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RISK ASSESSMENT: FIELD RELEASE OF GENETICALLY MANIPULATED BACULOVIRUSES

Objective

BACULOVIRUSES (BVS) REPRESENT A GROUP OF DNA VIRUSES WHICH ARE EXCLUSIVE TO INSECTS AND CERTAIN CRUSTACEANS AND ARE NON-INFECTIVE IN VERTEBRATES. THEY ARE THEREFORE REGARDED AS SUITABLE FOR DEVELOPMENT AND DEPLOYMENT AS AGENTS OF PEST CONTROL. THE POSSIBILITY TO USE GENETIC ENGINEERING TO DEVELOP CUSTOM DESIGNED BVS THAT WILL ELUDE THE ACQUISITION OF RESISTANCE BY THE TARGET HOST IS ONE REASON FOR THE PROPOSED RISK ASSESSMENT RESEARCH. TO THIS END A BACULOVIRUS OF THE SUBGROUP A (INFECTING LEPIDOPTERA : NOCTUIDAE) HAS BEEN MODIFIED, INSERTING A NON-CODING SYNTHETIC OLIGONUCLEOTIDE IN THE GENOME WHICH IS NOT ALTERING GENETIC INFORMATION AND CAN BE USED AS A MARKER. THE MARKER VIRUS WILL BE TESTED ON SUSCEPTIBLE CATERPILLARS IN LABORATORY STUDIES AND RELEASED IN THE ENVIRONMENT TO INFECT LARVAE AND ASSESS THE TIME-SPACE DISTRIBUTION, INFECTION POTENTIAL AND EVOLUTION OF THE AGENT. THE EVENTUAL AIM OF THE STUDY IS TO ENGINEER INTO A BACULOVIRUS THE B. THURINGENSIS TOXIN OR OTHER GENES SO THAT IT WILL INHIBIT LARVAL DEVELOPMENT OF SPECIFIC LEPIDOPTERAN, NAMELY P. FLAMMEA, INFECTING PINE TREES. THE CONTRACTANT LABORATORY HAS A WIDE AND UNIQUE EXPERIENCE IN THE GENETIC ENGINEERING OF DNA BACULOVIRUSES AND THE PRODUCTION OF MARKER VIRUSES IS OPENING THE WAY TO THE PREPARATION OF BVS WITH DELECTED OR SUBSTITUTED POLYHEDRIN GENES WHICH WILL BE TESTED IN TISSUE AND ANIMAL CULTURE AND SUITABLE UNSTABLE VIRUSES SELECTED FOR FIELD TESTS. THE COLLABORATION WITH THE DARMSTADT LABORATORY, WHICH HAS EXTENSIVE EXPERIENCE ON THE BIOLOGY AND CONTROL OF MOTH BACULOVIRUSES, WILL BE VERY USEFUL IN ASSESSING THE PENETRATION OF MODIFIED VIRUSES IN THEIR NATURAL ENVIRONMENT.
Assessing the risk of release of a genetically engineered baculovirus depends on a sound knowledge of the ecology of the wild type from which, through cloning, it was derived. Ecological deviations in the recombinant virus can thus be identified. To give wide ecological coverage, 2 baculoviruses, each infective, one a pest of pine forest (pine beauty moth) and the other a pest of agricultural crops (cabbage moth), and a wild type (AcNPV) and its recombinant clone (AcNPV/plOZ) were studied. Extensive field observations were made to permit identification of ecological aspects suitable for study in severely contained microcosms specially developed for the purpose. The behaviour of wild type viruses and the recombinant were studied in microcosms.

The host ranges of cabbage moth and pine beauty moth NPVs covered 4 of 14 families of Lepidoptera. 4 clones of each NPV had different infectivity levels, up to 4.5 x the wild types. In the field, virus persisted in soils for at least 3 years. The main agents of local dispersal were opilionids, excreting active virus for 100 h postingestion. Birds spread virus widely; 40% of individuals and 9 of 15 species excreted active virus. Cabbage moth virus was recovered 20 km from a point of introduction. In microcosms containing field crops, simulated rain dispersed viruses. In general 1 to 10% remained on plants but the soil contained 90 to 99%; there was none in percolation water. Air flow, rain splash, parasites and aphids dispersed viruses. Despite similar levels of infectivity of wild and recombinant viruses, less recombinant virus was produced in microcosms. Recombinant virus was less persistent than the wild type.
THE PROJECT CONCERNS RISK ASSESSMENT ANALYSES OF THE RELEASE INTO THE ENVIRONMENT OF A GENETICALLY ALTERED INSECT VIRUS THAT IS USED IN THE CONTROL OF AGRICULTURAL AND FORESTS PESTS. THE VIRUS IS THE OCCLUDED BACULOVIRUS MBNPV, NATURAL HOST OF THE LEPIDOPTERAN M. BRASSICAE WHICH IS A PEST OF CABBAGE AND OTHER FIELD CROPS IN THE WESTERN PALAEARTIC. MBNPV IS CROSS INFECTIVE TO THE MOTH PANOLIS FLAMMEA, A PEST OF PINE FORESTS IN THE SAME GEOGRAPHIC AREAS. THE RISK ASSESSMENT WILL MEASURE THE PENETRATION OF THE SPATIAL, TEMPORAL AND BIOLOGICAL WORLDS FROM A SINGLE RELEASE POINT IN A FOREST SYSTEM. THE VIRUS THAT WILL BE EMPLOYED WILL CONTAIN A NON CODING OLIGONUCLEOTIDE MARKER, PERMITTING VIRUS IDENTIFICATION. THE STABILITY AND FATE OF THE MARKER VIRUS WILL BE TRACED FIRST IN A LABORATORY CONTAINED SIMULATED ECOSYSTEM, CONTAINING SMALL PINE TREES, HEATHER, GRASSES AND SOIL. VIRUS MOVEMENT FROM LEPIDOPTERANS TO PARASITOIDS AND TO OTHER TARGETS WILL BE FOLLOWED. FIELD ASSESSMENT WILL BE STUDIED BY RELEASING THE MARKER INTO HALF HECTARE OF A PINE FOREST (SCOTLAND), TRACING EVIDENCE OF MARKER VIRUS WITHIN 5 KM OF THE POINT OF INTRODUCTION. THIS PROJECT IS CONDUCTED IN COLLABORATION WITH DR. H. HUBER LABORATORY IN DARMSTADT, WHICH WILL STUDY THE PENETRATION OF THE MARKER BACULOVIRUS IN AN AGRICULTURAL SYSTEM.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

NATURAL ENVIRONMENT RESEARCH COUNCIL
Address
North Star Avenue, Polaris House
SN2 1EU Swindon
United Kingdom

Participants (1)

FEDERAL BIOLOGICAL RESEARCH CENTRE FOR AGRICULTURE AND FORESTRY (BBA)
Germany
Address
Heinrichstrasse 243
64287 Darmstadt