Transcriptional Profiles Of Cotesia Vestalis Bracovirus Genes In Plutella Xylostella Larvae

Cotesia vestalis is an endoparasitoid of larval stages of the diamondback moth Plutella xylostella. For successful parasitization, this parasitoid injects a polydnavirus, Cotesia vestalis Bracovirus (CvBV) into its host during oviposition, which can suppress the immune responses and disrupt the development of the host to create an environment favorable for the development of the parasitoid. In this thesis, we verified65CvBV genes from the parasitized P. xylostella larvae. Then we cloned17CvBV genes and analyzed the expression patterns of38CvBV genes. The results are summarized as follows:1. After comparing the CvBV genome and parasitized P. xylostella transcriptome,75CvBV genes were identified. The sizes of the genes range from300to1940bp. They encoded7gene families, including protein tyrosine phosphatase (PTP), BEN domain-coding proteins, Ankyrin, Lectin, P94-like, CrVl-like and Histone. And there were26new PDV genes which were designated as Hypothetical protein or Conserved hypothetical protein based on their homologous sequences.2. Using reverse transcript PCR,64CvBV genes were verified. PTP is the largest family with27members. BEN domain-coding protein is the second largest one with6members. Lectin and P94-like contain2members respectively. Ankyrin and CrV1-like are the smallest families with only one member. There are also16other Hypothetical proteins and9Conserved hypothetical proteins.3. The full cDNA sequences of17CvBV genes were obtained using Rapid Amplification of cDNA Ends (RACE). They were designated as c3-3, c4-6, c6-2, c6-5, c6-6, c7-7, c9-1, c12-4, c12-6, c12-9, c14-1, c15-2, c24-8, c28-1, c28-5, c29-7and c30-1. The full cDNA sequences consisted of open reading frames encoding107,252,304,320,304,238,259,300,297,287,323,340,252,277,312,526and82amino acid residues respectively. The results of sequence analyses predicted that the c3-3, c7-7and c15-2contained signal peptides. The bioinformatics analysis of the9PTP genes with full-length DNA sequecne showed that7of them were true PTP with enzyme activity.4. To determine the transcriptional profiles of CvBV genes in the parasitized P. xylostella, the total RNAs were isolated from brain, hemocyte and midgut of the host larvae parasitized by C. vestalis at12h,48h and120h post-parasitization (p.p.).The qRT-PCR analyses showed that the transcripts of all these CvBV genes were mainly detected in hemocyte, and three different patterns of the transcriptional levels were observed:(1) some genes, such as c3-3, c6-6, c6-7, c12-9, c13-1, c14-1, c16-1, c18-1, c22-1, c24-8, c27-2and c28-6, increased at first and went down afterwards;(2) c4-1,c4-3,c4-6, c6-2, c9-1,c12-6, c17-1, c27-1and c28-1continued to increase and reached the peak at120h p.p.; and (3) c5-3, c7-7, c10-1, c12-3, c15-2, c21-3, c23-1, c23-3, c23-4, c26-2, c26-4, c29-6and c34-1decreased from the beginning.