This paper presents evidence that Thosea asigna virus (TaV) has a unique capsid expression strategy and is a member of the Nudaurelia beta-like genus of the Tetraviridae. Electron microscopy of TaV particles indicated a 38 nm, T = 4 icosahedral capsid similar in structure to that of Nudaurelia beta virus (NbetaV). TaV particles have a buoyant density of 1.296 g/cm3 in CsCl and consist of two capsid proteins of 56 and 6 kDa. The virus genome contains a genomic RNA molecule of 6.5 kb and a subgenomic molecule of 2.5 kb. Northern blotting of TaV RNA indicated a genomic organization similar to that of NbetaV. The capsid gene of TaV is carried on both the genomic and subgenomic RNA molecules, while the RNA polymerase gene is present only on the genomic RNA. Cloning and sequencing of the TaV capsid gene identified an open reading frame that could potentially encode a capsid precursor protein of up to 82.5 kDa. The N-terminal sequences of the capsid proteins were compared with the nucleotide sequence of the capsid open reading frame. The sequences indicate that the pre-protein is cleaved at two positions to produce the 56 and 6 kDa capsid proteins as well as a predicted third protein that was not detected in the mature virion. Phylogenetic analysis of the capsid proteins indicated that TaV is more closely related to NbetaV than to the Nudaurelia omega-like viruses. The eight beta-sheets that make up a jelly roll structure in the TaV capsid protein were identified by computer analysis.
AgrawalD. K.,
JohnsonJ. E.1992; Sequence and analysis of the capsid protein of Nudaurelia capensis o virus, an insect virus with T = 4 icosahedral symmetry. Virology 190:806–814
ChaoY. C.,
ScottH. A.,
YoungS. Y.III1983; An icosahedral RNA virus of the soybean looper (Pseudoplusia includens). Journal of General Virology 64:1835–1838
ChelvanayagamG.,
HeringaJ.,
ArgosP.1992; Anatomy and evolution of proteins displaying the viral capsid jellyroll topology. Journal of Molecular Biology 228:220–242
EntwistleP. F.1987; Virus diseases of Limacodidae. In Slug and Nettle Caterpillars: The Biology, Taxonomy and Control of the Limacodidae of Economic Importance on Palms in South East Asia 1st edn pp 213–221 Edited by
CockM. J. W.,
GodfrayH. C. J.,
HollowayJ. D.
Wallingford: C.A.B. International;
FinchJ. T.,
CrowtherR. A.,
HendryD. A.,
StruthersJ. K.1974; The structure of Nudaurelia capensis ft virus: the first example of a capsid with icosahedral surface symmetry T = 4. Journal of General Virology 24:191–200
GordonK. H. J.,
WilliamsM. R.,
HendryD. A.,
HanzlikT. N.1999; Sequence of the genomic RNA of Nudaurelia ft virus (Tetraviridae) defines a novel virus genome organization. Virology (in press)
HanzlikT. N.,
DorrianS. J.,
GordonK. H. J.,
ChristianP. D.1993; A novel small RNA virus isolated from the cotton bollworm, Helicoverpa armigera. Journal of General Virology 74:1805–1810
HanzlikT. N.,
DorrianS. J.,
JohnsonK. N.,
BrooksE. M.,
GordonK. H. J.1995; Sequence of RNA2 of the Helicoverpa armigera stunt virus (Tetraviridae) and bacterial expression of its genes. Journal of General Virology 76:799–811
HendryD. A.,
JohnsonJ. E.,
RueckertR. R.,
ScottiP. D.,
HanzlikT. N.1995; Family Tetraviridae. In Virus Taxonomy: Sixth Report of the International Committee on Taxonomy of Viruses pp 372–375 Edited by
MurphyF. A.,
FauquetC. M.,
BishopD. L.,
GhabrialS. A.,
JarvisA. W.,
MartelliG. P.,
MayoM. A.,
SummersM. D.
New York: Springer–Verlag;
HubbardM. J.1996; Abundant calcium homeostasis machinery in rat dental enamel cells. Up–regulation of calcium store proteins during enamel mineralization implicates the endoplasmic reticulum in calcium transcytosis. European Journal of Biochemistry 239:611–623
KooninE. V.,
DoljaV. V.1993; Evolution and taxonomy of positive-strand RNA viruses: implications of comparative analysis of amino acid sequences. Critical Reviews in Biochemistry and Molecular Biology 28:375–430
OlsonN. H.,
BakerT. S.,
JohnsonJ. E.,
HendryD. A.1990; The three-dimensional structure of frozen-hydrated Nudaurelia capensis ft virus, a T = 4 insect virus. Journal of Structural Biology 105:111–122
SchaggerH.,
von JagowG.1987; Tricine-sodium dodecyl sulfate polyacrylamide-gel electrophoresis for the separation of proteins in the range from 1 to 100 kDa. Analytical Biochemistry 166:368–379