Two new drugs for Hepatitis C

Recently, two new oral drugs were considered for approval for Hepatitis C – a viral infection caused by Hepatitis C Virus (HCV) that affects liver cells and ultimately causes liver failure and/ or hepatocellular carcinoma due to chronic condition. One may not have heard much about the Hep C disease, but it is more common than HIV. WHO has estimated that around 150 million people around the world are chronically infected with HCV and more than 350,000 people die every year from Hep C related liver diseases. So far, smallpox is the only viral disease of humans that has been completely eradicated from the planet due to the success of vaccination strategies using live attenuated vaccinia viruses. No vaccine is available against HCV owing to the high mutation rates of it’s positive single stranded RNA genome.

Current treatment for Hep C involves injecting interferon- a class of cytokines which induces an antiviral state in the infected cells and enhances the immune system. It is given in combination with ribavirin, which is a nucleoside analog. Being a prodrug, ribavirin is activated inside the cell and inhibits viral replication by interfering with viral RNA synthesis and viral mRNA capping. However, simeprevir and sofosbuvir – the newly approved oral medications, are meant to directly interfere with HCV’s ability to replicate and make proteins when taken along with ribavirin. In a phase II trial, about 78% of patients infected with HCV were cured with a combination of sofosbuvir and ribavirin without the need of interferon. This is not a new strategy when it comes to antiviral drug treatments. Similar kinds of “drug cocktails” are used to treat HIV infection as a part of Highly Active Antiretroviral Treatment therapy.

In an interview with Nature, pharmacologist Raymond Schinazi of Emory University said “This is the first time in the history of humankind that we have a cure for a viral disease”. This statement may seem too far fetched considering the nature of the virus and it’s ability to reside in the cells for many years causing no external symptoms. Also, there is always the case of emergence of drug resistant strains due to highly mutable viral genomes. Antiviral drug treatment studies take extremely long periods of time to evaluate the outcome across the globe. However, an advantage for HCV treatment efforts is that the virus has no animal reservoirs and is transmitted between people only through contaminated blood. Increased and improved blood screening techniques can prevent transmission of the virus among populations.

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