Workgroup of Comparative Immunology: RNDr. Pavel Hyršl Ph.D.

Keywords

innate immunity, insect immunity, entomopathogenic nematodes, eicosanoids, silkworm, Bombyx mori, wax moth, Galleria mellonella, Drosophila melanogaster, Photorhabdus bacteria, fish immunology, immunology of birds, comparative immunology

Head of laboratory: RNDr. Pavel Hyršl, Ph.D.
Office: A36/123
E-mail: hyrsl@mail.muni.cz
Phone: 549 494 510
Teaching
Publications
Projects
Private web page

 

Postdocs:

DSC_7258a

Ph.D. students:

Bachelor and master students:

 

Innate and adaptive immunity

Immune reactions of vertebrates comprise activities that change during an individual’s life (adaptive immunity) and reactions that are inherited (innate immunity). The adaptive and innate branches of the immune system interact during most vertebrate immune reactions. This integrated response makes it often difficult to attribute an observed effect to one of the two branches of immune system, although this information is important for the design of therapeutic strategies. For instance only adaptive but not innate responses can be modified through vaccination and innate responses can only be specifically targeted if the involved signal induction pathways are known.

Insect Immunity

Just like vertebrates insects rely on both humoral and cellular activities to fight against infections, although most immune responses involve both of these branches of immune system. Two major immune organs of insect are fat body, which is functionally akin to the vertebrates’ liver and blood cells which are collectively called haemocytes. In addition many other organs contribute to immune reactions; in particular organs at the interface with the outside world such as gut. Humoral factors are secreted by the fat body and by haemocytes into the haemolymph. They include for example highly potent antimicrobial peptides and the enzyme phenoloxidase which mediates production of quinones that are both cytotoxic and involved in crosslinking of proteins (coagulation reactions). Cellular activities in insect immune system rely on different classes of haemocytes.

Goals

Insects have radiated into more species, colonized a greater range of habitats and defined more biological niches than any other group of animals. This is of immunological interest because the success of insects is linked to their ability to defend themselves against an amazing range of pathogenic and parasitic organisms. In our laboratory we focus upon the study of defensive response of insect, because this is a rapidly expanding field of research and provides unique insights into the innate immune mechanism. The insect immune system is different from mammalian system and acts with a combination of humoral and cellular responses to invading microorganisms which in certain instances can be compared to the innate immune system of vertebrates.

The long-term goal of this laboratory is the study of immune mechanisms or more appropriately the patho-physiology and also the immuno-physiology of insects. Defensive responses can be triggered in insects subjected to stress conditions and also because of microbial invaders. All these factors such as the influence of temperatures, injury, injection of pathogens, effect of chemicals such as pollutants or insecticides, natural invasion of entomopathogenic nematodes, application of hormones etc. are reflected in changes in protein spectrum of hemolymph as well as other associated changes in the insect physiology.

Copulation of Bombyx mori

To investigate these changes as a result of the immune response, we use model insects such as the silkworm (Bombyx mori), greater wax moth (Galleria mellonella) and fruit fly (Drosophila melanogaster). Big advantage of the use of G. mellonella is that large culture and a constant supply of this model organism can be obtained by its continuous breed in laboratory under standard conditions, whereas silkworms are reared only seasonally. Except of these two insect species we use mutants and RNAi lines of genetically tractable insect – D. melanogaster.

Majority of the experimental approaches focus on the hemolymph of these model organisms. Used techniques include SDS-PAGE (gradient polyacrylamide gel electrophoresis in sodium dodecyl sulfate that enables to detect proteins in the hemolymph at interval 6,5 – 200 kDa) followed by densitometric analysis with software, luminometry, various biochemical sets and standard immunological methods such as ELISA, radial diffusion in agarose etc.

Entomopathogenic nematodes
Heterorhabditis bacteriophora

Presently we focus on entomopathogenic nematodes which are known to be very important for biological control of several insect pests. In our experiments Heterorhabditis bacteriophora, Steinernema feltiae and Steinernema glaseri are used. These species differs in pathogenity and their recognition as non-self matter in insect hosts. Encapsulation mediated by haemocytes can be studied microscopically as the basic immune defense reaction of host insects against nematodes.

Entomopathogenic nematodes of the genus Heterorhabditis contains symbiotic bacteria Photorhabdus, the only one known terrestrial specie with natural bioluminescence. The research in this field includes luminometric measurement of bioluminescence and its relationship to bacterial optical density, temperature etc. Practical use is possible in bacteriolytic test systems.

We are using natural invasion of entomopathogenic nematodes to Drosophila larvae for bacterial infection studies. It is possible to increase susceptibility of fruit flies to the infection by nematodes via blocking of the candidate genes. By this method we study especially relationship of haemolymph coagulation to the immune responses and also the signalling role of eicosanoids.

We are also analyzing phagocytic properties of the leukocytes (oxidative burst) and antibacterial effects of blood plasma (complement system, lysozyme) in fish and birds innate immunity studies. Several species of fresh water fish (carp, tench, crucian carp) and birds (quail, partridge) are used in these experiments.



Current posters

Collaborating institutions

Professional stays in laboratory

Researchers

Students

Current research