In this study, Inovio developed a synthetic DNA vaccine which is encoded for the HBcAg antigen and represents a consensus of the unique HBcAg DNA sequences of all major HBV genotypes (A through E). When delivered by electroporation, researchers first demonstrated that this vaccine elicited strong HBcAg-specific T cell and antibody responses in the periphery (outside of the liver) by ELISpot, ICS and cell proliferation assays. Researchers observed that the vaccination could also induce antigen-specific CD8 and CD4 T cells that produced both IFN-y and TNF-a in the liver, indicating a strong vaccine-induced T cell response was also present in the liver.
Furthermore, study researchers found the vaccine-specific T cells exhibited a killing function, and could migrate to and stay in the liver and cause clearance of target cells without any evidence of liver injury. Taken together, this is the first study to provide evidence that intramuscular immunization can induce killer T cells that can migrate to the liver and eliminate target cells.
About Hepatitis B and Liver Cancer
Although an effective preventive vaccine against HBV infection has existed for over three decades, HBV remains a major epidemic, especially among the people of Asian and African descent. One-third of the world's population has been infected with HBV, with 400 million people chronically infected with the virus and at risk of developing cirrhosis or liver cancer. Currently, the only therapies available for chronically infected individuals are interferon-a and nucleoside analog treatments, which function by controlling viral replication but unfortunately do not clear infection. Interferon can prevent viral replication in only 30% of patients and does so with undesirable side effects.Liver cancer is the third most common cancer and the most deadly, killing most patients within five years of diagnosis. About 600,000 new cases arise each year. One of the major causes and risk factors for liver cancer is infection by hepatitis B.