INTRODUCTION TO HEPATITIS D VIRUS (HDV)
⇒ HDV was identified in 1977 by Rizzetto & colleagues in the liver cell nucleus, as a new viral particle, of the patient infected by HBV and named as Hepatotropic virus Delta or Hepatitis D virus (HDV).
⇒ HDV is a defective virus as it depends on the helper function of HBV for its replication and expression.
⇒ HDV causes Type D Hepatitis & has no independent existence and can survive and replicate as long as HBV infection persists in the host.
MORPHOLOGY OF HEPATITIS D VIRUS (HDV)
⇒ HDV belongs to Deltavirus genus.
⇒ HDV is a Spherical particle surrounded by HBsAg Envelope.
⇒ Size – 36 – 38 nm in diameter.
⇒ Genetic material – Circular ssRNA, encodes its own nucleoprotein, the delta antigen or HDAg.
TRANSMISSION ROUTE OF HEPATITIS D VIRUS (HDV)
⇒ Transmission route of HDV is same as for HBV:- Parenterally by Blood, Saliva, Breast Milk, Semen, Vaginal Secretions, Urine, Bile & Feces; Sexually & Congenitally.
CLINICAL FEATURES OF TYPE D HEPATITIS
⇒ The incubation period is long, about 1 – 6 months.
⇒ Co-infection: In this, the HDV & HBV are transmitted together at the same time. Co-infection clinically presents as acute hepatitis B, ranging from mild to fulminant disease.
⇒ Superinfection: In this, HDV infection occurs in a person already harboring HBV, which usually leads to more serious & chronic illness.
⇒ No association has been noted between HDV & Hepatocellular carcinoma.
LABORATORY DIAGNOSIS OF HEPATITIS D VIRUS (HDV)
⇒ Detection of IgM anti-delta Antibody in serum by ELISA or RIA.
⇒ HDAg is primarily expressed in liver cell nuclei where it can be detected by immunofluorescence.
PROPHYLAXIS OF HEPATITIS D VIRUS (HDV) INFECTIONS
⇒ No specific prophylaxis is available.
⇒ Immunization with the hepatitis B Vaccine is effective because delta antigen cannot infect person immune to HBV.
⇒ Screening of blood donors for HBsAg will also limit the blood-borne HDV infection.
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