HAV Structure and Types
Hepatitis A virus or HAV is a single-stranded with positive-polarity RNA virus, which belongs to the genus Hepatovirus of the Picornaviridae family. The virus is a non-enveloped and icosahedral symmetry shape with a diameter ranges from 27 to 32 nm in size. So far, seven HAV genotypes have been identified by the experts. Four genotypes (I, II, III, and VII) are of human origin, and three (IV, V, VI) are of simian origin. Genotypes I and III are the most prevalent genotypes isolated from humans.
Hepatitis A virus Stability
HAV in-vitro culture needs a long adaptation period. It rarely produces cytopathic effect because the HAV replication period is a slow process in the cell culture medium. However, it is stable in the environment for a month and it is more resistant to heat. Physically inactivation involves heating of foods to more than 85°C for 1 min and disinfection of surfaces requires 1 min of contact with a 1:100 dilution of sodium hypochlorite.
How Do You Diagnose Hepatitis A?
Detection of HAV-Specific Antibodies
The humoral immune response has a significant role in the diagnosis of HAV infection and the differentiation of hepatitis A from other types of viral hepatitis. There are a number of commercially available assays for the detection of antibodies against HAV infection. IgM antibody is only present in the blood following an acute hepatitis A infection. It is detectable from 1 to 2 weeks after the initial infection and persists for up to 14 weeks. Diagnostically, IgM anti-HAV has been used as the primary marker of acute infection. The presence of IgG antibodies in the blood means the acute stage of the illness has passed and the person is immune to further infection. IgG antibodies to HAV are also found in the blood following vaccination, and tests for immunity to the virus are based on the detection of this antibody.
Immunological and Biochemical Techniques for Hepatitis A Virus Diagnosis
A number of methods have been used to detect this virus-specific antibody such as radioimmunoassay, immunochemical staining, enzyme-linked immunosorbent assay, immunoblotting, and dot blot immunogold filtration. In the course of the acute stage of the infection, the liver enzyme alanine transferase is present in the blood at levels much higher than is normal. Alanine aminotransferase test is to confirm the HAV infection and its liver disease or injury.
Hepatovirus A can survive in the blood and feces of infected people up to 2 weeks before the clinical illness develops. HAV can be visualized in fecal extracts by electron microscopy. During outbreaks, the electron microscopy microscopic analysis could be a helpful technique for detection of HAV virus in water samples and fecal extracts.
Hepatitis A virus nucleic acid (genetic material) detection techniques are more sensitive than biochemical and immunoassays for the viral antigen to detect HAV in samples of different origins. It is usually done with the help of Polymerase chain reaction (PCR). Clinical specimens, environmental samples, and food samples can be used for HAV detection during outbreaks. Amplification of viral RNA by RT-PCR (Reverse Transcriptase-PCR) is currently the most sensitive and widely used method for detection of HAV RNA.
Treatment for Hepatitis A Virus
There is no specific treatment at present for HAV infection. The human body will clear the hepatitis A virus on its own and in most of the cases, the liver heals within six months with no lasting damage. Rest, fluid intake, avoid alcohol, clean hygiene, and mild diet can recover person which may take several weeks or months. Hepatitis A can be prevented by vaccination, good hygiene, and proper sanitation. The CDC-USA recommends a hepatitis A vaccine for the following individuals.
- Children at the age 1, or older children who didn’t receive the childhood vaccine
- Laboratory workers who may come in contact with hepatitis A
- Men who have sex with men
- People with other risk factors who work or travel in parts of the world where hepatitis A is common
- People who use any type of illegal drugs, not just injected ones
- People who receive treatment with clotting-factor concentrates
- People with the chronic liver disease.
- Hepatitis A: Signs, Symptoms, Diagnosis, Prevention, Treatment, Prognosis
- Is Hepatitis A and E Contagious?
- What Are The Side Effects Of Hepatitis A Vaccine?
- How Long Is a Person With Hepatitis A Contagious To Others?
- How Do You Know You Have Hepatitis A?
- Can You Be Cured of Hepatitis A?
- How Is Hepatitis A Caused?
- Can a Person Die from Hepatitis A?