Hepatitis b has also been called type b hepatitis, serum hepatitis, homologous serum jaundice. Hepatitis b virus hbv is a doublestranded dna virus and a member of the hepadnaviridae family of viruses 1,2. Hepadnaviruses hepatitis b viruses cause transient and chronic infections of the liver. Hepatitis b virus is a major human pathogen which has been extensively studied, yet its structure is unknown. Easl 2017 clinical practice guidelines on the management. Structural and functional analyses of hepatitis b virus x protein bh3. This form of hepatitis may occur as a superinfectionin a hepatitis b carrier or as a coinfection in an individual with acute hepatitis b. Attachment the virus gains entry into the cell by binding to receptors on the surface of the cell and entering it by endocytosis mediated by either clathrin or caveolin1. Vaccination effectively prevents infection and chronic hepatitis b virus carriage. Hepatitis b virus hbv causes transient and chronic infec tions of the liver. Although an estimated 1 million persons in the united states are chronically infected with hepatitis b virus, the prevalence of hepatitis b has declined since the implementation of a national.
Until recently, it was generally accepted that the protein moiety of the hepatitis b virus hbv envelope env and of sub viral hepatitis b surface antigen particles hbsag consists of a single. Hepatitis b virus employs two very closely related proteins. Consequences of hepatitis b and delta virus infectionfigure 6615. The finding may aid in the development of a vaccine to prevent the liver disease. Attention has focused on areas of the outer envelope coded by the s gene which are involved in the induction of a protective neutralising antibody response, and mutations which directly. Its genome is a single stranded rna molecule of positivestrand polarity of 7478 bases. Here, the authors provide the structure of the hbx bh3like domain and bclxl. Hepatitis b virus structure, epidemiology, symptoms, pathogenesis, diagnosis, treatment and vaccines. Hepatitis b virus hbv infects more than 300 million people worldwide and is a common cause of liver disease and liver cancer. Hepatitis c virus structure national institutes of. Hepatitis b virus dna made fully double stranded by a virion dna polymerase reaction could be converted from circular to linear molecules by heating in 10 mm nacl at 77 degrees c or in 100 mm nacl. The capsid of the hepatitis b virus has a very unique structure. The structure of hepatitis b envelope and molecular.
Viruses which require a second virus helper virus for replication. Hepatitis c virus structure national institutes of health nih. The hepatitis b virus was considered by a previous iarc working group in 1993. Expression of the hepatitis b virus surface, core and e antigen genes by stable rat and mouse cell lines. Hepatitis b virus hbv morphology, clinical features. The structure of hepatitis b envelope and molecular variants. The contributions of hepatitis b virus and hepatitis c virus infections to cirrhosis and primary liver cancer worldwide. It helps your body digest food, store energy, and remove poisons. Accumulated evidence in recent years has shown that the variation of hepatitis b virus hbv genomes may have profound implications for our understanding of hepatitis b pathogenesis and prevention. Although an estimated 1 million persons in the united states are chronically infected with hepatitis b virus, the prevalence of hepatitis b has declined. The viral structure of hepatitis b is similar in many ways to other viruses. Hepatitis b virus hbv constitutes a major public health threat in many areas of the world.
Hepatitis b virus is one of the smallest human pathogens, encoded by a 3200bp genome with only four open reading frames. A longitudinal study is available spanning the molecular evolution of hepatitis b virus over 25 years. Structures of hepatitis b virus core and eantigen immune. It can cause chronic infection and puts people at high risk of death from cirrhosis and liver cancer. Hepatitis c is an infectious disease caused by a virus. The overall structure of hepatitis b virus hbv is briefly described, followed by a discussion of its infectious lifecycle. Hepatitis b virus dna made fully double stranded by a virion dna polymerase reaction could be converted from circular to linear molecules by heating. In chronically infected patients, an elevated serum hepatitis b virus dna concentration is the main risk factor for disease progression, although there are other clinical and viral parameters that influence disease outcomes. Up to 90% of infants infected with the hepatitis b virus will develop a chronic infection. Hepatitis b virus hbv infection is a major public health problem, infecting approximately 300 million people worldwide, and is a major cause of chronic liver disease and hepatocellular carcinoma hcc. Transient infections run a course of several months, and chronic infections are often lifelong. This figure was used as a prior value for the fixed mean rate of amino acid replacement in protein x of the.
Structure of the hepatitis b virus the hepatitis b virus contains an outer envelope and an inner core. This sequence codes for a polyprotein which is processed to give rise to viral proteins vp1, vp2, vp3 and others. Deltavirus d requires the presence ofhepatitis b virus hbv infection. The hepatitis b virus is a small dna virus that belongs to the hepadnaviridae family. Viroids are the smallest known autonomously replicating molecules. Hepatitis b is a serious liver infection caused by the hepatitis b virus hbv. It then serves as a transcription template for all viral transcripts that are translated into the different viral proteins.
In response to the infection, the bodys immune system targets the liver, causing inflammation hepatitis. Hepatitis b virus structure, symptoms, diagnosis, treatment. Until recently, it was generally accepted that the protein moiety of the hepatitis b virus hbv envelope env and of sub viral hepatitis b surface antigen particles hbsag consists of a. Hepatitis d, or delta hepatitis, is another distinct virus that is dependent upon hepatitis b infection. Researchers determined the structure of a protein on the surface of the hepatitis c virus that allows it to gain entry into cells. What is the pathophysiology of hepatitis b virus hbv. Hepatitis b is a small enveloped dna virus that poses a major hazard to human health.
Statistics estimated 6,700 new infections in 2017 estimated 22,200 new infections in 2017 estimated 862,000 people living with chronic hbv infection in 2016 estimated 44,700 new infections in 2017 estimated 2. Hepatitis b virus hbv x protein, hbx, interacts with antiapoptotic bcl2 and bclxl proteins through its bh3like motif to promote hbv. Hbv infection can lead to chronic hep atitis b chb. Nov 24, 2018 vaccination effectively prevents infection and chronic hepatitis b virus carriage. Hepatitis a virus hav, hepatitis b virus hbv and hepatitis c virus hcv infect liver cellscalled hepatocytesthat provide the best conditions for these viruses to reproduce. Hepatitis b virus biology microbiology and molecular. The incubation period of hbv infection is 40150 days average, approximately 12 weeks. Hepatitis b is caused by the hepatitis b virus hbv, an enveloped virus containing a partially double stranded, circular dna genome, and classified within the family hepadnavirus. The hepatitis c virus hcv attacks the liver, leading to inflammation. In response to the infection, the bodys immune system. Although hepatitis delta virus genome may replicate independently once inside a host cell, it requires the help of hepatitis b virus to provide a protein coat so that it can be transmitted to new cells. In the core of the virus is the genetic material, dna, and the enzyme dna polymerase, which are. In acute infection, some may develop a rapid onset of sickness with vomiting, yellowish skin, tiredness, dark urine and abdominal pain.
Hepatitis b virus the hepatitis b virus was considered by a previous iarc working group in 1993 iarc, 1994. Hbv causes type b hepatitis, the most widespread and the most important type of viral hepatitis. Ciclopirox inhibits hepatitis b virus secretion by blocking. Hepatitis b virus an overview sciencedirect topics. This virus structure is a conventional icosahedral or helical structure that is surrounded by a lipid bilayer membrane, meaning the virus is encased or enveloped.
The replication strategy of these viruses has been described in great detail, but virushost. Hepatitis b virus, a major worldwide infectious and cancer promoting agent contains a dna genome of 3226 base pairs. It requires the presence of hepatitis b virus to complete its replication cycle. Hepatitis b virus x protein hbx binds antiapoptotic bclxl through its bh3like motif to promote viral replication. In 1970 australia antigen was identified as a structural component of the hepatitis b virus hbv.
One type, hepatitis b, is caused by the hepatitis b virus hbv. Pdf hepatitis b virus virology and replication researchgate. Hbv replicates through an rna intermediate and can integrate into the host genome. Hepatitis b virus is one of the smallest human pathogens, encoded by a 3,200bp genome with only four open reading frames. Hepatitis b virus dna and hepatocellular carcinoma. Chronic infections can lead to liver failure with cirrhosis and hepatocellular carcinoma. Hepatitis b is an infectious disease caused by the hepatitis b virus hbv that affects the liver. Statistics estimated 6,700 new infections in 2017 estimated 22,200 new infections in 2017 estimated 862,000 people living with chronic hbv infection in 2016. Many people have no symptoms during the initial infection. Hepatitis b is a potentially lifethreatening liver infection caused by the hepatitis b virus hbv. In part, this is the parsimony of viruses, where a minimal number of proteins perform a wide variety of functions. Related viruses in this family are also found in woodchucks, ground squirrels, tree squirrels, peking ducks, and herons.
Core and e antigen synthesis in rodent cells transformed with hepatitis b virus dna is associated with greater than genome length viral messenger rnas. An infected woman can give hepatitis b to her baby at birth. Hepatitis delta virus is the major human pathogen example. The infectious hbv virion dane particle has a spherical, doubleshelled structure 42 nm in diameter, consisting of a lipid envelope containing hbsag that. Cryoelectron microscopy of the viral cores expressed in escherichia coli or isolated from infected liver provides a means for determining the structure of. Having chronic hepatitis b increases your risk of developing liver failure, liver cancer or cirrhosis a condition that permanently scars of the liver. Hepatitis viruses most often found in the united states include a, b, c, and d. Study of the early steps of the hepatitis b virus life cycle. Abstract hepatitis b virus hbv is a human pathogen, causing the serious liver. The majority of adults infected have a transient hepatitis from which they completely recover and clear the virus. Evolutionary conservation in the hepatitis b virus core. The structure of hepatitis b envelope and molecular variants of hepatitis b virus.
As with acute hav infection, the clinical illness associated with acute hbv infection may range from mild. The likelihood that a person develops a chronic infection depends on the age at which someone becomes infected. Yet the virus shows a remarkable diversity in structural features, often with the same proteins adopting several conformations. Dane particle 42 nm, spherical 20 nm and filamentous 22 nm particles are three different viral.
Pdf hepatitis b virus hbv is an enveloped virus with an internal icosahedral. Hepatitis b virus biology microbiology and molecular biology. This starts with entry into the cell, transport of the partiallydouble stranded viral dna to the nucleus, its uncoating and repair by cellular polymerases to produce the covalentlyclosed circular dna. Hbv, a member of the hepadnaviridae family, is a small dna virus with unusual features similar to retroviruses. The crystal structure of the human hepatitis b virus capsid. Jul 19, 2019 hepatitis b virus x protein hbx binds antiapoptotic bclxl through its bh3like motif to promote viral replication. Yet the virus shows a remarkable diversity in structural features, often w. Hepatitis b is one of a few known nonretroviral viruses which use reverse transcription as a part of its replication process. Hepatitis b is a viral infection that attacks the liver and can cause both acute and chronic disease. Structural and functional analyses of hepatitis b virus x. Hepatitis b virus, a major worldwide infectious and cancer promoting agent contains a dna genome of 3226 base pairs that replicates by a reverse. For some people, hepatitis b infection becomes chronic, meaning it lasts more than six months. Aug 15, 2019 hepatitis b virus structure, epidemiology, symptoms, pathogenesis, diagnosis, treatment and vaccines. Since that time, new data have become available, these have been incorporated in the monograph, and taken into consideration in the present evaluation.
The replication strategy of these viruses has been described in great detail, but virus host interactions leading to. Hepatitis b spreads by contact with an infected persons blood, semen, or other body fluid. What is the pathophysiology of hepatitis b virus hbv infection. May 16, 2019 hepatitis b virus hbv is a doublestranded dna virus and a member of the hepadnaviridae family of viruses 1,2. Structural relationships between minor and major proteins of. It is composed of many monomers which interact to provide flexibility to its structure and function. It can cause scarring of the organ, liver failure, and cancer. Chronic hbv infection is a major global cause of hepatocellular carcinoma hcc. The envelope of the virus is formed when the virus is exiting the cell via budding, and the infectivity of these viruses is mostly dependent on the envelope. Accumulated evidence in recent years has shown that the variation of hepatitis b virus hbv genomes may have profound implications for our understanding of. Hepatitis b virus belongs to the hepadnavirus family of double stranded dna viruses see below hepatitis c virus is a flavivirus, a single stand rna virus hepatitis d which is also known as delta agent is a circular rna that is more similar to a plant viroid than a complete virus. Ciclopirox inhibits hepatitis b virus secretion by.