USMLE

Deltavirus

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Viruses - RNA Viruses
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Summary

Deltaviruses are viruses that use single-stranded, circular RNA. Additionally, their RNA is negative-sense, which means that the RNA must first be transcribed into mRNA before translation into proteins. Deltaviruses are also enveloped.

The most prominent deltavirus is the Hepatitis D Virus, or HDV. In order to replicate and enter cells, HDV requires the presence of HBV, which means that only patients previously infected with HBV can be infected with HDV. Patients infected with HDV experience hepatitis, and are at an increased risk for developing hepatocellular carcinoma or liver cancer.

Key Points

  • Deltaviruses
    • May be referred to as “delta agents”
    • Characteristics
      • RNA viruses
        • replicate in the cytoplasm of cells
        • Single-stranded
        • - sense
        • Circular
      • Enveloped
      • Unknown capsid symmetry
    • Presentation
      • Hepatitis D Virus (HDV)
        • Transmission
          • Parenteral (blood), sexual, perinatal
        • Pathogenesis
          • Replication defective; requires presence of HBV to replicate
            • Hepatitis D antigen requires HBV HBsAg coat for entry into hepatocytes
            • Superinfection (HDV on chronic HBV) → short course
            • Coinfection (HDV with acute HBV) → longer course
        • Presentation
          • Short incubation period
          • Hepatitis
            • Fever, jaundice, elevated ALT and AST
            • Chronic hepatitis can lead to cirrhosis and HCC
        • Diagnosis
          • HDAg - seen in acute infection
          • anti-HDV - seen in chronic infection
          • Diagnosis of HBV
          • Liver Biopsy
            • Similar to HBV
            • All viral hepatitis produce a similar histopathological pattern
              • Panlobular infiltrates, ballooning hepatocytes, hepatocyte necrosis, and hepatocyte apoptosis
              • Apoptotic bodies form round pink (eosinophilic) bodies known as Councilman bodies
        • Treatment
          • Pegylated interferon (PegIFN)