Toxoneuron nigriceps (Viereck) (Hymenoptera, Braconidae) is an endophagous parasitoid of the tobacco budworm Heliothis virescens (F.) (Lepidoptera, Noctuidae). Parasitized H. virescens larvae are developmentally arrested and show a complex array of pathological symptoms ranging from the suppression of the immune response to an alteration of ecdysone biosynthesis and metabolism. Most of these pathological syndromes are induced by the polydnavirus associated to T. nigriceps (TnBV). An overview of our recent research work on this system is here provided. The mechanisms involved in the disruption of the host hormonal balance have been further investigated, allowing to better defining the physiological model previously proposed. A functional genomic approach has been undertaken to identify TnBV genes expressed in the host and to assess their role in the major parasitoid-induced pathologies. Some TnBV genes cloned so far are novel and do not show any similarity with genes already available in the data bases, while others code for proteins having conserved domains, such as aspartic proteases and tyrosine phosphatases. The entire TnBV genome sequencing is in progress and will considerably contribute to the understanding of the molecular bases of parasitoid-induced host alterations.
Physiological and molecular interaction in the host parasitoid system Heliothis virescens-Toxoneuron nigriceps: current status and future perspectives
Graziani F;
2004
Abstract
Toxoneuron nigriceps (Viereck) (Hymenoptera, Braconidae) is an endophagous parasitoid of the tobacco budworm Heliothis virescens (F.) (Lepidoptera, Noctuidae). Parasitized H. virescens larvae are developmentally arrested and show a complex array of pathological symptoms ranging from the suppression of the immune response to an alteration of ecdysone biosynthesis and metabolism. Most of these pathological syndromes are induced by the polydnavirus associated to T. nigriceps (TnBV). An overview of our recent research work on this system is here provided. The mechanisms involved in the disruption of the host hormonal balance have been further investigated, allowing to better defining the physiological model previously proposed. A functional genomic approach has been undertaken to identify TnBV genes expressed in the host and to assess their role in the major parasitoid-induced pathologies. Some TnBV genes cloned so far are novel and do not show any similarity with genes already available in the data bases, while others code for proteins having conserved domains, such as aspartic proteases and tyrosine phosphatases. The entire TnBV genome sequencing is in progress and will considerably contribute to the understanding of the molecular bases of parasitoid-induced host alterations.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
