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Title: Inhibition of avian tumor viruses by vector-based RNA interference

item CHEN, MO
item Hunt, Henry
item Zhang, Huanmin

Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: 10/3/2007
Publication Date: 1/12/2008
Citation: Chen, M., Payne, W.S., Hunt, H.D., Zhang, H., Holmen, S.L., Dodgson, J.B. 2008. Inhibition of avian tumor viruses by vector-based RNA interference [abstract]. Plant and Animal Genome Conference. p. 257.

Interpretive Summary:

Technical Abstract: RNA interference (RNAi) has been shown to reduce the replication of certain animal viruses both in cell culture and in live animals. We developed RNAi-based anti-viral strategies against two important chicken pathogens: avian leukosis virus (ALV) and Marek’s Disease virus MDV). Entry plasmids containing RNAi cassettes with structures similar to natural chicken primary microRNAs have been developed that can contain up to three target sequences simultaneously and easily can be moved into retroviral delivery vectors (RCAS). We showed that RNAi against the subgroup (B) ALV envelope gene (env(B)) and its host receptor gene (tvb) significantly reduced mRNA expression, protein expression and susceptibility to ALV(B) infection in cell culture. We demonstrated the specificity of antiviral RNAi using vectors with a doxycycline-regulated promoter. We further showed that retroviral based RNAi vectors can significantly inhibit the replication of MDV, both serotypes I and III, in cell culture. Retroviral vector-delivered RNAi targeting the viral glycoprotein gB gene and the ICP-4 gene reduced MDV titers and plaque size significantly. Other viral genes, such as UL49, are now being tested as targets. We are in the process of testing antiviral RNAi in birds into which the retroviral vectors have been introduced in the newly laid embryo, followed by incubation, hatching and challenge with virulent MDV. Viral replication is followed by titering and serology at various stages. Pathogenic effects of the virus are monitored throughout. Preliminary results suggest that retroviral vector-based RNAi may reduce MDV replication in lytic stage-infected birds.