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01/01/1970
LIVING WITH GIARDIA: THE BIOLOGY OF CLINICAL OUTCOMES (ID 1710)
Abstract
Abstract Body
Giardia sp. is an intestinal Protozoan parasite of humans and other animal species. The infection is a common cause of diarrhea, and may lead to post-infectious complications, including Irritable Bowel Syndrome. However, giardiasis can also occur in the absence of symptoms. Intriguingly, it appears to protect children against diarrhea in low-income countries with poor sanitation. Hosts may be co-infected with multiple diarrheal-disease causing pathogens, and final disease outcome results from the complex interactions between the host and this polymicrobial cross-talk. Using models of human tissues and live rodent models of co-infection reproducing co-infections with Escherichia-coli and Giardia in humans, our studies shed new light on why the production of symptoms in giardiasis may be so variable. Indeed, direct immunomodulatory effects of Giardia attenuate the pathophysiological responses induced by gastrointestinal pathogens that cause disease via severe inflammation. In addition, our findings demonstrate that high fat versus low fat diets may facilitate pathogenic factors in giardiasis, offering further support to the hypothesis that diet also plays a role in symptom variability. Together, these observations shed new light on the biology of polymicrobial infections in the gastrointestinal tract, and underscore the multifactorial basis of clinical presentation variability in giardiasis. The findings point to new research directions in our attempts at the developing novel strategies to control enteric disease.A LARGE-SCALE COMPARATIVE GENOMICS STUDY OF HUMAN AND RUMINANT STRAINS OF CRYPOSPORIDIUM PARVUM FROM EUROPE (ID 614)
Abstract
Introduction
Cryptosporidium parvum is a major cause of gastrointestinal illness in ruminants and humans, and is highly prevalent in Europe. A few subtypes appear to predominate and cause outbreaks, yet the reasons for this are unclear. We performed the first large-scale comparative genomics study of human- and ruminant-derived C. parvum isolates, aiming at improving our understanding of the population structure and evolution of this pathogen in Europe.
Methods
We sequenced the genome of 116 parasite strains using NGS. Trimmed reads were mapped to a reference genome to obtain a set of filtered Single Nucleotide Polymorphisms (SNPs). We investigated the parasite population structure, and searched for recombination events and for genes under selective pressure.
Results
We identified >32,000 SNPs, mostly located in telomeric and subtelomeric regions. Phylogenetic analysis revealed three strongly supported lineages, with no correlation with host species, country of origin, or subtype. Pairwise SNP distances revealed 12 distinct clusters of highly similar strains, representing outbreaks in humans or localized foci of animal infections. Interestingly, all outbreak clusters belonged to only one of the lineages.
Conclusions
We identified three phylogenetically distinct lineages of C. parvum, one of which comprised all strains linked to outbreaks. Exploring the genomic differences between these lineages may allow identification of genetic determinants with capability to cause outbreaks.
Funding: This work was done as part of the PARADISE project, supported by funding from the European Union’s Horizon 2020 Research and Innovation programme under grant agreement No 773830: One Health European Joint Programme
DEVELOPMENT OF A MULTI-LOCUS SEQUENCE TYPING SCHEME FOR CRYPTOSPORIDIUM PARVUM (ID 907)
Abstract
Introduction
Cryptosporidiosis is an important diarrhoeal disease worldwide. Cryptosporidium parvum infects humans and animals and can cause food- and waterborne outbreaks. However, outbreak investigation and source attribution remain challenging due to the lack of standardised and sufficiently discriminatory typing schemes. We aimed to develop a multi-locus sequence typing (MLST) scheme for C. parvum.
Methods
An in silico pipeline was developed to identify polymorphic sequences suitable for marker development, and markers were selected based on analysis of 137 C. parvum genomes. Markers were tested on a panel of >400 human- and animal-derived C. parvum isolates from 14 countries, representing sporadic, related and outbreak cases. For comparison, we are genotyping selected isolates using a variable-number tandem repeat (VNTR) scheme and the gp60 marker.
Results
Out of 28 primer pairs initially tested in the laboratory, 21 showed strong, consistent and specific amplification. Eight markers, one from each chromosome, were selected for testing on the C. parvum panel using a nested PCR to ensure high sensitivity. Data analysis is ongoing to compare the discriminatory power of this new MLST scheme to the VNTR system and the gp60 marker.
Conclusions
The MLST scheme we have developed is expected to be useful for outbreak investigations, source attribution and One Health surveillance worldwide.
Funding acknowledgement
This study was part of the PARADISE project, supported by funding from the European Union’s Horizon 2020 Research and Innovation programme under grant agreement No. 773830: One Health European Joint Programme.
TROPISM AND PERSISTENCE OF TOXOPLASMA GONDII: FROM PORK CARCASS TO DRY SAUSAGE (ID 549)
Abstract
Introduction
Toxoplasma gondii is an important zoonotic foodborne parasite. Amid the possible transmission routes, meat of infected animals appears to be a major source of infection in Europe. In France, pork is the most consumed meat, and dry sausage is well represented. The risk of transmission via consumption of processed pork products is largely unknown, mainly since processing will affect viability but may not inactivate all T. gondii parasites.
Methods
We investigated the presence of T. gondii in the shoulder, breast, ham and heart tissue of 6 pigs experimentally infected with 1000 oocysts/tissue cysts and 2 naturally infected pigs, by means of MC-qPCR. Muscle tissue of experimentally infected pigs was used to evaluate the impact of manufacturing processes of dry sausages, including different concentrations of nitrites (0–120 ppm) and NaCl (0–26 g/kg), ripening (2 days/16–24°C) and drying (up to 30 days/13°C), by a combination of bioassay, qPCR and MC-qPCR.
Results
DNA of T. gondii was detected in 41.7 % (10/24) of muscle samples and 87.5 % (7/8) of hearts by MC-qPCR. Of dry sausage samples, 94.4 % (51/54) were positive for T. gondii by MC-qPCR or qPCR, however, none except for the untreated dry sausage sample at D0 were positive by mouse bioassay.
Conclusions
The results suggest an uneven distribution of the parasites in the samples examined, and possibly a concentration below the detection limit in some of them as well as an almost immediate effect of additives used in dry sausages on the viability of T. gondii. The results will be used in quantitative microbiological risk assessment for T. gondii.
PARASITIC CNIDARIANS: EVOLUTION OF PARASITISM IN AN ANCESTRAL PHYLUM (ID 1189)
Abstract
Introduction
Cnidaria are an ancestral phylum known for their symbiotic relationships with other organisms. Apart from the strictly parasitic Endocnidozoa (Myxozoans + Polypodium), parasitism has evolved also in other cnidarian groups, but little is known about these other representatives. We aim to summarize the scattered biological information about cnidarian parasites and use molecular methods to uncover their evolution and adaptations.
Methods
Using a concatenated dataset of ribosomal (18S and 28S rDNA) and mitochondrial (COI) genes, we performed an ancestral state reconstruction and phylogenetic analyses to determine the number of entries to parasitism along with entries to epibiosis.
Results
Cnidaria parasitize a large variety of hosts including Ctenophora, Cnidaria, Bryozoa, Mollusca, Annelida and Vertebrata. They have developed an array of morphological and behavioural adaptations, e.g. simplification of body plan and specialised feeding behaviour, that mainly affect the larval stage of their life cycle. We identified at least 8 independent entries to parasitism among Cnidaria, distributed through cnidarian classes with 4 entries in Hydrozoa, 3 in Anthozoa and 1 for Endocnidozoa.
Conclusions
This study provides a unique point of view on parasitic cnidarians biology, emphasizing how molecular data can help uncover the evolution of parasitism in these early metazoans. Future research will include comparative genomics of selected cnidarian parasites to discover adaptions to parasitism in this ancient group.
This project has been funded by Czech Science Foundation (19-28399X).