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"HBV" redirects here. For other uses, see HBV (disambiguation).
Hepatitis B virus
Micrograph showing hepatitis B virions
Micrograph showing hepatitis B virions
Virus classification
Group: Group VII (dsDNA-RT)
Family: Hepadnaviridae
Genus: Orthohepadnavirus
Species: Hepatitis B virus

Hepatitis B virus infects the liver of hominoidae, including humans, and causes an inflammation called hepatitis. Virus classification involves naming and placing Viruses into a taxonomic system A reverse transcribing virus is any virus which replicates using Reverse transcription, the formation of DNA from an RNA template Hepadnaviruses are a family of Viruses which can cause Liver infections in humans and animals The liver is a vital organ in the human body and is present in Vertebrates and some other animals Inflammation ( Latin, inflamatio, to set on fire is the complex biological response of vascular tissues to harmful stimuli such as Pathogens Hepatitis (plural hepatitides) implies injury to the Liver characterized by the presence of Inflammatory cells in the tissue of It is a DNA virus and one of many unrelated viruses that cause viral hepatitis. A virus (from the Latin virus meaning Toxin or Poison) is a sub-microscopic infectious agent that is unable Hepatitis (plural hepatitides) implies injury to the Liver characterized by the presence of Inflammatory cells in the tissue of The disease was originally known as "serum hepatitis"[1]and has caused epidemics in parts of Asia and Africa. In Epidemiology, an epidemic (from Greek epi- upon + demos people is a classification of a disease that appears as new cases in a Hepatitis B is endemic in China and various other parts of Asia. In Epidemiology, an Infection is said to be endemic (from Greek en- in or within + demos people in a Population when Hepatitis B is recognized as endemic in China by the World Health Organization (WHO [2] The proportion of the world's population currently infected with the virus is estimated at 3 to 6%, but up to a third have been exposed. Symptoms of the acute illness caused by the virus include liver inflammation, vomiting, jaundice, and rarely, death. Jaundice, also known as icterus (attributive adjective "icteric" is yellowish discoloration of the Skin, sclerae (whites of the eyes Chronic hepatitis B may eventually cause liver cirrhosis and liver cancer, a fatal disease with very poor response to current chemotherapy. Cirrhosis is a consequence of chronic Liver Disease characterized by replacement of liver tissue by fibrous Scar tissue as well as regenerative Hepatocellular carcinoma (HCC also called hepatoma) is a primary malignancy (cancer of the Liver. [3] The infection is preventable by vaccination. Vaccination is the administration of Antigenic material (the Vaccine) to produce immunity to a disease [4]

Contents

Symptoms and complications

Hepatitis B virus infection may either be acute (self-limiting) or chronic (long-standing). Persons with self-limiting infection clear the infection spontaneously within weeks to months.

Children are less likely than adults to clear the infection. More than 95% of people who become infected as adults or older children will stage a full recovery and develop protective immunity to the virus. However, only 5% of newborns that acquire the infection from their mother at birth will clear the infection. Of those infected between the age of one to six, 70% will clear the infection. [5]

Acute infection with hepatitis B virus is associated with acute viral hepatitis - an illness that begins with general ill-health, loss of appetite, nausea, vomiting, body aches, mild fever, dark urine, and then progresses to development of jaundice. Hepatitis (plural hepatitides) implies injury to the Liver characterized by the presence of Inflammatory cells in the tissue of Jaundice, also known as icterus (attributive adjective "icteric" is yellowish discoloration of the Skin, sclerae (whites of the eyes It has been noted that itchy skin has been an indication as a possible symptom of all hepatitis virus types. The illness lasts for a few weeks and then gradually improves in most affected people. A few patients may have more severe liver disease (fulminant hepatic failure), and may die as a result of it. Acute liver failure is the appearance of severe complications rapidly after the first signs of liver disease (such as Jaundice) and indicates that the liver has sustained severe The infection may be entirely asymptomatic and may go unrecognized.

Chronic infection with Hepatitis B virus may be either asymptomatic or may be associated with a chronic inflammation of the liver (chronic hepatitis), leading to cirrhosis over a period of several years. Cirrhosis is a consequence of chronic Liver Disease characterized by replacement of liver tissue by fibrous Scar tissue as well as regenerative This type of infection dramatically increases the incidence of hepatocellular carcinoma (liver cancer). Hepatocellular carcinoma (HCC also called hepatoma) is a primary malignancy (cancer of the Liver. Chronic carriers are encouraged to avoid consuming alcohol as it increases their risk for cirrhosis and liver cancer. Cirrhosis is a consequence of chronic Liver Disease characterized by replacement of liver tissue by fibrous Scar tissue as well as regenerative Hepatitis B virus has been linked to the development of Membranous glomerulonephritis (MGN). Membranous glomerulonephritis ( MGN) also known as membranous nephropathy, is a slowly progressive disease of the Kidney affecting mostly patients between [6]

Hepatitis D infection can only occur with a concomitant infection with Hepatitis B virus because the Hepatitis D virus uses the Hepatitis B virus surface antigen to form a capsid. Hepatitis D is a Disease caused by a small circular RNA virus ( Hepatitis delta virus or hepatitis D virus, HDV) [7] Co-infection with hepatitis D increases the risk of liver cirrhosis and liver cancer. [8] Polyarteritis nodosa is more common in people with hepatitis B infection. Polyarteritis nodosa (or periarteritis nodosa) is a Vasculitis of medium-sized Arteries, which become swollen and damaged from attack by rogue Immune

Diagnosis

Hepatitis B viral antigens and antibodies detectable in the blood following acute infection.
Hepatitis B viral antigens and antibodies detectable in the blood following acute infection.
Hepatitis B viral antigens and antibodies detectable in the blood of a chronically infected person
Hepatitis B viral antigens and antibodies detectable in the blood of a chronically infected person

The tests, called assays, for detection of hepatitis B virus infection involve serum or blood tests that detect either viral antigens (proteins produced by the virus) or antibodies produced by the host. An assay is a procedure where a property or concentration of an Analyte is measured Blood plasma is the Liquid component of Blood, in which the Blood cells are suspended A blood test is a laboratory analysis performed on a Blood sample that is usually extracted from a Vein in the arm using a needle, or via Antibodies (also known as immunoglobulins, abbreviated Ig) are Gamma globulin Proteins that are found in Blood or other Bodily Interpretation of these assays is complex. [9]

The hepatitis B surface antigen (HBsAg) is most frequently used to screen for the presence of this infection. It is the first detectable viral antigen to appear during infection. However, early in an infection, this antigen may not be present and it may be undetectable later in the infection as it is being cleared by the host. The infectious virion contains an inner "core particle" enclosing viral genome. The icosahedral core particle is made of 180 or 240 copies of core protein, alternatively known as hepatitis B core antigen, or HBcAg. During this 'window' in which the host remains infected but is successfully clearing the virus, IgM antibodies to the hepatitis B core antigen (anti-HBc IgM) may be the only serological evidence of disease. Immunoglobulin M, or IgM for short is a basic Antibody that is present on B cells It is the primary antibody against A and B

Shortly after the appearance of the HBsAg, another antigen named as the hepatitis B e antigen (HBeAg) will appear. Traditionally, the presence of HBeAg in a host's serum is associated with much higher rates of viral replication and enhanced infectivity; however, variants of the hepatitis B virus do not produce the 'e' antigen, so this rule does not always hold true. During the natural course of an infection, the HBeAg may be cleared, and antibodies to the 'e' antigen (anti-HBe) will arise immediately afterwards. This conversion is usually associated with a dramatic decline in viral replication.

If the host is able to clear the infection, eventually the HBsAg will become undetectable and will be followed by IgG antibodies to the hepatitis B surface antigen and core antigen, (anti-HBs and anti HBc IgG). Immunoglobulin G ( IgG) is a Monomeric Immunoglobulin, built of two heavy chains γ and two light chains. [10] A person negative for HBsAg but positive for anti-HBs has either cleared an infection or has been vaccinated previously.

Individuals who remain HBsAg positive for at least six months are considered to be hepatitis B carriers. [11] Carriers of the virus may have chronic hepatitis B, which would be reflected by elevated serum alanine aminotransferase levels and inflammation of the liver, as revealed by biopsy. Alanine transaminase or ALT is a Transaminase Enzyme ( It is also called serum glutamic pyruvic transaminase (SGPT or alanine aminotransferase Carriers who have seroconverted to HBeAg negative status, particularly those who acquired the infection as adults, have very little viral multiplication and hence may be at little risk of long-term complications or of transmitting infection to others. [12]

More recently, PCR tests have been developed to detect and measure the amount of viral nucleic acid in clinical specimens. These tests are called viral loads and are used to assess a person's infection status and to monitor treatment. Viral load is a measure of the severity of a viral infection and can be calculated by estimating the amount of virus in an involved body fluid [13]

Transmission

Prevalence of Hepatitis B virus as of 2005.
Prevalence of Hepatitis B virus as of 2005.

Transmission results from exposure to infectious blood or body fluids containing blood. Possible forms of transmission include (but are not limited to) unprotected sexual contact, blood transfusions, re-use of contaminated needles & syringes, and vertical transmission from mother to child during childbirth. Blood transfusion is the process of transferring Blood or blood-based products from one person into the Circulatory system of another Needle sharing is the colloquialism for the reuse of Syringes by multiple Illegal drug users to administer Intravenous drugs and is a primary vector for Vertical transmission, also known as Mother-to-child transmission refers to transmission of an Infection, such as HIV, Hepatitis B, or Hepatitis Without intervention, a mother who is positive for the hepatitis B surface antigen confers a 20% risk of passing the infection to her offspring at the time of birth. This risk is as high as 90% if the mother is also positive for the hepatitis B e antigen. HBV can be transmitted between family members within households, possibly by contact of nonintact skin or mucous membrane with secretions or saliva containing HBV. [14] However, at least 30% of reported hepatitis B among adults cannot be associated with an identifiable risk factor. [15]

The primary method of transmission reflects the prevalence of chronic HBV infection in a given area. In low prevalence areas such as the continental United States and Western Europe, where less than 2% of the population is chronically infected, injection drug abuse and unprotected sex are the primary methods, although other factors may be important. The United States of America —commonly referred to as the [16] In moderate prevalence areas, which include Eastern Europe, Russia, and Japan, where 2-7% of the population is chronically infected, the disease is predominantly spread among children. Russia (Россия Rossiya) or the Russian Federation ( Rossiyskaya Federatsiya) is a transcontinental Country extending For a topic outline on this subject see List of basic Japan topics. In high prevalence areas such as China and South East Asia, transmission during childbirth is most common, although in other areas of high endemicity such as Africa, transmission during childhood is a significant factor. China ( Wade-Giles ( Mandarin) Chung¹kuo² is a cultural region, an ancient Civilization, and depending on perspective a National [17] The prevalence of chronic HBV infection in areas of high endemicity is at least 8%.

Pathogenesis

Cirrhosis of the liver and liver cancer may ensue from Hepatitis B.
Cirrhosis of the liver and liver cancer may ensue from Hepatitis B. Cirrhosis is a consequence of chronic Liver Disease characterized by replacement of liver tissue by fibrous Scar tissue as well as regenerative Hepatocellular carcinoma (HCC also called hepatoma) is a primary malignancy (cancer of the Liver.

The hepatitis B virus primarily interferes with the functions of the liver by replicating in liver cells, known as hepatocytes. Hepatocytes make up 70-80% of the Cytoplasmic mass of the Liver. During HBV infection, the host immune response causes both hepatocellular damage and viral clearance. An immune system is a collection of mechanisms within an Organism that protects against Disease by identifying and killing Pathogens and Tumor Although the innate immune response does not play a significant role in these processes, the adaptive immune response, particularly virus-specific cytotoxic T lymphocytes (CTLs), contributes to most of the liver injury associated with HBV infection. A cytotoxic T cell (also known as TC, CTL T-Killer cell cytolytic T cell CD8+ T-cells or killer T cell) belongs to a sub-group of T lymphocytes By killing infected cells and by producing antiviral cytokines capable of purging HBV from viable hepatocytes, CTLs eliminate the virus. Cytokines are a category of signalling Proteins and Glycoproteins that like Hormones and Neurotransmitters, are used extensively in cellular [18] Although liver damage is initiated and mediated by the CTLs, antigen-nonspecific inflammatory cells can worsen CTL-induced immunopathology, and platelets activated at the site of infection may facilitate the accumulation of CTLs into the liver. Platelets, or Thrombocytes, are small cytoplasmic bodies derived from cells They circulate in the Blood of Mammals and are involved [19]

Reactivation

Hepatitis B virus DNA persists in the body after infection and in some people the disease re-occurs. [20] Although rare, reactivation is seen most often in people with impaired immunity. [21]

Treatment

Acute hepatitis B infection does not usually require treatment because most adults clear the infection spontaneously. [22] Early antiviral treatment may only be required in fewer than 1% of patients, whose infection takes a very aggressive course ("fulminant hepatitis") or who are immunocompromised. In Medicine, immunodeficiency (or immune deficiency) is a state in which the Immune system 's ability to fight Infectious disease is compromised On the other hand, treatment of chronic infection may be necessary to reduce the risk of cirrhosis and liver cancer. Chronically infected individuals with persistently elevated serum alanine aminotransferase, a marker of liver damage, and HBV DNA levels are candidates for therapy. Alanine transaminase or ALT is a Transaminase Enzyme ( It is also called serum glutamic pyruvic transaminase (SGPT or alanine aminotransferase [23]

Although none of the available drugs can clear the infection, they can stop the virus from replicating, and prevent liver damage such as cirrhosis and liver cancer. Treatments include antiviral drugs such as lamivudine, adefovir and entecavir, and immune system modulators such as interferon alpha. Antiviral drugs are a class of Medication used specifically for treating viral Infections Like Antibiotics for Bacteria, specific antivirals Lamivudine (2'3'-dideoxy-3'-thia Cytidine, commonly Adefovir dipivoxil, previously called bis-POM PMEA, with trade names Preveon and Hepsera, is an orally-administered nucleotide analog Reverse Entecavir ( INN) (ɛnˈtɛkəvɪr is an oral Antiviral drug used in the treatment of Hepatitis B infection An immune system is a collection of mechanisms within an Organism that protects against Disease by identifying and killing Pathogens and Tumor Interferons ( IFN s are natural Proteins produced by the cells of the Immune system of most Vertebrates in response to challenges by foreign agents However, some individuals are much more likely to respond than others and this might be because of the genotype of the infecting virus or the patient's heredity. The genotype is the genetic constitution of a cell an organism or an individual (i The treatment works by reducing the viral load, (the amount of virus particles as measured in the blood), which in turn reduces viral replication in the liver. Viral load is a measure of the severity of a viral infection and can be calculated by estimating the amount of virus in an involved body fluid

On March 29, 2005, the US Food and Drug Administration (FDA) approved Entecavir for the treatment of Hepatitis B. Entecavir ( INN) (ɛnˈtɛkəvɪr is an oral Antiviral drug used in the treatment of Hepatitis B infection [24] On February 25, 2005, the EU Commission approved Peginterferon alfa-2a (Pegasys). The European Commission (formally the Commission of the European Communities) is the executive branch of the European Union. Pegylated interferon alfa-2a (40kD (commercial name PEGASYS) is an Antiviral drug discovered at the pharmaceutical company F [25][26] On October 27, 2006, telbivudine gained FDA approval. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Telbivudine is an Antiviral drug used in the treatment of Hepatitis B infection It is marketed under the brand name Tyzeka in the US and Sebivo outside the US. It is approved in Switzerland. Switzerland (English pronunciation; Schweiz Swiss German: Schwyz or Schwiiz Suisse Svizzera Svizra officially the Swiss Confederation [27]

Infants born to mothers known to carry hepatitis B can be treated with antibodies to the hepatitis B virus (hepatitis B immune globulin or HBIg). When given with the vaccine within twelve hours of birth, the risk of acquiring hepatitis B is reduced 95%. This treatment allows a mother to safely breastfeed her child.

Vaccination

Main article: Hepatitis B vaccine
HBsAg
HBsAg

Several vaccines have been developed for the prevention of hepatitis B virus infection. Hepatitis B vaccine is a Vaccine developed for the prevention of hepatitis B virus infection. A vaccine is a biological preparation which is used to establish or improve immunity to a particular disease These rely on the use of one of the viral envelope proteins (hepatitis B surface antigen or HBsAg). The vaccine was originally prepared from plasma obtained from patients who had long-standing hepatitis B virus infection. However, currently, these are more often made using recombinant DNA technology, though plasma-derived vaccines continue to be used; the two types of vaccines are equally effective and safe. Recombinant DNA is a form of synthetic DNA that is engineered through the combination or insertion of one or more DNA strands thereby combining DNA sequences [28]

Following vaccination Hepatitis B Surface antigen may be detected in serum for several days; this is known as vaccine antigenaemia. [29]

Microbiology

Structure

A simplified drawing of the HBV particle and surface antigen
A simplified drawing of the HBV particle and surface antigen

Hepatitis B virus (HBV) is a member of the Hepadnavirus family. Hepadnaviruses are a family of Viruses which can cause Liver infections in humans and animals [10] The virus particle, (virion) consists of an outer lipid envelope and an icosahedral nucleocapsid core composed of protein. A virus (from the Latin virus meaning Toxin or Poison) is a sub-microscopic infectious agent that is unable Lipids are broadly defined as any fat- Soluble ( lipophilic) naturally-occurring Molecule, such as fats oils waxes cholesterol sterols fat-soluble In Geometry, an icosahedron ( Greek: eikosaedron, from eikosi twenty + hedron seat /ˌaɪ A Nucleocapsid is the Genome (DNA or RNA of a virus and the protein coat surrounding it (the Capsid) Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl The nucleocapsid encloses the viral DNA and a DNA polymerase that has reverse transcriptase activity. In Biochemistry, a reverse transcriptase, also known as RNA-dependent DNA polymerase, is a DNA polymerase Enzyme that transcribes [30] The outer envelope contains embedded proteins which are involved in viral binding of, and entry into, susceptible cells. The virus is one of the smallest enveloped animal viruses with a virion diameter of 42nm, but pleomorphic forms exist, including filamentous and spherical bodies lacking a core. Pleomorphism is the occurrence of two or more structural forms during a life cycle, especially of certain plants These particles are not infectious and are composed of the lipid and protein that forms part of the surface of the virion, which is called the surface antigen (HBsAg), and is produced in excess during the life cycle of the virus. HBsAg is the surface Antigen of the Hepatitis -B-Virus ( HBV) [31]

Genome

"HBc" redirects here. For other uses, see HBC.
The genome organisation of HBV. The genes overlap
The genome organisation of HBV. The genes overlap

The genome of HBV is made of circular DNA, but it is unusual because the DNA is not fully double-stranded. In classical genetics the genome of a Diploid Organism including Eukarya refers to a full set of chromosomes or genes in a Gamete, thereby Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known One end of the full length strand is linked to the viral DNA polymerase. A DNA Polymerase is an Enzyme that assists in DNA replication. The genome is 3020-3320 nucleotides long (for the full length strand) and 1700-2800 nucleotides long (for the short length strand). [32] The negative-sense, (non-coding), is complementary to the viral mRNA. The viral DNA is found in the nucleus soon after infection of the cell. The partially double-stranded DNA is rendered fully double-stranded by completion of the (+) sense strand and removal of a protein molecule from the (-) sense strand and a short sequence of RNA from the (+) sense strand. Non-coding bases are removed from the ends of the (-)sense strand and the ends are rejoined. There are four known genes encoded by the genome called C, X, P, and S. The core protein is coded for by gene C (HBcAg), and its start codon is preceded by an upstream in-frame AUG start codon from which the pre-core protein is produced. HBeAg is produced by proteolytic processing of the pre-core protein. The DNA polymerase is encoded by gene P. Gene S is the gene that codes for the surface antigen (HBsAg). The HBsAg gene is one long open reading frame but contains three in frame "start" (ATG) codons that divide the gene into three sections, pre-S1, pre-S2, and S. Because of the multiple start codons, polypeptides of three different sizes called large, middle, and small (pre-S1 + pre-S2 + S, pre-S2 + S, or S) are produced. [33] The function of the protein coded for by gene X is not fully understood. [34]

Replication

Hepatitis B virus replication .
Hepatitis B virus replication .

The life cycle of Hepatitis B virus is complex. Hepatitis B is one of a few known non-retroviral viruses which use reverse transcription as a part of its replication process. A retrovirus is any Virus belonging to the viral family Retroviridae. Reverse transcription is the process of making a double stranded DNA (deoxyribonucleic acid molecule from a single stranded RNA (ribonucleic acid template The virus gains entry into the cell by binding to a receptor on the surface of the cell and enters it by endocytosis. Endocytosis is a process where cells absorb material ( Molecules such as proteins from the outside by engulfing it with their Cell membrane. Because the virus multiplies via RNA made by a host enzyme, the viral genomic DNA has to be transferred to the cell nucleus by host proteins called chaperones. The partially double stranded viral DNA is then made fully double stranded and transformed into closed circular supercoiled DNA (cccDNA) that serves as a template for transcription of four viral mRNAs. Messenger ribonucleic acid ( mRNA) is a molecule of RNA encoding a chemical "blueprint" for a Protein product The largest mRNA, (which is longer than the viral genome), is used to make the new copies of the genome and to make the capsid core protein and the viral DNA polymerase. For the leaf bug see Miridae. A capsid is the protein shell of a virus. A DNA Polymerase is an Enzyme that assists in DNA replication. These four viral transcripts undergo additional processing and go on to form progeny virions which are released from the cell or returned to the nucleus and re-cycled to produce even more copies. [33][35] The long mRNA is then transported back to the cytoplasm where the virion P protein synthesizes DNA via its reverse transcriptase activity.

Serotypes

The virus is divided into four major serotypes (adr, adw, ayr, ayw) based on antigenic epitopes present on its envelope proteins, and into eight genotypes (A-H) according to overall nucleotide sequence variation of the genome. For the term's use in bacteriology see Serovar. Transplants between genetically non-identical humans induce the creation of antibodies in the recipient An epitope, also known as antigenic determinant, is the part of a Macromolecule that is recognized by the Immune system, specifically by antibodies The genotypes have a distinct geographical distribution and are used in tracing the evolution and transmission of the virus. Differences between genotypes affect the disease severity, course and likelihood of complications, and response to treatment and possibly vaccination. [36][37]

History

The earliest record of an epidemic caused by Hepatitis B virus was made by Lurman in 1885. [38] An outbreak of smallpox occurred in Bremen in 1883 and 1,289 shipyard employees were vaccinated with lymph from other people. Smallpox is an Infectious disease unique to humans caused by either of two virus variants named Variola major and Variola minor. Vaccination is the administration of Antigenic material (the Vaccine) to produce immunity to a disease The lymphatic system in Vertebrates is a network of conduits that carry a clear fluid called Lymph. After several weeks, and up to eight months later, 191 of the vaccinated workers became ill with jaundice and were diagnosed as suffering from serum hepatitis. Jaundice, also known as icterus (attributive adjective "icteric" is yellowish discoloration of the Skin, sclerae (whites of the eyes Other employees who had been inoculated with different batches of lymph remained healthy. Lurman's paper, now regarded as a classical example of an epidemiological study, proved that contaminated lymph was the source of the outbreak. Epidemiology is the study of factors affecting the Health and Illness of populations and serves as the foundation and Logic of interventions made in the Later, numerous similar outbreaks were reported following the introduction, in 1909, of hypodermic needles that were used, and more importantly reused, for administering Salvarsan for the treatment of syphilis. A hypodermic needle is a hollow needle commonly used with a Syringe to inject substances into the body Arsphenamine, also known as Salvarsan and 606, is a drug that was used to treat Syphilis and trypanosomiasis. Syphilis is a Sexually transmitted disease caused by the spirochetal Bacterium Treponema pallidum pallidum. The virus was not discovered until 1965 when Baruch Blumberg, then working at the National Institutes of Health (NIH), discovered the Australia antigen (later known to be Hepatitis B surface antigen, or HBsAg) in the blood of Australian aboriginal people. Baruch Samuel Blumberg (born July 28, 1925) is an American scientist and recipient of the 1976 "NIH" redirects here For other meanings of NIH see NIH (disambiguation. HBsAg is the surface Antigen of the Hepatitis -B-Virus ( HBV) [39] Although a virus had been suspected since the research published by MacCallum in 1947. [40] In 1970, D. S. Dane and others discovered the virus particle by electron microscopy. An electron microscope is a type of Microscope that uses Electrons to illuminate a specimen and create an enlarged image [41] By the early 1980s the genome of the virus had been sequenced,[42] and the first vaccines were being tested. In classical genetics the genome of a Diploid Organism including Eukarya refers to a full set of chromosomes or genes in a Gamete, thereby [43]

See also

References

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External links

Hepatitis B
Classification and external resources
ICD-10 B16.,
B18.0-B18.1
ICD-9 070.2-070.3
OMIM 610424
DiseasesDB 5765
MedlinePlus 000279
eMedicine med/992  ped/978
MeSH D006509
The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify Diseases The International Statistical Classification of Diseases and Related Health Problems 10th Revision ( ICD -10) is a coding of diseases and signs symptoms abnormal findings A00-A79 - Bacterial infections and other intestinal infectious diseases and STDs (A00-A09 Intestinal Infectious diseases ( A00-A79 - Bacterial infections and other intestinal infectious diseases and STDs (A00-A09 Intestinal Infectious diseases ( A00-A79 - Bacterial infections and other intestinal infectious diseases and STDs (A00-A09 Intestinal Infectious diseases ( The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify Diseases The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. The Mendelian Inheritance in Man project is a Database that catalogues all the known Diseases with a genetic component, and—when possible—links them The Diseases Database is a free Website that provides information about the relationships between medical conditions Symptoms, and Medications. MedlinePlus, with the MedlinePlus Medical Encyclopedia, is a website network containing Health information from the world's largest medical Library eMedicine is an online clinical medical knowledge base that was founded in 1996 by Scott Plantz and Richard Lavely two medical doctors Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books
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