Hepatitis C Virus
Hepatitis C is a single-stranded positive-sense RNA virus belonging to the Flaviviridae family. According to the Centers for Disease Control and Prevention (CDC), 75% to 85% of the people that are infected with HCV will develop chronic disease. Approximately 3.2 million persons in the United States now have chronic HCV infection. People with chronic infection are at risk for liver damage, and approximately one to five percent of HCV-infected people will die due to such consequences of chronic infection as cirrhosis and liver cancer. Combination therapy with pegylated interferon and ribavirin is the current treatment of choice, and is effective for up to 50% of patients infected with genotype 1, the most common genotype found in the United States. Despite this, chronic HCV infection still accounts for an estimated 8,000 to 10,000 deaths each year in the United States. There is currently no vaccine for HCV and alternative treatments are still needed.
Izzo1 conducted a study of the anti-tumor activity of ADI-PEG 20 in the treatment of hepatocellular carcinoma. Some of the patients included in this study also had chronic infection with HCV. By the end of treatment, half of the patients with HCV-serotype 1b had their viral titers reduced by up to 99%. This study and a study2 demonstrating the suppression of human immunodeficiency virus by arginine deiminase point to the potential therapeutic benefit of treating viral diseases with arginine deprivation therapy.
1 F. Izzo, M. Montella, A.P. Orlando, G. Nasti, G. Beneduce, G. Castello, F. Cremona, C.M. Ensor, F.W. Holtzberg, J.S. Bomalaski, M.A. Clark, S.A Curley, R. Orlando, F. Scordino, and B.E. Korba. Pegylated arginine deiminase lowers hepatitis C viral titers and inhibits nitric oxide synthesis. Journal of Gastroenterology and Hepatology 22 (2007) 86-91.
2 M. Kubo, H. Nishitsuji, K. Kurihara, T. Hayashi, T, Masuda, and M. Kannagi. Suppression of human immunodeficiency virus type 1 replication by arginine deiminase of Mycoplasma arginini. Journal of General Virology 87 (2006) 1589-1593.
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