Change search
ReferencesLink to record
Permanent link

Direct link
Biology of a small RNA virus that infects Drosophila melanogaster
Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine). (Dan Hultmark)
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Drosophila melanogaster has been extensively used as a model organism to study diverse facets of biology, including host-pathogen interactions and the basic biology of its pathogens. I have used the fruit fly as a model to study elementary aspects of Nora virus biology, such as the role of the different proteins encoded by the virus genome. Nora virus, an enteric virus transmitted via the feca-oral route, does not cause any obvious pathology in the fly, although the infection is persistent. Nora virus genome consists of a positive strand RNA that is translated in four open reading frames (ORF).  Since sequence homology studies did not yield much information about the different Nora virus proteins, I have used the cDNA clone of the virus to construct mutants to identify the specific function of each protein. My results have shown that,

1) The protein(s) encoded by ORF 1 are crucial for the replication of the virus genome.

2) The C-terminus of the ORF 1-encoded protein (VP1), is an inhibitor to the RNAi pathway.

3) The transmembrane domain in the N-terminus of the ORF2-encoded protein (VP2) is important for the formation of Nora virus virions.

4) The ORF 3-encoded protein (VP3) forms α-helical trimers and this protein is essential for the stability of Nora virus capsid.                                                    

I have also performed RNA sequencing to investigate the transcriptional response of D. melanogaster in response to Nora virus infection and my results indicate that,                       

5) The upregulation of genes related to cellular stress and protein synthesis and the downregulation of basal digestive machinery, together with the induction of upd3, implies major gut epithelium damage and subsequent regeneration.

Place, publisher, year, edition, pages
Umeå: Umeå University , 2016. , 52 p.
Keyword [en]
Nora virus, Drosophila melanogaster, virus biology, host-pathogen interaction
National Category
Cell and Molecular Biology
Research subject
Molecular Biology
Identifiers
URN: urn:nbn:se:umu:diva-127352ISBN: 978-91-7601-593-3OAI: oai:DiVA.org:umu-127352DiVA: diva2:1045383
Public defence
2016-12-01, Hörsal 135, Byggnad 9A, Norrlands Universitetssjukhus, Umeå, 14:00 (English)
Opponent
Supervisors
Available from: 2016-11-10 Created: 2016-11-09 Last updated: 2016-11-24Bibliographically approved
List of papers
1. VP3 is crucial for the stability of Nora virus virions
Open this publication in new window or tab >>VP3 is crucial for the stability of Nora virus virions
Show others...
2016 (English)In: Virus Research, ISSN 0168-1702, E-ISSN 1872-7492, Vol. 223, 20-27 p.Article in journal (Refereed) Published
Abstract [en]

Nora virus is an enteric virus that causes persistent, non-pathological infection in Drosophila melanogaster. It replicates in the fly gut and is transmitted via the fecal-oral route. Nora virus has a single-stranded positive-sense RNA genome, which is translated in four open reading frames. Reading frame three encodes the VP3 protein, the structure and function of which we have investigated in this work. We have shown that VP3 is a trimer that has an α-helical secondary structure, with a functionally important coiled-coil domain. In order to identify the role of VP3 in the Nora virus life cycle, we constructed VP3-mutants using the cDNA clone of the virus. Our results show that VP3 does not have a role in the actual assembly of the virus particles, but virions that lack VP3 or harbor VP3 with a disrupted coiled coil domain are incapable of transmission via the fecal-oral route. Removing the region downstream of the putative coiled coil appears to have an effect on the fitness of the virus but does not hamper its replication or transmission. We also found that the VP3 protein and particularly the coiled coil domain are crucial for the stability of Nora virus virions when exposed to heat or proteases. Hence, we propose that VP3 is imperative to Nora virus virions as it confers stability to the viral capsid.

Place, publisher, year, edition, pages
Elsevier, 2016
Keyword
RNA viruses, Nora virus, Capsid stability, Virus biology
National Category
Immunology in the medical area
Identifiers
urn:nbn:se:umu:diva-124102 (URN)10.1016/j.virusres.2016.06.011 (DOI)000383826600003 ()27329665 (PubMedID)
Available from: 2016-07-17 Created: 2016-07-17 Last updated: 2016-11-10Bibliographically approved
2. Convergent evolution of argonaute-2 slicer antagonism in two distinct insect RNA viruses
Open this publication in new window or tab >>Convergent evolution of argonaute-2 slicer antagonism in two distinct insect RNA viruses
Show others...
2012 (English)In: PLoS Pathogens, ISSN 1553-7366, E-ISSN 1553-7374, Vol. 8, no 8, e1002872Article in journal (Refereed) Published
Abstract [en]

RNA interference (RNAi) is a major antiviral pathway that shapes evolution of RNA viruses. We show here that Nora virus, a natural Drosophila pathogen, is both a target and suppressor of RNAi. We detected viral small RNAs with a signature of Dicer-2 dependent small interfering RNAs in Nora virus infected Drosophila. Furthermore, we demonstrate that the Nora virus VP1 protein contains RNAi suppressive activity in vitro and in vivo that enhances pathogenicity of recombinant Sindbis virus in an RNAi dependent manner. Nora virus VP1 and the viral suppressor of RNAi of Cricket paralysis virus (1A) antagonized Argonaute-2 (AGO2) Slicer activity of RNA induced silencing complexes pre-loaded with a methylated single-stranded guide strand. The convergent evolution of AGO2 suppression in two unrelated insect RNA viruses highlights the importance of AGO2 in antiviral defense.

National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-61306 (URN)10.1371/journal.ppat.1002872 (DOI)000308558000047 ()22916019 (PubMedID)
Available from: 2012-11-08 Created: 2012-11-08 Last updated: 2016-11-10Bibliographically approved
3. The N-terminus of Nora virus is important for virion assembly
Open this publication in new window or tab >>The N-terminus of Nora virus is important for virion assembly
(English)Manuscript (preprint) (Other academic)
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-127349 (URN)
Available from: 2016-11-09 Created: 2016-11-09 Last updated: 2016-11-09
4. Drosophila melanogaster transcriptional response to Nora virus infection
Open this publication in new window or tab >>Drosophila melanogaster transcriptional response to Nora virus infection
(English)Manuscript (preprint) (Other academic)
National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:umu:diva-127350 (URN)
Available from: 2016-11-09 Created: 2016-11-09 Last updated: 2016-11-09

Open Access in DiVA

fulltext(1054 kB)65 downloads
File information
File name FULLTEXT01.pdfFile size 1054 kBChecksum SHA-512
c5fa1a33d37eea6ddd5309648d48170fdceb9001d2afdb94d92fe22ef8d33336c2b78a39ebf7a1e897ea7aab93f2926d53e52c701ceeb9bb1d43ab28bfbb7425
Type fulltextMimetype application/pdf
spikblad(113 kB)21 downloads
File information
File name SPIKBLAD01.pdfFile size 113 kBChecksum SHA-512
eba29331e1a78593130fed5e15ed0152ad071a179af793aac806cbba8e6b412e5983634c4f6499c2d19738b4abe0855b25a537e0cb7f6c62534dcbbdc4043b20
Type spikbladMimetype application/pdf

Search in DiVA

By author/editor
Sadanandan, Sajna Anand
By organisation
Department of Molecular Biology (Faculty of Medicine)
Cell and Molecular Biology

Search outside of DiVA

GoogleGoogle Scholar
Total: 65 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 68 hits
ReferencesLink to record
Permanent link

Direct link