Molecular and biological studies of fast and slow killing granuloviruses
Wormleaton, Sally Louise (2000) Molecular and biological studies of fast and slow killing granuloviruses. PhD thesis, University of Warwick.
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Official URL: http://webcat.warwick.ac.uk/record=b1371049~S15
The aim of this project was to examine the relationship between granuloviruses (GVs)
and factors or genes governing host range, speed of kill and tissue tropism.
Hybridisations performed between "fast-killing" (fast) and "slow-killing" (slow) GVs
showed that fast GVs appeared to be closely related, as did slow GVs. Fast GVs
showed low DNA similarity and only partial collinearity to slow GVs. The exception
was Adoxophyes orana GV (AoGV), which is a slow GV but showed relatively high
DNA similarity and collinearity to fast GVs. This implied that the differences in
speed of kill were not necessarily due to the large variations within the genome
between fast and slow GVs. Dose and time mortality studies were performed using
AoGV and the genome was physically mapped. This would allow easier access to
areas of interest on the genome such as regions that did not hybridise to other GVs,
that could be unique to AoGV, and would allow the initiation of a sequencing project
of the whole genome. The granulin-containing area of the genome was sequenced for
comparisons to other GVs. From these data, it is proposed that the relatedness of GVs
is dependent on the family of Lepidoptera they infect rather than the tissue tropism of
the virus or its speed of kill.
An attempt to expand the host range of Cryptophlebia leucotreta GV (C1GV), to
include Cydia pomonella, was undertaken by recombination with Cydia pomonella
GV (CpGV). In one experiment C1GV replication was rescued in C. pomonella cells.
This was either by complementation of the genome by CpGV or recombination with a
gene or factor involving host range and will require further studies to identify the
Any recombinant GVs need to be assessed thoroughly for possible expansion of host
range to non-target insects. Therefore, transfer vectors were constructed for the
production of recombinant GVs containing a reporter gene (lacZ). A recombinant
CpGV expressing ß-galactosidase was produced and will need to be cloned before
further work is performed. The course of CpGV infection in hosts differing in
permissivity to CpGV could also be studied using these recombinant viruses.
Another part of this research investigated speed of kill. It involved the study of a 2.45
kbp region in CpGV-M1, which was not present in the genotype CpGV-R3. CpGVM1
is faster killing than CpGV-R3. A recombinant CpGV-R3 that contained this
extra region from CpGV-Ml was produced and was compared to CpGV-R3 and
CpGV-M1 by bioassay to assess its speed of kill. The speed of kill was not increased
indicating that this region was not responsible. However, the study revealed some
putative origins of replication of the CpGV genome.
|Item Type:||Thesis or Dissertation (PhD)|
|Subjects:||Q Science > QR Microbiology|
|Library of Congress Subject Headings (LCSH):||Baculoviruses -- Genetics, Cryptophlebia leucotreta -- Viruses, Codling moth -- Viruses, Host-virus relationships|
|Official Date:||May 2000|
|Institution:||University of Warwick|
|Theses Department:||Warwick HRI|
|Supervisor(s)/Advisor:||Winstanley, Doreen ; Leppard, Keith|
|Sponsors:||Biotechnology and Biological Sciences Research Council (Great Britain) (BBSRC)|
|Extent:||xiv, 275 p.|
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