Author : Prof. Venugopal Nair Head, Avian Viral Diseases Programme BBSRC Institute for Animal Health Compton Berkshire RG20 7NN, United Kingdom E-mail: email@example.com Date : 2011-10-12 Number Of Readers :838
More recently, insertional activation of small non-coding RNAs such as microRNAs have been demonstrated in neoplastic transformation by avian retroviruses (Nair, 2008; Thompson et al., 2011).
For example, development of the bacterial artificial chromosome (BAC)-based infectious clones of a number of MDV strains (Petherbridge et al., 2004; Petherbridge et al., 2003) has identified the functions of important genes such as Meq (Nair and Kung, 2004) and vTR (Jarosinski et al., 2010; Jarosinski and Osterrieder, 2010) in the induction of disease.
More recently, we have demonstrated the role of virus-encoded microRNAs in the induction of lymphomas (Zhao et al., 2011).
Although the fundamental mechanisms of this evolution are not fully known, the role of vaccines themselves in assisting the drive towards increasing virulence has not been ruled out (Nair, 2005).
If the viral evolution is allowed to continue at the present rate with the current vaccines and the vaccination strategies, MD could again emerge as a major economic problem for the industry.
Continued introduction of newer vaccines that may succeed on short-term is unlikely to be a sustainable long-term strategy.
failure to prevent the infection, replication and shedding of virulent virus strains is a serious limitation of the current vaccines.
Future research should aim at developing vaccines capable of inducing vaccines capable of inducing 'sterile immunity' that would prevent virus replication in the vaccinated hosts.
Baigent, S., Nair
, V., Currie, R., 2006, Real-timequantitative PCR for Marek's disease vaccine virusin feather samples: applications and opportunities.
ev Biol (Basel) 126, 271-281; discussion 327.
, V., 2005, Evolution of Marek's disease - A paradigmfor incessant race between the pathogen and thehost.
The Veterinary Journal 170
, V., 2008, Retrovirus-induced oncogenesis and safetyof retroviral vectors.
Curr Opin Mol Ther 10, 431-438.
, V., Kung, H.J., 2004, Marek's disease virusoncogenicity: Molecular mechanisms, In:Davison, F., Nair
, V. (Eds.) Marek's disease, anevolving problem.
Elsevier Academic Press
Petherbridge, L., Brown, A.C., Baigent, S.J., Howes, K.,Sacco, M.A., Osterrieder, N., Nair, V.K., 2004,Oncogenicity of virulent Marek's disease viruscloned as bacterial artificial chromosomes.
J Virol78, 13376-13380.
Petherbridge, L., Howes, K., Baigent, S.J., Sacco, M.A.,Evans, S., Osterrieder, N., Nair
, V., 2003,Replicationcompetentbacterial artificial chromosomes ofMarek's disease virus: Novel tools for generation ofmolecularly defined herpesvirus vaccines.
Zhao, Y., Xu, H., Yao, Y., Smith, L.P.
, Kgosana, L., Green, J.,Petherbridge, L., Baigent, S.J., Nair
, V., 2011, Criticalrole of the virus-encoded microRNA-155 ortholog inthe induction of Marek's disease lymphomas.
PLoSPathog 7, e1001305.