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United States Department of Agriculture

Agricultural Research Service

Related Topics

Research Project: IMPROVEMENT OF UV RESISTANCE, VIRAL AND HOST RANGE ENHANCEMENT OF BACULOVIRUSES AS BIOCONTROL AGENTS

Location: Biological Control of Insects Research

2007 Annual Report


1a.Objectives (from AD-416)
Genetically engineer specific fluorescent protein genes into baculoviruses that will be expressed in the envelopes of budded virus and occlusion bodies to serve as barriers against ultraviolet inactivation. Incorporate specific proteins into polyhedra (occlusion bodies) of baculoviruses by a genetic fusion process that would lead to early mortality or inhibit feeding of pest insects. Examine the basis of baculovirus resistance at the cellular level employing cell culture methodology in order to better understand the nature of baculovirus host range.


1b.Approach (from AD-416)
This proposal employs a molecular approach whereby baculoviruses will be stabilized against inactivation by ultraviolet light (UV) as well as to make them faster acting. To achieve these goals, several fluorescent protein genes will be engineered into baculovirus genomes which when expressed in the envelopes of the viral particles and occlusion bodies will provide protection against inactivation by UV light. This methodology is designed to reduce damage to the viral DNA of baculoviruses. To make the bacuoviruses faster acting, specific proteins will be incorporated into occlusion bodies of baculoviruses by a genetic fusion process that will lead to early mortality or inhibit feeding by pest insects since viral replication in the host is not a pre requisite for elaboration of the active proteins. This research project will also examine the nature of baculovirus resistance at the cellular level employing insect cell lines that are refractile to baculoviruses. Recombinants with fluorescent markers under various promoters will elucidate where the block occurs and thus provide knowledge that could be valuable in understanding viral host range.


4.Accomplishments
Early detection of Baculoviruses in Susceptible Hosts. One of the disadvantages in employing baculoviruses as biological control agents for economically important pests is that it takes several days before it is known whether or not the insect is infected and by this time considerable crop damage could have occurred. This is due to the normally slow replication of most viruses in their hosts. A baculovirus was developed that carried a fluorescent marker expressed early after infecting the host by feeding on contaminated surfaces. Infection could be monitored by examining the caterpillar (larva) under UV light as infected larvae fluoresced under these conditions. Detection of infected larvae could be demonstrated within 24 hours providing a useful tool for determining early infection. This technique can provide a reliable means for determining the infection of larvae in the field exposed to baculoviruses and will provide greater confidence to farmers that the biological control agent employed is working satisfactorily.

The findings demonstrated in the above accomplishment are consistent with and supportive of goals set out in the National Program Action Plan 304 and as such is part of the program component for Development of New and Improved Pest Control Technologies, "particularly biologically-based methods”.

Isolation and Characterization of a New Baculovirus. Following the discovery of a typical baculovirus infection in cabbage looper larvae that were used to propagate insect parasites, it was of interest to determine if this was a new baculovirus. The baculovirus isolated from cabbage looper larvae was proven to be a new virus. The baculovirus, although related to another baculovirus, which infects the celery looper proved to be very infectious for a number of insect pests of agricultural importance. Since baculoviruses are the viral agents of choice for the control of insect pests of field and vegetable crops as well as forests, this discovery is a very important finding for the potential control of pests of agricultural significance.

The findings demonstrated in the above accomplishment are consistent with and supportive of goals set out in the National Program Action Plan 304 and as such is part of the program component for Development of New and Improved Pest Control Technologies, "particularly biologically-based methods”.


5.Significant Activities that Support Special Target Populations
None


6.Technology Transfer

Number of new CRADAs and MTAs1

Review Publications
McIntosh, A.H., Grasela, J.J., Ignoffo, C.M. 2007. In vitro host range of the Hz-1 non-occluded virus in arthropod cell lines. In Vitro Cellular and Developmental Biology. Available: http://dx.doi.org/10.1007/s11626-007-9032-6.

Habibi, J., Goodman, C.L., Stuart, M.K. 2006. Distribution of elongation factor-1alpha in larval tissues of the fall armyworm, Spodoptera frugiperda. Journal of Insect Science. 6:32.

Last Modified: 9/10/2014
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