belgium, France and the Netherlands. At the same time, the animal-to-animal transmission of the circulating C. parvum subtypes was studied. To accomplish this, 1084 faecal samples, corresponding to 57 dairy-farms from all three countries, were analysed. Well-established protocols amplifying the 18S rDNA and gp60 genes fragments, followed by DNA sequencing, were used for the detection and subtyping C. parvum; the DNA sequences obtained were further characterised using a combination of bioinformatics and phylogenetics methods. Our results show 25.7%, 24.9% and 20.8% prevalence of Cryptosporidium spp. in Belgium, France and the Netherlands respectively. Overall, 93% of the farms were Cryptosporidium positive. The gp60 subtyping demonstrated a significant number of the C. parvum positives belonged to the IIa allelic family, which has been also detected in humans. Consequently, this study highlights how widespread is C. parvum in dairy farms and endorses cattle as a major carrier of zoonotic C. parvum subtypes, which subsequently pose a significant threat to human health.

microbiology↗

bioRxiv2017

Metabolic changes of the host-pathogen environment in a Cryptosporidium infection

Cryptosporidium is an important gut microbe whose contributions towards infant and immunocompromise patient mortality rates are steadily increasing. Current techniques for diagnosing, curing or simply understanding the biology of the parasite are few and far between, relying on a combination of in-silico predictions modelled on a varied and unique group of organisms and medical reports. The development of an in-vitro culture system, using COLO-680N cells, has provided the Cryptosporidium community with the opportunity to expand its toolkit for investigating this disease. One area in particular that is sorely overlooked is the metabolic alterations upon infection. Existing research is extremely limited and has already shown that significant variation can be found between the metabolome of different infected host species. Using a 1H Nuclear Magnetic Resonance approach to metabolomics, we have explored the nature of the mouse gut metabolome as well as providing the first insight into the metabolome of an infected cell line. Through a combination of Partial Least Squares Discriminant Analysis and predictive modelling, we exhibit new and potentially game changing insights into the effects of a Cryptosporidium parvum infection, while verifying the presence of known metabolic changes. Of particular note is the potential contribution of host derived taurine to the diuretic aspects of the disease previously attributed to a solely parasite based alteration of the gut environment. This practical and informative approach can spearhead our understanding of the Cryptosporidium-host metabolic exchange and thus provide novel targets for tackling this deadly parasite.

microbiology↗