Global Transcriptional Profile of Tranosema rostrale Ichnovirus Genes in Infected Lepidopteran Hosts and Wasp Ovaries  

作　　者：Asieh Rasoolizadeh Frédéric Dallaire Don Stewart Catherine Béliveau Renée Lapointe Michel Cusson 

机构地区：[1]Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du PEPS, P.O. Box 10380, Stn. Ste-Foy, Québec, QC, G1V 4C7, Canada [2]Département de biologie, Université Laval, Québec, QC, G1V 0A6, Canada [3]Département de biochimie et microbiologie, Université Laval, Québec, QC, G1V 0A6, Canada

出　　处：《Virologica Sinica》2009年第5期478-492,共15页中国病毒学（英文版）

基　　金：Grants from the Canadian Forest Service(CFS) and a Discovery grant from the Natural Sciences and Engineering Research Council of Canada to MC

摘　　要：The ichnovirus TrIV, transmitted by the endoparasitic wasp Tranosema rostrale to its lepidopteran host during oviposition, replicates asymptomatically in wasp ovaries and causes physiological dysfunctions in parasitized caterpillars. The need to identify ichnoviral genes responsible for disturbances induced in lepidopteran hosts has provided the impetus for the sequencing and annotation of ichnovirus genomes, including that of TrIV. In the latter, 86 putative genes were identified, including 35 that could be assigned to recognized ichnoviral gene families. With the aim of assessing the relative importance of each TrIV gene, as inferred from its level of expression, and evaluating the accuracy of the gene predictions made during genome annotation, the present study builds on an earlier qPCR quantification of transcript abundance of TrIV rep ORFs, in both lepidopteran and wasp hosts, extending it to other gene families as well as to a sample of unassigned ORFs. We show that the majority (91%) of putative ORFs assigned to known gene families are expressed in infected larvae, while this proportion is lower (67%) for a sample taken among the remaining ORFs. Selected members of the TrV and rep gene families are shown to be transcribed in infected larvae at much higher levels than genes from any other TrIV gene family, pointing to their likely involvement in host subjugation. In wasp ovaries, the transcriptional profile is dominated by a rep gene and a member of a newly described gene family encoding secreted proteins displaying a novel cysteine motif, which we identified among previously unassigned ORFs.The ichnovirus TrIV, transmitted by the endoparasitic wasp Tranosema rostrale to its lepidopteran host during oviposition, replicates asymptomatically in wasp ovaries and causes physiological dysfunctions in parasitized caterpillars. The need to identify ichnoviral genes responsible for disturbances induced in lepidopteran hosts has provided the impetus for the sequencing and annotation of ichnovirus genomes, including that of TrIV. In the latter, 86 putative genes were identified, including 35 that could be assigned to recognized ichnoviral gene families. With the aim of assessing the relative importance of each TrIV gene, as inferred from its level of expression, and evaluating the accuracy of the gene predictions made during genome annotation, the present study builds on an earlier qPCR quantification of transcript abundance of TrIV rep ORFs, in both lepidopteran and wasp hosts, extending it to other gene families as well as to a sample of unassigned ORFs. We show that the majority （91%） of putative ORFs assigned to known gene families are expressed in infected larvae, while this proportion is lower （67%） for a sample taken among the remaining ORFs. Selected members of the TrV and rep gene families are shown to be transcribed in infected larvae at much higher levels than genes from any other TrIV gene family, pointing to their likely involvement in host subjugation. In wasp ovaries, the transcriptional profile is dominated by a rep gene and a member of a newly described gene family encoding secreted proteins displaying a novel cysteine motif, which we identified among previously unassigned ORFs.

关 键 词：POLYDNAVIRUS Ichnovirus Choristoneura fumiferana Tranosema rostrale Transcriptional analysis 

分 类 号：Q913[天文地球—古生物学与地层学]