Host and Parasites – University of Copenhagen

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Plant and Environmental Sciences > Research > Organismal Biology > Host and Parasites

Host and Parasites

The Host and Parasites group conducts basic and applied research in the areas of host-parasite interactions. Emphasis is on: 1) Novel techniques to detect and phenotypically analyze infectivity of parasites, 2) Epidemiology of zoonotic parasites, and 3) The use of parasites as model organisms, in particular in relation to toxicity and drug potency.   

Topics:

Assessment of biological infectivity of parasites

Multispectral analysis of parasite eggs

Eggs of parasitic worms possess attributes, which make them potentially suitable for treatment of immune-mediated diseases such as inflammatory bowel disease and multiple sclerosis. Only eggs with a fully developed larva inside have the potential of inducing a positive immune response in patients. Quality assessment of parasite eggs is therefore vital to improve the efficiency of the treatment.

Figure 1: Using image analysis to assess infectivity of Trichuris eggs. (Photo: JM Bruun)

We are developing an application of digital image analysis for assessing qualitative attributes of eggs of the whipworm, Trichuris suis, for instance determining the developmental stage of the eggs, as depicted in Figure 1. The project is coordinated by Christian Kapel.


In vitro
biology of parasites

Pharmaceutical potency of nematode eggs can be evaluated by assessment of their biological infectivity. This can be achieved by development of a controlled in vitro system to examine spontaneous release of larva and larval migratory behavior. The development of such in vitro model depends on understanding basic parameters of the parasite’s lifecycle. 

Figure 2. In vitro hatching of Trichuris suis eggs (Photo: N. Vejzagić)

This project aims to explore mechanisms involved in the development and hatching of Trichuris suis eggs (Fig. 2), and its initial establishment in the definitive host. We hypothesize that stimulation of the pig whipworm eggs in conditions mimicking physiology of the gut environment will result in egg hatching (photo) and subsequent attachment of larva to the intestinal tissue.

Christian Kapel is coordinate this project. Both projects on biological infectivity of parasites are performed in collaboration with Parasite Technologies A/S.

Molecular typing of parasites from the past 

This project seeks to analyze ancient DNA remains from parasite eggs found in archeological samples from Denmark. Initial focus is on the common food-borne infections, Trichuris (whipworm) and Ascaris (round worm). These parasites produce very hard-shelled eggs, which allow them to survive in the environment for extended periods of time, 30.000 years have been reported.

We will test the hypothesis that the exposure to and diversity of food-borne infections (parasites) has changed with cultural and dietary habits, hunting practice and intensity of animal husbandry.

One-thousand years old, intact eggs from Trichuris (left) and Ascaris (right), isolated from soil samples taken from Viborg Søndersø, Denmark (Photo: MJ Søe)

The project is a multidisciplinary effort coordinated by Martin Jensen Søe, Christian Kapel and Brian Lund Fredensborg from the Animal Resource Biology group in collaboration with the Department of Veterinary Disease, experts in ancient DNA analysis at the Natural History Museum, and experts in archeology at the SAXO Institute, University of Copenhagen.

Host suitability of zoonotic tapeworm

The emerging cestode parasite Echinococcus multilocularis can cause the severe chronic disease alveolar echinococcosis (AE) in humans in which growth of the metacestode resembles that of a slow growing malignant tumour in the liver. Canids (typically foxes) act as definitive hosts in which the adult parasite resides in the small intestine releasing eggs that are then consumed by rodent intermediate hosts. The life-cycle is completed upon canid predation of these rodents.

We experimentally investigate the suitability of various species of rodents as intermediate host to E. multilocularis by measuring morphological and immunological parameters following infection. 

Our research forms part of a wider European collaboration (EMIRO – Echinococcus multilocularis in rodents) with the aim to understand the role of different rodent communities in relation to the transmission of E. multilocularis. This collaboration will provide fundamental knowledge to forecast the spread of the parasite into various countries and identify important limitations to the parasite’s transmission. Ian Woolsey, Per Moestrup Jensen, and Christian Kapel coordinate this project in collaboration with researchers from the Finnish Forest Research Institute, Lithuanian University of Health Science, Swedish University of Agricultural Sciences and the University of Zurich

Invertebrate-parasite models for assessment of:

Ecotoxicology

Pathogens and associated diseases are important regulators of host populations. In nature, pathogens often interact with pesticides, which may exacerbate disease pathology. The principal mechanisms behind these interactions remain unknown despite huge potential ramifications to ecosystem services, pest control and drug development.

We experimentally investigate the outcome of and mechanisms behind host/pathogen/ chemical interactions in a flour beetle model exposed to the rat tapeworm (Hymenolepis diminuta) and a pathogenic fungus (Beauveria bassiana) and three common groups of pesticides.

Drug potency

Vertebrate testing of a pharmaceutical is an important requirement before it can be licenced for sale. However using invertebrate models for the initial screening of potential drugs presents several ethical and economic advantages.

We assess the anthelminthic effects of well known drugs (e.g. praziquantel ) and less well known alternatives (e.g. bioactive plant products) on a flour beetle  – rat tapeworm model. Our model allows us to study the effect of drugs on larval tapeworms removed from the host (in vitro) as well as the effect on parasites inside their beetle host.

Direct interactions (red) and indirect interactions (blue) between a host organism, pathogens, and chemical stress.

These projects are coordinated by Brian Lund Fredensborg and Nicolai Vitt Meyling in collaboration with colleagues from Environmental Toxicology, and the Veterinary Parasitology Group at the Department of Veterinary Disease Biology at the University of Copenhagen, and Evolutionary and Ecological Entomology at the University of Sheffield, UK.

Host behavior modification by parasites

The ability of parasites to manipulate the behavior of hosts has fascinated the scientific community for several decades. Manipulating parasites use mind control to steer infected hosts to become much more vulnerable to predation by a suitable next host. Although many cases of host behaviour manipulation are known, surprisingly little is known about the mechanisms behind this fascinating phenomenon.   

We study the proximate causes of behavioural modification using the lancet fluke Dicrocoelium dendriticum and its ant host Formica rufa as model system. The larval stage of the lancet fluke migrates to and lodges itself at the subesophageal ganglion and makes the infected ant climb the vegetation and latch itself on a grass blade (a process called tetania) primarily at times when the herbivorous next host is foraging.  

An interesting feature of this system is that ants also harbour a parasitic fungus with similar behavioural effects, which allows for comparative studies of the mechanisms involved among very different parasite groups.  

The project is coordinated by Brian Lund Fredensborg in collaboration with Nicolai Vitt Meyling and Annette Bruun Jensen from the Insect Pathology and Biological Control group.