REBACHA · Host Response to Baculovirus infection in Helicoverpa armigera
FP6 — Marie Curie Actions (Human Resources and Mobility)
- Duration
- 2007-08-01 → 2009-07-31
- EU contribution
- €145,232
- Participants
- 1
- Scheme
- EIF
Lines connect the coordinator with its partners.
Results in brief
Final Activity Report Summary - REBACHA (Host Response to Baculovirus infection in Helicoverpa armigera)
Baculoviruses are large DNA viruses infecting invertebrates, mainly insects from the orders Lepidoptera, Hymenoptera and Diptera. They are used to control insect pests replacing chemical insecticides. The main limitations of baculovirus wide use are a long time they need to stop the larvae feeding as well as their high specificity towards insect species. Much research effort have been undertaken to overcome these limitations. Introducing in baculovirus genome foreign genes coding for toxins, hormones or enzymes is one of the strategies used to improve their characteristics as bioinsecticide. In the present project we aimed to identify host genes involved in the response to baculovirus infection and explored the possibility of employing these genes to improve baculovirus infectivity. Among the genes regulated after baculovirus (HearNPV) infection in Helicoverpa armigera larvae we identified a midgut protein, HaCDA5a that showed a homology to chitin deacetylase-like protein. HaCDA5a was shown to strongly bind chitin as well as to increase peritrophic membrane (PM) permeability. Bioassays showed that administered orally NPV expressing HaCDA5a is more virulent that the virus non-expressing this protein however there was no change in virulence when both viruses were injected intrahemocoelically. These findings showed that HaCDA5a most likely acts on PM while the virus enters the midgut and revealed the possibility of baculovirus improvement by expression of the host genes. Another gene that was identified to be involved in the midgut response to baculovirus infection was cellular repressor of E1A stimulated genes (creg). Up to date no CREG-like proteins have been characterized from insects. H. armigera creg showed around 30% similarity to human creg and around 70% similarity to other lepidopteran cregs. Its up-regulation due to baculovirus infection has been shown by means of real-time RT-PCR in H. armigera larvae and H. armigera derived cells, HzAM1 and HzGUT. A virus was constructed expressing Ha-creg. Bioassays showed as expected that creg-expressing virus caused lower mortality in larvae when compared to mortality of the virus non-expressing this protein. We expect that up-regulation of creg in larvae infected with the virus may form a part of response to the infection by inhibiting cell growth and hence diminishing virus replication. Its silencing by RNA interference is planned. Obtained results add to the general knowledge of host genes involved in the insect response to the pathogens as well as reveal that this knowledge can successfully be employed for improving virus characteristics for use in biocontrol.
Data: CORDIS, © European Union
Project objective
Baculoviruses are large, double-stranded DNA viruses infecting invertebrates, mostly insects from the family Lepidoptera. They cause epizootics in pest insects and thus are regarded as promising alternatives for hazardous chemical insecticides.The application of baculoviruses; however has not yet met its potential mainly due to their relatively slow speed of action and narrow spectrum of action. Different approaches are currently undertaken to improve baculovirus pathogenicity, i.e. chemical or biological additives, genetic modifications.In contrast to previous studies focused on understanding the role of the viral genes in the infection, the main objective of the proposed project is to identify and characterise insect genes involved in the response to baculovirus infection in the mid-gut of Helicoverpa armigera.Studies will be focused on the host defence mechanisms occurring in the mid-gut cells during the first step of the infection (primary infection), which is a determinant of the successful infection. Suppression subtractive hybridisation (SSH) and Quantitative-PCR technologies will be used for the selection of mid-gut genes that are regulated in the host response.Relevant genes will be characterized and recombinant baculoviruses altering the express ion of those genes will be constructed in order to determine their role in the infection process.Recombinant baculoviruses will be also evaluated in terms of dose and time to kill. Results from proposed project will be useful for a better understanding of the insect-pathogen interactions and could be interesting for the design of new baculovirus with higher speed of action and/or broader host range.Additionally, identification of genes involved in response to baculovirus could target genes candidate to be responsible for the possible development of resistance to baculovirus and further help to delay the appearance of resistance in the field by monitoring their frequency in the field populations.
Original text from CORDIS.
Participants
- UNIVERSITAT DE VALENCIA · BURJASOTCoordinatorSpain
Links
Data: CORDIS, © European Union