Hepatitis B virus,HBx mutants and their role in hepatocellular carcinoma

Hepatocellular carcinoma(HCC)is one of the leading causes of death induced by cancer in the modern world and majority of the cases are related to chronic hepatitis B virus(HBV)infection.HBV-encoded X protein(HBx)is known to play a pivotal role in the pathogenesis of viral induced HCC.HBx is a multifunctional protein of17 kDa which modulates several cellular processes by direct or indirect interaction with a repertoire of host factors resulting in HCC.HBX might interfere with several cellular processes such as oxidative stress,DNA repair,signal transduction,transcription,protein degradation,cell cycle progression and apoptosis.A number of reports have indicated that HBx is one of the most common viral ORFs that is often integrated into the host genome and its sequence variants play a crucial role in HCC.By mutational or deletion analysis it was shown that carboxy terminal of HBx has a likely role in protein-protein interactions,transcriptional transactivation,DNA repair,cell,signaling and pathogenesis of HCC.The accumulated evidence thus far suggests that it is difficult to understand the mechanistic nature of HBx associated HCC,and HBx mediated transcriptional transactivation and signaling pathways may be a major determinant.This article addresses the role of HBx in the development of HCC with particular emphasis on HBx mutants and their putative targets.

Potential mechanisms of hepatitis B virus induced liver injury

Chronic active hepatitis(CAH) is acknowledged as an imperative risk factor for the development of liver injury and hepatocellular carcinoma.The histological end points of CAH are chronic inflammation,fibrosis and cirrhosis which are coupled with increased DNA synthesis in cirrhotic vs healthy normal livers.The potential mechanism involved in CAH includes a combination of processes leading to liver cell necrosis,inflammation and cytokine production and liver scaring(fibrosis).The severity of liver damage is regulated by Hepatitis B virus genotypes and viral components.The viral and cellular factors that contribute to liver injury are discussed in this article.Liver injury caused by the viral infection affects many cellular processes such as cell signaling,apoptosis,transcription,DNA repair which in turn induce radical effects on cell survival,growth,transformation and maintenance.The consequence of such perturbations is resulted in the alteration of bile secretion,gluconeogenesis,glycolysis,detoxification and metabolism of carbohydrates,proteins,fat and balance of nutrients.The identification and elucidation of the molecular pathways perturbed by the viral proteins are important in order to design effective strategy to minimize and/or restore the hepatocytes injury.

Hepatitis C virus and neurological damage

Chronic hepatitis C virus(HCV) infection exhibits a wide range of extrahepatic complications, affecting various organs in the human body. Numerous HCV patients suffer neurological manifestations, ranging from cognitive impairment to peripheral neuropathy. Overexpression of the host immune response leads to the production of immune complexes, cryoglobulins, as well as autoantibodies, which is a major pathogenic mechanism responsible for nervous system dysfunction. Alternatively circulating inflammatory cytokines and chemokines and HCV replication in neurons is another factor that severely affects the nervous system. Furthermore, HCV infection causes both sensory and motor peripheral neuropathy in the mixed cryoglobulinemia as well as known as an important risk aspect for stroke. These extrahepatic manifestations are the reason behind underlying hepatic encephalopathy and chronic liver disease. The brain is an apt location for HCV replication, where the HCV virus may directly wield neurotoxicity. Other mechanisms that takes place by chronic HCV infection due the pathogenesis of neuropsychiatric disorders includes derangement of metabolic pathways of infected cells, autoimmune disorders, systemic or cerebral inflammation and alterations in neurotransmitter circuits. HCV and its pathogenic role is suggested by enhancement of psychiatric and neurological symptoms in patients attaining a sustained virologic response followed by treatment with interferon; however, further studies are required to fully assess the impact of HCV infection and its specific antiviral targets associated with neuropsychiatric disorders.