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Anti-parasitic and anti-viral immune responses in insects
Stockholm University, Faculty of Science, Department of Genetics, Microbiology and Toxicology.
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Insects encounter many microorganisms in nature and to survive they have developed counter measures against the invading pathogens. In Drosophila melanogaster research on insect immunity has mainly been focused on infections by bacteria and fungi. We have explored the immune response against natural infections of the parasite Octosporea muscaedomesticae and the Drosophila C virus as compared to natural infections of bacteria and fungi. By using Affymetrix Drosophila GeneChips, we were able to obtain 48 genes uniquely induced after parasitic infection. It was also clearly shown that natural infections led to different results than when injecting the pathogens.

In order to search for the ultimate role of the lepidopteran protein hemolin, we used RNA interference (RNAi). We could show that injection of double stranded RNA (dsRNA) of Hemolin in pupae of Hyalophora cecropia led to embryonic malformation and lethality and that there was a sex specific difference. We continued the RNAi investigation of hemolin in another lepidopteran species, Antheraea pernyi, and discovered that hemolin was induced by dsRNA per se. A similar induction of hemolin was seen after infection with baculovirus and we therefore performed in vivo experiments on baculovirus infected pupae. We could show that a low dose of dsHemolin prolonged the period before the A. pernyi pupae showed any symptoms of infection, while a high dose led to a more rapid onset of symptoms. By performing in silico analysis of the hemolin sequence from A. pernyi in comparison with other Hemolin sequences, it was possible to select a number of sites that either by being strongly conserved or variable could be important targets for future studies of hemolin function.

Place, publisher, year, edition, pages
Stockholm: Institutionen för genetik, mikrobiologi och toxikologi , 2004. , 68 p.
Keyword [en]
Hemolin, Hyalophora cecropia, Antheraea pernyi, Drosophila melanogaster, anti-viral, anti-parasitic, rna interference, microarray, innate immunity
National Category
Genetics
Identifiers
URN: urn:nbn:se:su:diva-224ISBN: 91-7265-930-0 (print)OAI: oai:DiVA.org:su-224DiVA: diva2:191158
Public defence
2004-09-24, sal G, Arrheniuslaboratorierna, Svante Arrhenius väg 14-18, Stockholm, 13:00
Opponent
Supervisors
Available from: 2004-09-02 Created: 2004-09-02Bibliographically approved
List of papers
1. Parasite-specific immune response in adult Drosophila melanogaster: a genomic study
Open this publication in new window or tab >>Parasite-specific immune response in adult Drosophila melanogaster: a genomic study
2004 (English)In: EMBO reports, ISSN 1469-221X, Vol. 5, no 2, 207-212 p.Article in journal (Refereed) Published
Abstract [en]

Insects of the order Diptera are vectors for parasitic diseases such as malaria, sleeping sickness and leishmania. In the search for genes encoding proteins involved in the antiparasitic response, we have used the protozoan parasite Octosporea muscaedomesticae for oral infections of adult Drosophila melanogaster. To identify parasite-specific response molecules, other flies were exposed to virus, bacteria or fungi in parallel. Analysis of gene expression patterns after 24 h of microbial challenge, using Affymetrix oligonucleotide microarrays, revealed a high degree of microbe specificity. Many serine proteases, key intermediates in the induction of insect immune responses, were uniquely expressed following infection of the different organisms. Several lysozyme genes were induced in response to Octosporea infection, while in other treatments they were not induced or downregulated. This suggests that lysozymes are important in antiparasitic defence.

Place, publisher, year, edition, pages
Narure Publishing Group, 2004
Identifiers
urn:nbn:se:su:diva-23281 (URN)10.1038/sj.embor.7400073 (DOI)
Note
Part of urn:nbn:se:su:diva-224Available from: 2004-09-02 Created: 2004-09-02 Last updated: 2010-01-08Bibliographically approved
2. Hemolin gene silencing by ds-RNA injected into Cecropia pupae is lethal to next generation embryos
Open this publication in new window or tab >>Hemolin gene silencing by ds-RNA injected into Cecropia pupae is lethal to next generation embryos
2002 (English)In: Insect Molecular Biology, ISSN 0962-1075, Vol. 11, no 3, 267-271 p.Article in journal (Refereed) Published
Abstract [en]

There is increasing evidence of an intimate connection between participants in the innate immune system and in development. Molecules involved in the determination of dorso-ventral polarity in Drosophila have related counterparts in the signalling pathways for immune gene activation in both insects and mammals. Hemolin from the Giant silkmoth, Hyalophora cecropia, identified as a bacteria-inducible molecule and a member of the immunoglobulin superfamily, is present as protein and transcripts in oocytes and embryos. We used RNA interference (RNAi) to investigate H. cecropia gene function in vivo and demonstrated that Hemolin is crucial for the normal development of embryos. When RNAi-females were mated, no larvae emerged from their eggs and when dissected, the eggs revealed malformed embryos. Western blot analysis confirmed the lack of Hemolin gene products. We conclude that Hemolin is necessary for development, since the silencing of Hemolin gene expression leads to embryonic lethality

Keyword
dsRNA • RNA interference • hemolin • development • insect immunity
National Category
Biological Sciences
Identifiers
urn:nbn:se:su:diva-23282 (URN)10.1046/j.1365-2583.2002.00334.x (DOI)
Note
Part of urn:nbn:se:su:diva-224Available from: 2004-09-02 Created: 2004-09-02 Last updated: 2010-01-08Bibliographically approved
3. Baculovirus and dsRNA induce Hemolin, but no antibacterial activity, in Antheraea pernyi
Open this publication in new window or tab >>Baculovirus and dsRNA induce Hemolin, but no antibacterial activity, in Antheraea pernyi
2004 (English)In: Insect Molecular Biology, ISSN 0962-1075, Vol. 13, no 4, 399-405 p.Article in journal (Refereed) Published
Abstract [en]

Hemolin is one of the haemolymph proteins most strongly induced upon bacterial infection in Lepidoptera. When we applied RNA interference (RNAi) to suppress Hemolin expression in the Chinese oak silk moth Antheraea pernyi, we discovered that Hemolin is induced by double-stranded RNA (dsRNA) per se. As dsRNA is recognized as a virus pattern molecule, we then investigated the effect of a baculovirus (ApNPV) infection. We found that Hemolin is induced and expressed with similar kinetics as upon dsRNA injection. Notably, no Attacin gene expression or antibacterial activity was recorded. When baculovirus and high amounts of dsRNA were coinjected, the viral symptoms appeared earlier with Hemolin dsRNA than with GFP dsRNA. This indicates that silencing of hemolin affected the progress of the viral infection.

Place, publisher, year, edition, pages
Royal Entomological Society, 2004
Keyword
hemolin • baculovirus • dsRNA • innate immunity • antiviral response
National Category
Biological Sciences
Identifiers
urn:nbn:se:su:diva-23283 (URN)10.1111/j.0962-1075.2004.00497.x (DOI)
Note
Part of urn:nbn:se:su:diva-224Available from: 2004-09-02 Created: 2004-09-02 Last updated: 2010-01-08Bibliographically approved
4. Molecular characterization, immunological and phylogenetic analysis of Hemolin, in the Chinese oak silkmoth, Antheraea pernyi
Open this publication in new window or tab >>Molecular characterization, immunological and phylogenetic analysis of Hemolin, in the Chinese oak silkmoth, Antheraea pernyi
Show others...
Manuscript (Other academic)
Identifiers
urn:nbn:se:su:diva-23284 (URN)
Note
Part of urn:nbn:se:su:diva-224Available from: 2004-09-02 Created: 2004-09-02 Last updated: 2010-01-13Bibliographically approved

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