Hepatitis G Virus (HGV)
The HGV agent is an RNA virus belonging to the family Flaviviridae (the same family as the hepatitis C virus). It is important to emphasize that it is not a simian virus.
The clinical significance of HGV lies in its ability to cause severe and rapidly progressive forms of infection.
- Superinfection: When HGV infection occurs against the background of preexisting liver damage, the acute phase transitions to chronic hepatitis in 75% of cases.
- Severity of the process: In patients with severe chronic hepatitis, markers of active HGV replication are detected in the vast majority of cases — ranging from 79% to 86%.
- Pathogenesis: According to the working hypothesis, classical hepatitis B virus (HBV) often causes an infection with low to moderate activity. However, the addition of HGV acts as a trigger that dramatically increases the activity of the inflammatory process.
- Prognosis: HGV-associated infection is highly likely to lead to the rapid development of liver cirrhosis.
GB Agents (GBV-A and GBV-B)
A group of viruses designated as GBV was identified in the mid-1990s by a research team led by J.N. Simons. The discovery was made possible by applying representative differential analysis using PCR.
The history of their discovery is quite specific. Initially, the infectious agent was isolated from the blood serum of a surgeon (whose initials were G.B.) suffering from unverified hepatitis. This serum had been stored in a frozen state since the early 1960s. Subsequently, new viruses designated GBV-A and GBV-B were successfully isolated from the blood of a tamarin (a primate species) that was experimentally inoculated with the preserved GB agent.
DNA-Containing Hepatotropic Viruses: TTV and SEN
In the late 1990s, new viruses were discovered whose genome, unlike HGV and HCV, is represented by a DNA molecule.
| Feature | TTV (Transfusion Transmitted Virus) | SEN Virus |
|---|---|---|
| Year and place of discovery | 1997, Japanese researchers | 1999, Italian researchers |
| Nucleic acid type | DNA | DNA |
| Primary isolation source | Patients with post-transfusion hepatitis | HIV-infected patient with liver damage |
| Genetic diversity | 3 genotypes and 9 subtypes identified | No exact data within the scope of current review |
Characteristics of TTV: This virus is associated with cases of post-transfusion hepatitis. The clinical picture typically develops 8–11 weeks after a blood transfusion procedure. The main diagnostic marker is the detection of TTV-DNA. The virus has been isolated in the European part of Eastern Europe and Western Siberia, where it is found both in patients with hepatitis of undetermined etiology and in completely healthy individuals.
Characteristics of the SEN virus: According to Italian authors, the SEN virus has a specific prevalence among risk groups. It is detected in 3% of hemophilia patients, 40–60% of injection drug users, and 60% of patients with hepatitis of undetermined etiology.