The endoparasitic wasp Tranosema rostrale transmits an ichnovirus to its lepidopteran host, Choristoneura fumiferana, during parasitization. As shown for other ichnoviruses, the segmented dsDNA genome of the T. rostrale ichnovirus (TrIV) features several multi-gene families, including the repeat element (rep) family, whose products display no known similarity to non-ichnovirus proteins, except for a homologue encoded by the genome of the Helicoverpa armigera granulovirus; their functions remain unknown. This study applied linear regression of efficiency analysis to real-time PCR quantification of transcript abundance for all 17 TrIV rep open reading frames (ORFs) in parasitized and virus-injected C. fumiferana larvae, as well as in T. rostrale ovaries and head–thorax complexes. Although transcripts were detected for most rep ORFs in infected caterpillars, two of them clearly outnumbered the others in whole larvae, with a tendency for levels to drop over time after infection. The genome segments bearing the three most highly expressed rep genes in parasitized caterpillars were present in higher proportions than other rep-bearing genome segments in TrIV DNA, suggesting a possible role for gene dosage in the regulation of transcription level. TrIV rep genes also showed important differences in the relative abundance of their transcripts in specific tissues (cuticular epithelium, the fat body, haemocytes and the midgut), implying tissue-specific roles for individual members of this gene family. Significantly, no rep transcripts were detected in T. rostrale head–thorax complexes, whereas some were abundant in ovaries. There, the transcription pattern was completely different from that observed in infected caterpillars, suggesting that some rep genes have wasp-specific functions.
BéliveauC.,
LaforgeM.,
CussonM.,
BellemareG.2000; Expression of a Tranosema rostrale polydnavirus gene in the spruce budworm, Choristoneura fumiferana . J Gen Virol 81:1871–1880
BéliveauC.,
LevasseurA.,
StoltzD.,
CussonM.2003; Three related TrIV genes: comparative sequence analysis and expression in host larvae and Cf-124T cells. J Insect Physiol 49:501–511[CrossRef]
CussonM.,
BarronJ. R.,
GouletH.,
RégnièreJ.,
DoucetD.1998; Biology and status of Tranosema rostrale rostrale ( Hymenoptera : Ichneumonidae ),a parasitoid of the eastern spruce budworm ( Lepidoptera : Tortricidae ). Ann Entomol Soc Am 91:87–93[CrossRef]
DoucetD.,
CussonM.1996a; Alteration of developmental rate and growth of Choristoneura fumiferana parasitized by Tranosema rostrale : role of the calyx fluid. Entomol Exp Appl 81:21–30[CrossRef]
DoucetD.,
CussonM.1996b; Role of calyx fluid in alterations of immunity in Choristoneura fumiferana larvae parasitized by Tranosema rostrale . Comp Biochem Physiol 114:311–317[CrossRef]
DoucetD.,
LevasseurA.,
BéliveauC.,
LapointeR.,
StoltzD.,
CussonM.2007; In vitro integration of an ichnovirus genome segment into the genomic DNA of lepidopteran cells. J Gen Virol 88:105–113[CrossRef]
FalabellaP.,
VarricchioP.,
ProvostB.,
EspagneE.,
FerrareseR.,
GrimaldiA.,
EguileorM.,
FimianiG.,
UrsiniM. V.other authors2007; Characterization of the I κ B-like gene family in polydnaviruses associated with wasps belonging to different braconid subfamilies. J Gen Virol 88:92–104[CrossRef]
GalibertL.,
DevauchelleG.,
CousseransF.,
RocherJ.,
CéruttiP.,
Barat-HouariM.,
FournierP.,
VolkoffA. N.2006; Members of the Hyposoter didymator ichnovirus repeat element gene family are differentially expressed in Spodoptera frugiperda . Virol J 3:48[CrossRef]
Gundersen-RindalD. E.,
PedroniM. J.2006; Characterization and transcriptional analysis of protein tyrosine phosphatase genes and an ankyrin repeat gene of the parasitoid Glyptapanteles indiensis polydnavirus in the parasitized host. J Gen Virol 87:311–322[CrossRef]
HarrisonR. L.,
PophamH. J. R.2008; Genomic sequence analysis of a granulovirus isolated from the Old World bollworm, Helicoverpa armigera . Virus Genes 36:565–581[CrossRef]
IbrahimA. M.,
ChoiJ. Y.,
JeY. H.,
KimY.2007; Protein tyrosine phosphatases encoded in Cotesia plutellae bracovirus: sequence analysis, expression profile, and a possible biological role in host immunosuppression. Dev Comp Immunol 31:978–990[CrossRef]
KroemerJ. A.,
WebbB. A.2004; Polydnavirus genes and genomes: emerging gene families and new insights into polydnavirus replication. Annu Rev Entomol 49:431–456[CrossRef]
KroemerJ. A.,
WebbB. A.2005; I κ B-related vankyrin genes in the Campoletis sonorensis ichnovirus: temporal and tissue-specific patterns of expression in parasitized Heliothis virescens lepidopteran hosts. J Virol 79:7617–7628[CrossRef]
MartiD.,
Grossniklaus-BürginC.,
WyderS.,
WylerT.,
LanzreinB.2003; Ovary development and polydnavirus morphogenesis in the parasitic wasp Chelonus inanitus . I. Ovary morphogenesis, amplification of viral DNA and ecdysteroid titres. J Gen Virol 84:1141–1150[CrossRef]
ProvostB.,
VarricchioP.,
AranaE.,
EspagneE.,
FalabellaP.,
HuguetE.,
La ScaleiaR.,
CattolicoL.,
PoiriéM.other authors2004; Bracoviruses contain a large multigene family coding for protein tyrosine phosphatases. J Virol 78:13090–13103[CrossRef]
RutledgeR. G.,
StewartD.2008a; A kinetic-based sigmoidal model for the polymerase chain reaction and its application to high-capacity absolute quantitative real-time PCR. BMC Biotechnol 8:47[CrossRef]
RutledgeR. G.,
StewartD.2008b; Critical evaluation of methods used to determine amplification efficiency refutes the exponential character of real-time PCR. BMC Mol Biol 9:96[CrossRef]
StoltzD. B.1993; The polydnavirus life cycle. In Parasites and pathogens of insects . vol 1 pp 80–101Edited byBeckageN. E.,
ThompsonS. N.,
FedericiB. A.
San Diego, CA: Academic Press;
StoltzD. B.,
GuzoD.,
CookD.1986; Studies on polydnavirus transmission. Virology 155:120–131[CrossRef]
TanakaK.,
LapointeR.,
BarneyW. E.,
MakkayA. M.,
StoltzD.,
CussonM.,
WebbB. A.2007; Shared and species-specific features among ichnovirus genomes. Virology 363:26–35[CrossRef]
TheilmannD. A.,
SummersM. D.1987; Physical analysis of the Campoletis sonorensis virus multipartite genome and identification of a family of tandemly repeated elements. J Virol 61:2589–2598
TheilmannD. A.,
SummersM. D.1988; Identification and comparison of Campoletis sonorensis virus transcripts expressed from four genomic segments in the insect hosts Campoletis sonorensis and Heliothis virescens . Virology 167:329–341
ThoetkiattikulH.,
BeckM. H.,
StrandM. R.2005; Inhibitor κ B-like proteins from a polydnavirus inhibit NF- κ B activation and suppress the insect immune response. Proc Natl Acad Sci U S A 102:11426–11431[CrossRef]
ThompsonJ. D.,
GibsonT. J.,
PlewniakF.,
JeanmouginF.,
HigginsD. G.1997; The clustal_x windows interface: flexible strategies for multiple sequence alignment aided by quality analysis tools. Nucleic Acids Res 25:4876–4882[CrossRef]
WangZ.,
SpadoroJ.1998; Determination of target copy number of quantitative standards used in PCR-based diagnostic assays. In Gene quantification pp 31–43Edited byFerré.
Boston: Birkhäuser;
WebbB. A.,
StrandM. R.,
DickeyS. E.,
BeckM. H.,
HilgarthR. S.,
BarneyW. E.,
KadashK.,
KroemerJ. A.,
LindstromK. G.,
& other authorsF.
2006; Polydnavirus genomes reflect their dual roles as mutualists and pathogens. Virology 347:160–174[CrossRef]