3.3 Viruses
3.3.1 PBC 222: Viruses for Biological Control
| Programme Title: | Viruses for Biological Control |
| Programme Leader: | Tao Zheng |
| Institution: | AgResearch |
Programme Goal: To isolate, characterise and genetically manipulate possum viruses for the biological control of possums
Rationale: Viruses could play a central role in biological control of possums acting either as a pathogen or more probably as a transmissible vector for the immunosterilisation vaccines or the delivery of bioactive proteins. Biological control strategies for possums will only be used if they have definite advantages over existing control strategies such as poisoning. These advantages may include greater coverage of the possum population, increased specificity and greater cost-effectiveness. A biological control strategy based on the use of a transmissible virus as a vector has the potential to be more cost-effective than existing possum control measures.
Herpes viruses would be ideal candidates to serve as a virus vector, because they are large viruses that can accommodate foreign genes and are highly transmissible. Many herpes viruses are sexually transmitted which could boost antibody titres at mating and they frequently establish of latent infections. These viruses are generally easy to propagate in cell culture, which is important for development of a virus vector. Electron microscopic evidence has identified herpes virus-like particles in faecal samples of possums from New Zealand. Serological evidence from our laboratory has shown that there are antibodies against herpes virus antigens in possums in New Zealand, but there are regional differences in the prevalence of these antibodies. In this project we propose to screen possums from several different regions of New Zealand for antibodies to herpes viruses. Sero-positive possums would be treated with corticosteroids to reactivate a latent infection and swabs and tissues collected from these animals for isolation of viruses. Several new possum primary cell lines have recently been established to facilitate the isolation of viruses from possums.
Viruses of wallabies may prove to be useful for the biological control of possums in New Zealand because wallabies are closely related to possums and there is a high chance that viruses isolated from wallabies will also infect possums. There is the added advantage that often viruses, which can infect a closely related species, may be more pathogenic in this species than in the original host such as infection of myxoma virus in American and European rabbits. At least ten strains of macropodid herpesviruses (MaHV) have been isolated from Australian marsupials. Furthermore, the use of viruses isolated from New Zealand wallabies eliminates the difficulties associated with obtaining permission from ERMA for the importation of new organisms. This second part of this project proposes to isolate viruses from immune compromised dama, parma and Bennett's wallabies from Kawau Island (Auckland) and Canterbury.
Objective 1
Objective Title: Viruses for possum biological control
Research Leader: Dr T. Zheng
Description:
The goal of this programme is to isolate viruses from possums and wallabies and assess their usefulness for the biological control of possums. Herpesviruses have many desirable characteristics for use as a virus vector for a biological control strategy and technologies have been developed over the past two years, which will facilitate the isolation of herpesviruses from possums. In the 2001/02-year, possums will be trapped from areas with a high prevalence of antibodies against herpes virus. Possums with antibodies to herpes virus will be treated with corticosteroids to reactivate viral infections and various swabs and tissues from these animals will be cultured for viruses. In the second part of the objective, attempts will be made to isolate viruses from wallabies. Viruses of wallabies may prove to be useful for the biological control of possums in New Zealand as wallabies are closely related to possums and there is a high chance that viruses isolated from wallabies will also infect possums. Wallabies from Kawau Island and the Canterbury region will be trapped or shot. Serum samples from these animals will be collected and tested for antibodies to herpesviruses. A proportion of the trapped animals will be treated with corticosteroids and subsequently, swab and tissue samples collected for virus isolation.
Contact for Enquiries
Farm Monitoring Programme Manager
Monitoring and Evaluation
MAF Policy
PO Box 2526
Wellington
NEW ZEALAND
Phone: +64 4 894 0623
Fax: +64 4 894 0741
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