Hepatitis viruses. Features of structure and main biological properties

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Hepatitis viruses. Features of structure and main
biological properties
Vinnitsa National Pirogov Memorial Medical
University / Department of microbiology
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• The term viral hepatitis refers to a primary
  infection of the liver by any one of a
  heterogeneous group of hepatitis viruses. It
  consists of types A, B, C, D, E, G.
• Hepatitis viruses are taxonomically unrelated
  (DNA and RNA viruses). The features common to
  them are
• hepatotropism
• ability to cause a similar icteric illness

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By epidemiological and clinical criteria, two
types of viral hepatitis had been recognised for
long

• A first type (this type was called infective or
  infectious hepatitis)
• Occurred sporadically or as epidemics
• Affecting mainly children and young adults
• Transmitted by the fecal-oral route.
• A second type (this type had been given various
  names such as serum hepatitis or transfusion
  hepatitis) transmitted mainly by parenteral route

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Type A virus hepatitis (HAV)

• Belongs to the Picornaviridae family
• Morphology.
• HAV is a spherical ss()RNA-including virus
• 27-30 nm in diameter
• Non enveloped

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Classification of viral hepatitis

• Hepatitis A virus
• Hepatitis B virus
• Hepatitis C virus
• Hepatitis D virus
• Hepatitis E virus
• Hepatitis G virus

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HAV is transmitted by the fecal-oral route

• Pathogenesis
• The clinical disease consists of two stages the
  prodromal (or preicteric) and the icteric stage

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Laboratory diagnosis

1. IEM
2. Serology
3. Detection of viral antigens in stool samples

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Prophylaxis

• General prophylaxis consists of
• Specific prophylaxis
• Active
• Passive
• Treatment is symptomatic. No specific antiviral
  drug is available

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• Type B hepatitis (HBV)

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Antigen Structure

• HBsAg
• HBcAg
• HBeAg
• HBxAg

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There are three important modes of transmission
of HBV infection parenteral, perinatal, sexual

• Laboratory diagnosis
• Detection of hepatitis B antigens and antibodies
  (viral markers).

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Prophylaxis

• Prophylaxis includes
• General preventive measures
• Immunisation
• Passive
• Active.

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Type C hepatitis (HCV)

• Hepatitis C virus belongs to the family
  Flaviviridae
• HCV is a 50-60 nm virus with a linear single
  stranded RNA of positive polarity (ss()RNA)
• Enclosed within a core and surrounded by an
  envelope, carrying glycoprotein spikes

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Laboratory diagnosis

• It can be established by detection of anti-HCV by
  ELISA.
• Viral genome (HCV RNA) detection

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Type D (Delta) hepatitis (HDV)

• HDV is a defective RNA virus depending on the
  helper function of HBV for its replication and
  expression. It belongs to genus Deltavirus

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Its mode of transmission is the same as for HBV

• Two types of infection are recognized
• Coinfection
• Superinfection

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Laboratory diagnosis

• Delta antigen
• Anti-delta antibodies