Isolation of the novel agent from human stool samples that is associated with sporadic non-A, non-B hepatitis

Discovery of Hepatitis E and Its Impact on Global Health: A Journey of 44 Years about an Incredible Human-Interest Story

The story of the discovery of hepatitis E originated in the late 1970s with my extreme belief that there was a hidden saga in the relationship between jaundice and pregnancy in developing countries and the opportunity for a massive epidemic of viral hepatitis, which hit the Gulmarg Kashmir region in November 1978. Based on data collected from a door-to-door survey, the existence of a new disease, epidemic non-A, non-B hepatitis, caused by a hitherto unknown hepatitis virus, was announced. This news was received by the world community with hype and skepticism. In the early 1980s, the world watched in awe as an extreme example of human self-experimentation led to the identification of VLP. In 1990, a cDNA clone from the virus responsible for epidemic non-A, non-B hepatitis was isolated. Over the years, we traversed three eras of ambiguity, hope, and hype of hepatitis E research and conducted several seminal studies to understand the biology of HEV and manifestations of hepatitis E. Many milestones have been reached on the long and winding road of hepatitis E research to understand the structure, biology, and diversity of the agent, changing the behavior of the pathogen in developed countries, and the discovery of a highly effective vaccine.

A proposed disease classification system for duck viral hepatitis

The nomenclature of duck viral hepatitis (DVH) was historically not a problem. However, 14 hepatotropic viruses among 10 different genera are associated with the same disease name, DVH. Therefore, the disease name increasingly lacks clarity and may no longer fit the scientific description of the disease. Because one disease should not be attributed to 10 genera of viruses, this almost certainly causes misunderstanding regarding the disease-virus relationship. Herein, we revisited the problem and proposed an update to DVH disease classification. This classification is based on the nomenclature of human viral hepatitis and the key principle of Koch's postulates (“one microbe and one disease”). In total, 10 types of disease names have been proposed. These names were literately matched with hepatitis-related viruses. We envision that this intuitive nomenclature system will facilitate scientific communication and consistent interpretation in this field, especially in the Asian veterinary community, where these diseases are most commonly reported.

Famous endoscopy quotes

These quotations, whether humorous or serious, provide insight into how gastroenterology nurses, gastroenterologists, and endoscopists feel about themselves as professionals, how other healthcare professionals perceive them, and their image in popular culture. Recognition of these aspects of gastroenterology nursing, gastroenterology, and endoscopy are important for self-improvement, correcting public misperceptions, and appreciating how patient misperceptions about gastroenterology nurses and gastroenterologists and patient attitudes toward endoscopy may present barriers that gastroenterology professionals must overcome to improve patient care. These quotations also fulfill a need for witticisms during dry endoscopy lectures!

GB virus type C interactions with HIV: the role of envelope glycoproteins

GB virus C/hepatitis G virus (GBV-C/HGV) is the most closely related human virus to hepatitis C virus (HCV). GBV-C is lymphotropic and not associated with any known disease, although it is associated with improved survival in HIV-infected individuals. In peripheral blood mononuclear cells, GBV-C induces the release of soluble ligands for HIV entry receptors (RANTES, MIP-1a, MIP-1b and SDF-1), suggesting that GBV-C may interact with lymphocytes to induce a chemokine and/or cytokine milieu that is inhibitory to HIV infection. Expression of GBV-C envelope glycoprotein E2 in CD4+ T cells or addition of recombinant E2 to CD4 cells recapitulates the HIV inhibition seen with GBV-C infection. Like HCV E2, GBV-C E2 is predicted to be post-translationally processed in the endoplasmic reticulum and is involved with cell binding. The C-termini of GBV-C E1 and E2 proteins contain predicted transmembrane domains sharing features with HCV TM domains. To date, cellular receptor(s) for GBV-C E2 have not been identified. GBV-C E2-mediated HIV inhibition is dose-dependent and HIV replication is blocked at the binding and/or entry step. In addition, a putative GBV-C E2 fusion peptide interferes with HIV gp41 peptide oligomerization required for HIV-1 fusion, further suggesting that GBV-C E2 may inhibit HIV entry. Additional work is needed to identify the GBV-C E2 cellular receptor, characterize GBV-C E2 domains responsible for HIV inhibition, and to examine GBV-C E2-mediated fusion in the context of the entire envelope protein or viral-particles. Understanding the mechanisms of action may identify novel approaches to HIV therapy.

[The novel non-A, non-E hepatitis viruses and their pathogenic effect]

Molecular techniques have allowed the identification of new viruses in a number of patients with cryptogenic hepatitis. Whether they are clinically inapparent or true hepatitis agents remains unknown for some of them. Latest described viruses include GBV, TTV and SENV. However, based on the limited data available, they do not seem to be contenders for the new hepatitis virus title. However, researchers are looking for a role of these viruses in other chronic and acute human diseases. Only a careful evaluation of the data and the scientific concordance of all the evidence will resolve the question of whether they are only commensal viruses or pose a real pathogenic potential.

Advances in the diagnosis and management of human viral hepatitis

This article presents a comprehensive review of viral hepatitis types A through G and TTV. The information that is provided includes the definition, causes, signs and symptoms, diagnosis, pathogenesis, and acute and chronic forms of hepatitis. The modes of transmission, risk groups, morbidity and mortality, epidemiology, and treatment modalities are also presented. The primary objective for this extensive review is to provide dental health care workers with the most current information on the subject, which will allow them to identify the patients who will potentially have complications as the result of invasive dental treatment. By using this information, dental health care workers can be assured that they are practicing "state-of-the-art dentistry" while ensuring the health of their patients, staff, and families.

New hepatitis viruses: contenders and pretenders

Following the development of tests for hepatitis C virus and hepatitis E virus infection, it became clear that there remained cases of hepatitis that were non-A-E. Such cases provided impetus for the search for additional hepatitis viruses and, by using molecular techniques, several candidates were identified. An enteric agent responsible for sporadic non-A and non-E hepatitis was tentatively called hepatitis F virus. However, the lack of any corroborating reports has cast doubt on its status as a true hepatitis virus. Two groups independently reported the isolation of a blood-borne virus, designated as hepatitis G virus (HGV) and GB virus C (GBV-C) by their respective discoverers. They were later shown to be isolates of the same virus. While the virus has a high prevalence in cases of non-A-E hepatitis, it also has a high prevalence in the appropriate control groups and convincing evidence for its replication in the liver is lacking. Another possible hepatitis virus, TT virus, was discovered in the blood of a patient with post-transfusion non-A-E hepatitis. By using PCR primers designed to overcome the high nucleotide sequence divergence, TT virus was found to be ubiquitous with a worldwide distribution. A disease association is thus unlikely. Most recently, a DNA virus designated as SEN-V has been announced as a major cause of non-A-E hepatitis. Based on limited data available to researchers, SEN-V is the most convincing contender for the new hepatitis virus title. However, the lessons learnt from the hepatitis virus pretenders will need to be applied to SEN-V and any future contenders.

Hepatitis: still a concern?

Although some forms of viral hepatitis were identified more than 50 years ago, hepatitis continues to have an impact on the practice of dentistry. Possible transmission in the dental setting, management of the chronically ill, and legal issues related to treatment of infectious patients combine to emphasize that hepatitis is still an important issue for dental health care workers. Currently, 7 viral forms are recognized. Those with predominantly enteral modes of transmission--including HAV, HEV, and HFV--are of minor concern in the dental environment. HBV, the most infectious blood-borne pathogen, has been largely controlled in this country by vaccination and the use of universal precautions. HDV is an incomplete virus that has HBV infection as a prerequisite. HCV is of great concern today for several reasons. A high percentage of HCV infections results in chronic disease. Most cases remain asymptomatic for an extended period of time, and many have no identifiable risk factors. Currently, no vaccination is available for HCV. Patients infected with HCV present a management challenge, because they may ultimately develop serious liver dysfunction. In fact, HCV infection is presently the most common reason for liver transplantation. By understanding the various forms of viral hepatitis and following recommended infection control and vaccination protocols, the dental healthcare worker can treat infected patients in a manner that is safe for both patients and dental health care workers.

Hepatitis G virus: is it a hepatitis virus?

Hepatitis G virus (HGV) and GB virus C (GBV-C) are two newly discovered viral agents, different isolates of a positive-sense RNA virus that represents a new genus of Flaviviridae. The purpose of this review is to analyze new data that have recently been published on the epidemiology and associations between HGV and liver diseases such as posttransfusion hepatitis, acute and chronic non-A-E hepatitis, fulminant hepatitis, cryptogenic cirrhosis, and hepatocellular carcinoma. The role of HGV in coinfection with other hepatitis viruses, the response to antiviral therapy, and the impact of HGV on liver transplantation are also discussed. HGV is a transmissible blood-borne viral agent that frequently occurs as a coinfection with other hepatitis viruses due to common modes of transmission. The prevalence of HGV ranges from 0.9 to 10% among blood donors throughout the world and is found in 1.7% of volunteer blood donors in the United States. The majority of patients infected with HGV by blood transfusion do not develop chronic hepatitis, but hepatitis G viremia frequently persists without biochemical evidence of hepatitis. Serum HGV RNA has been found in 0 to 50% of patients with fulminant hepatitis of unknown etiology and 14 to 36% of patients with cryptogenic cirrhosis. The association between HGV and chronic non-A-E hepatitis remains unclear. Although HGV appears to be a hepatotrophic virus, its role in independently causing acute and chronic liver diseases remains uncertain.

GBV-C/HGV: a new human hepatitis-related virus

Two novel potentially hepatotropic flavi-like viruses were recently identified in patients with acute or chronic hepatitis and were provisionally called GBV-C and hepatitis G virus (HGV). The sequence identity analysis of these two viruses clearly indicated that GBV-C and HGV are two isolates of the same virus. In addition, the phylogenic analysis of the aligned viral polyprotein sequences showed that the GBV-C and HGV isolates are closely related to two Flaviviruses (GBV-A and GBV-B) that cause hepatitis in tamarins, and are distantly related to hepatitis C virus (HCV). Taken together, these results demonstrate that GBV-C/HGV belongs to the Flaviviridae family. GBV-C/HGV genomic RNA is detectable in both acute and chronic non-A, nonE hepatitis as well as in a minor proportion of patients with fulminant hepatic failure, hepatocellular carcinoma and in blood donors with or without abnormal alanine aminotransferase. However, the majority of patients with prospectively followed HGV infections have no evidence of liver damage. The high frequency of GBV-C/HGV infections in patients who are coinfected with HBV and/or HCV suggests that these viruses can share a common mode of transmission.

GB virus C/hepatitis G virus and other putative hepatitis non A-E viruses

The identification of the major agents causing human hepatitis (Hepatitis A, B, C, D and E Viruses) was achieved during the last 30 years. These viruses are responsible for the vast majority of human viral hepatitis cases, but there are still some cases epidemiologically related to infectious agents without any evidence of infection with known virus, designated as hepatitis non A-E. Those cases are considered to be associated with at least three different viruses: 1--Hepatitis B Virus mutants expressing its surface antigen (HBsAg) with altered epitopes or in low quantities; 2--Another virus probably associated with enteral transmitted non A-E hepatitis, called Hepatitis F Virus. Still more studies are necessary to better characterize this agent; 3--Hepatitis G Virus or GB virus C, recently identified throughout the world (including Brazil) as a Flavivirus responsible for about 10% of parenteral transmitted hepatitis non A-E. Probably still other unknown viruses are responsible for human hepatitis cases without evidence of infection by any of these viruses, that could be called as non A-G hepatitis.

Histopathological aspects of viral hepatitis

The main method of classification of chronic viral hepatitis is now by cause, and the old histology-based classification is no longer considered appropriate. However, liver biopsy remains an important part of patient assessment and, in the context of clinical trials, biopsy findings are often scored in a semiquantitative manner. The concepts of grading and staging, borrowed from tumour pathology, have been introduced, representing the severity of the necroinflammatory lesion and the extent of its structural consequences respectively. The pathology of the individual forms of viral hepatitis A to G shows more similarities than differences. However, some pathological features are commonly associated with specific viruses. The combination of portal lymphoid follicles, bile duct damage, lobular activity and steatosis give chronic hepatitis C a characteristic histological profile. Very similar appearances have been noted in the limited number of biopsies so far reported from patients with known combined hepatitis C and G virus infection.

Serologic diagnosis of viral hepatitis

Viral hepatitis has become a difficult field in which clinical and laboratory skills are needed to establish the correct diagnosis and plan for the appropriate therapy. For example, it is no longer enough to diagnose chronic hepatitis B or C. Now, the viral titer or viral genotype must be known. The laboratory test then must be understood in the context of the clinical presentation. This article helps the clinician to acquire such working knowledge. It summarizes available data for hepatitis A, B, C, D, and E. It also includes the recently discovered viral agents, hepatitis G and the hepatitis GB agents.

Molecular cloning and disease association of hepatitis G virus: a transfusion-transmissible agent

An RNA virus, designated hepatitis G virus (HGV), was identified from the plasma of a patient with chronic hepatitis. Extension from an immunoreactive complementary DNA clone yielded the entire genome (9392 nucleotides) encoding a polyprotein of 2873 amino acids. The virus is closely related to GB virus C (GBV-C) and distantly related to hepatitis C virus, GBV-A, and GBV-B. HGV was associated with acute and chronic hepatitis. Persistent viremia was detected for up to 9 years in patients with hepatitis. The virus is transfusion-transmissible. It has a global distribution and is present within the volunteer blood donor population in the United States.

New hepatitis viruses: are there enough letters in the alphabet?

Testing is now available for five recognised hepatitis viruses (A, B, C, D and E), and molecular technology is uncovering further hepatotropic viruses. An enteric agent isolated from human stool samples and transmitted experimentally to primates is a candidate hepatitis F virus. A provisionally designated blood-borne hepatitis G virus is associated with acute and chronic non-ABCDE hepatitis and has a worldwide distribution. A group of flavi-like viruses, the GB group, also blood borne, has also been reported. The role of two of these viruses, GBV-A and GBV-B, in human viral hepatitis has not been determined, but a third agent, GBV-C, is associated with acute and chronic hepatitis and appears to be a West African variant of hepatitis G. Our current knowledge suggests that the hepatitis alphabet may need to be extended even after inclusion of some of these new viruses.