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The Drosophila Nora virus is an enteric virus, transmitted via feces
Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). (Hultmark)
Zoology Department, Stockholm University, Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia, 3318 Montevideo, Uruguay.
Department of Cell and Molecular Biology, Transmission Electron Microscopy Unit, Faculty of Sciences, Montevideo, Uruguay.
Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). (Hultmark)
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2009 (English)In: Journal of Invertebrate Pathology, ISSN 0022-2011, E-ISSN 1096-0805, Vol. 101, 29-33 p.Article in journal (Refereed) Published
Abstract [en]

 The biology of the Drosophila viruses has not been intensely investigated. Here we have investigated the biology of the Nora virus, a persistent Drosophila virus. We find that injected Nora virus is able to replicate in the files, reaching a high titer that is maintained in the next generation. There is a remarkable variation in the viral loads of individual flies in persistently infected stocks; the titers can differ by three orders of magnitude. The Nora virus is mainly found in the intestine of infected flies, and the histology of these infected intestines show increased vacuolization. The virus is excreted in the feces and is horizontally transmitted. The Nora virus infection has a very mild effect on the longevity of the flies, and no significant effect on the number of eggs laid and the percent of eggs that develop to adults.

Place, publisher, year, edition, pages
2009. Vol. 101, 29-33 p.
Keyword [en]
Drosophila, Nora virus, Horizontal transmission, Enteric virus, Picorna-like virus
National Category
Medical and Health Sciences
URN: urn:nbn:se:umu:diva-22146DOI: 10.1016/j.jip.2009.02.003OAI: diva2:212870
Available from: 2009-04-24 Created: 2009-04-24 Last updated: 2012-05-30Bibliographically approved
In thesis
1. Nora virus as a model to study persistent infection in Drosophila melanogaster
Open this publication in new window or tab >>Nora virus as a model to study persistent infection in Drosophila melanogaster
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Drosophila melanogaster has been widely used as a model organism to study the immune responses against bacteria, fungi, parasites and viruses. Here, I present a D. melanogaster virus as a model to study persistent virus infections. I have discovered and characterized the Nora virus, a small picorna-like RNA virus able to persistently infect D. melanogaster. The Nora virus genome encodes four open reading frames; a feature not present in other picorna-like viruses. The Nora virus is not closely related to any other virus family, but rather is the first virus in a new family of picorna-like viruses. The major replicative proteins of this virus are encoded in the second open reading frame and the capsid proteins are encoded in the fourth open reading frame. The sequence of the capsid proteins are not obviously related to any other previously described protein. By looking at expressed sequence tags (EST) projects, we identified an EST sequence from the parasitic wasp Nasonia which appears to encode proteins that have sequence similarity to the Nora virus capsid proteins. I have shown that the Nora virus persists in the fly intestine however I did not observe serious pathological effects in the infected flies. The virus is shed through feces and the transmission occurs horizontally via the ingestion of virus-contaminated food. Moreover, I observed variability in the viral titers among single flies of the same infected stock. Some flies are able to clear the Nora virus but not others and this phenomenon seems to be titer-dependent. Surprisingly, none of the known Drosophila antiviral responses play a role against the Nora virus. In conclusion, my work shows that studying the Nora virus interaction with the Drosophila immune system can lead to new findings on viral persistence mechanisms of RNA viruses and of Drosophila viral innate immunity.

Place, publisher, year, edition, pages
Umeå: Department of molecular biology, 2009. 39 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1265
Nora virus, Drosophial, persistence, transmission, RNAi, capsid proteins
National Category
Microbiology in the medical area
Research subject
Molecular Biology
urn:nbn:se:umu:diva-22129 (URN)978-91-7264-781-7 (ISBN)
Public defence
2009-05-18, Major Groove, Institution för Molekylärbiologi, byggnad 6L, 09:00 (English)
Available from: 2009-04-28 Created: 2009-04-23 Last updated: 2011-06-22Bibliographically approved

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Habayeb, MazenEkström, Jens-OlaAlbright, ShannonHultmark, Dan
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Department of Molecular Biology (Faculty of Medicine)
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