Hepatitis A Virus: Structure, Pathogenesis, and Diagnosis

By Ashma Shrestha •  Updated: 05/19/22 •  8 min read

Inflammation of hepatocytes (liver cells) is termed hepatitis. The major cause of hepatitis is a viral infection but other causes include excessive consumption of alcohol, toxins, different medications, and autoimmune disorders.

Hepatitis can be classified based on transmissibility into two classes:

  1. Infectious (viral hepatitis): These include acute Hepatitis caused by hepatitis viruses (A, B, C, D, E, and G) and chronic infection by hepatitis B, hepatitis C, and hepatitis D viruses.
  2. Non-infectious: Usually, this infection is caused by autoimmune disorders, excessive alcohol consumption, medications, and ingestion of toxins.

Hepatitis A is a fecal-oral transmitted infection often acquired through contaminated food and water. Hepatitis A virus (HAV) causes infectious hepatitis. It is a subacute disease of global distribution, which affects mainly children and young adults.

Morphology of Hepatitis A Virus

Structure of Hepatitis A

Genomic arrangements

Genomic arrangement of HAV

Replication of Hepatitis A Virus

Cell entry

Uncoating of viral material

After the entry, the RNA genome is released inside the cell maybe along with the capsid.

Protein synthesis

RNA synthesis

Virion assembly

The detailed process of assembly of viral particles is less known. But the location of assembly is at the plasma membrane of the host cell.

Replication of HAV

Pathogenesis

Transmission

Virulence factors

Incubation period

The incubation period ranges from15-45 days, but sometimes may stretch to 4 weeks.

Mortality rate

The mortality rate of HAV infection is <0.01%. 

Symptoms

Laboratory diagnosis of HAV infection

Specimen

Collection and Transport of Stool
Collect the stool in a sterile, leak-proof, and dry container. Preferred amount is 10cc/ml of diarrheal sample. The patient is instructed to collect stool in sterile conditions. As per feasibility and transported to the laboratory within the first 1 hour of collection. If delayed, refrigeration at 4℃ or collection should be done in a container with a viral transport medium.
Collection and Transport of Blood for serum
A serum sample from the same patients is ideal for the correct diagnosis. Blood (15ml from adults and 3ml from children) is drawn aseptically in a tube without anticoagulant. Centrifuge the blood sample in 1000-2000g for 10 minutes. The separated serum sample is then processed. If there is a delay in processing the sample, refrigerate at 4℃ (do not freeze the sample).


(NOTE: if centrifuge is not available, the blood is refrigerated until a clot is formed, the serum is then pipetted into an empty sterile tube and transported to the laboratory as soon as possible.)

Sample processing

Sample process is done by following ways:

Microscopy

An electron microscope can detect viral material in fecal matters of the suspected individuals.

Virus Isolation

Although virus isolation in human cell lines possible, it is not applicable during routine diagnosis. But useful in research purposes.

Antigen detection

Serology

Molecular Diagnosis

Detection of the nucleic acid of HAV is done in following ways:

Other methods of detection of hepatitis:

Prevention and Control

No antiviral therapy is necessary only the treatment of symptoms is enough.

Vaccine

Preferably two doses of vaccine at the interval of 6-18 months. There was an anamnestic response when the second dose was taken after several years. Because of this, the timing of the second dose is very crucial.

Prophylaxis with immunoglobulin

Post-exposure immunoglobulin within 2 weeks is recommended in those who are in immediate contact with the infected patients.

The preferred way of administration is a dose of 0.02ml intramuscularly. 

Preventing spread

The best way to control the infection is to maintain the cleanliness of drinking water and food by regularly cleaning the water sources, avoiding raw foods, and maintaining personal hygiene. 

References:

Ashma Shrestha

Hello, I am Ashma Shrestha. I am currently pursuing my Master's Degree in Microbiology. Passionate about writing and blogging. Key interest in virology and molecular biology

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