Progress 02/15/03 to 02/14/06

Outputs
Marek's Disease virus (MDV) was shown to encode a gene responsible for cancer like disease in chickens. This gene is called Meq and has homology to other transcriptional factors encoded by chickens. We have made a Marek's disease mutant virus in which we disrupted the gene coding the Meq protein. This recombinant was shown to replicate efficiently in chickens, so we have applied for a US patent. We have shown that this recombinant virus is able to replicate efficiently in chickens during early cytolytic infection, but was defective in reactivation as seen by failure of recovery of virus from lymphocytes by co cultivation with chicken embryonic fibroblasts 2 weeks post infection. Further evaluation showed that mutant virus was unable to control early cytolytic infection as shown by atrophy of lymphoid organs. This recombinant virus was used as a vaccine to protect chickens against highly virulent strains of pathogenic strains of MDV using commercial chickens. When highly susceptible chickens were used, which are free of maternal antibodies against Marek's disease, the vaccine protected against challenge but the vaccine caused lymphoid organ atrophy, which might be a sign of immunosuppresion. This led us to the results that Meq is not only involved in transformation of lymphocytes but also suppression of infection after early cytolytic infection. In order to delineate these two functions of the Meq gene, we inserted site directed mutations into the Meq gene of MDV. Mutations were inserted into Meq gene responsible for dimerization domain of the protein. In-vivo experiment showed that this is responsible for loss of oncogenic property of the virus. US patent was filed and is pending for Marek's disease vaccine, serial number 10/430,773 dated May 6, 2003.

Impacts
This research was the first to conclusively identify the gene responsible of transformation of lymphocytes in Marek's disease. Disruption of this gene led us to discover the a vaccine capable of protecting chickens against highly virulent strains of the Marek's disease virus. US patent was filed on May 6, 2003, serial number 10/430,773. Disruption of the dimerization domain of was identified to be responsible for transformation of lymphocytes in chickens.

Publications

• Cui, X., Lee, L., Reed, W., Kung, H-J., and Reddy, S.M. (2004). Marek's disease virus encoded vIL8 gene is involved in early cytolytic infection but dispensable for establishment of latency. Journal of Virology 78(9): 4753-4760.

Progress 01/01/04 to 12/31/04

Outputs
We have generated cosmid clones from SN5 and A6 cosmids in which the phosphorylation sites coded by the Meq gene have been mutated. I am currently in the process of recovering mutant viruses, which the Meq gene is defective in phosphorylation. During the following year we will test these mutant in chickens to study their role in pathogenesis.

Impacts
We have shown that Marek's disease virus encodes a gene involved in transformation of lymphocytes that was responsible for a cancer like disease in chicken. We were able to generate a mutant virus in which this gene was deleted. This mutant virus has to potential to be used as a vaccine to protect against pathogenic strains of Marek's disease virus. Because of its commercial potential so we have applied a patent with the US patent and trademark office.

Publications

• Lupiani, B., Lee, L., Cui, X., Gimeno, I, Anderson, A., Morgan, R.W., Silva, R.F., Witter, R.L., Kung, H-J., and Reddy, S.M. (2004). Marek's disease virus-encoded Meq gene is involved in transformation of lymphocytes but is dispensable for replication. Proceedings of National Academy of Sciences 101 (32): 11815-20