|Sun, Aijun -|
|Khan, Owais -|
|Lupiani, Blanca -|
|Reddy, Sanjay -|
Submitted to: Avian Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 3, 2013
Publication Date: January 14, 2013
Repository URL: http://handle.nal.usda.gov/10113/56950
Citation: Sun, A., Lee, L.F., Khan, O., Heidari, M., Zhang, H., Lupiani, B., Reddy, S. 2013. Deletion of Marek’s disease virus large subunit of ribonucleotide reductase (RR) impairs virus growth in vitro and in vivo. Avian Diseases. 57(2):464-468. Interpretive Summary: Mark’s disease virus (MDV), is the causative agent of Marek’s disease (MD), a cancer-like disease in chickens. We have recently identified a MDV gene named ribonucleotide reductase (RR)that may be critical for the pathogenesis of the disease. Using recombinant DNA technology we have generated a mutant MDV (Md5'RR1) in which RR1 gene was deleted. The biological characteristics of Md5'RR1 virus was studied in chickens and showed that deletion of RR in Md5 virus rendered the virus non-pathogenic and did not induce MD in birds. This mutant virus was impaired for its ability to replicate in chickens indicating that RR is essential for replication of the virus in chickens. Protection studies in chickens indicated that Md5'RR1 virus is not a candidate vaccine for MD. These findings are important knowledge to scientists for further studies on mechanisms involved in MDV replication in chickens.
Technical Abstract: Marek’s disease virus (MDV), a highly cell-associated lymphotropic alphaherpesvirus, is the causative agent of a neoplastic disease in domestic chickens, called Marek’s disease (MD). In the unique long region of the MDV genome, open reading frames UL39 and UL40 encode the large and small subunits of ribonucleotide reductase (RR) enzyme, named RR1 and RR2, respectively. MDV RR is distinguishable from that present from chicken and duck cells by monoclonal antibody T81. Using recombinant DNA technology we have generated a mutant MDV (Md5'RR1) in which RR1 was deleted. PCR amplification of RR gene in rMd5'RR1-infected DEF confirmed the deletion of 2.4 Kb RR1 with a resultant amplicon of a 640-bp fragment. Restriction enzyme digests with SalI confirmed UL39 deletion and absence of rearrangement. The biological characteristics of Md5'RR1 virus was studied in vitro and in vivo. The Md5'RR1 replicated in duck embryonic fibroblasts but significantly slower than that of parental Md5BAC, suggesting that RR is required but not essential for replication in fibroblasts. In vivo studies, however, showed that RR1 deletion virus was impaired for its ability to replicate in chickens. Inoculation of SPF chickens with Md5'RR1 showed the mutant virus is non-pathogenic and does not induce MD in birds. A revertant virus, Md5'RR1/R, was generated with the restored phenotype of the parental Md5-BAC in vivo, indicating that RR is essential for replication of the virus in chickens. Protection studies in SPF chickens indicated that Md5'RR1 virus is not a candidate vaccine for MD.