Answer: Hepatitis B virus infects hepatocytes; immune response (cytotoxic T cells) attempting to kill infected cells causes hepatocyte damage; chronic infection leads to cirrhosis and hepatocellular carcinoma.
- A Hepatitis B virus is understood to directly destroy infected liver cells without any involvement from the host immune system, through a cytopathic mechanism similar to that seen in poliovirus infection
- B Hepatitis B virus infects hepatocytes; immune response (cytotoxic T cells) attempting to kill infected cells causes hepatocyte damage; chronic infection leads to cirrhosis and hepatocellular carcinoma
- C Hepatitis B is in fact correctly classified by microbiologists as a bacterial disease rather than a viral disease, responding largely to standard antibiotic therapy in every infected patient
- D Hepatitis B infection is understood to mainly ever cause a short-lived, self-resolving acute illness, rarely a chronic disease, with the virus being largely cleared from the liver within a few weeks
Correct answer: B. Hepatitis B virus infects hepatocytes; immune response (cytotoxic T cells) attempting to kill infected cells causes hepatocyte damage; chronic infection leads to cirrhosis and hepatocellular carcinoma
Explanation: HBV (hepadnavirus, DNA virus): infects hepatocytes → CTLs attack infected cells → inflammation → liver damage. Most adults clear it (acute hepatitis); 5% become chronic carriers → chronic hepatitis → cirrhosis → hepatocellular carcinoma (HCC). HBsAg persists in chronic infection. HBV is 100x more infectious than HIV. Vaccine available (3-dose schedule).
The Plasmodium parasite needs both hosts: the female Anopheles mosquito injects sporozoites while biting (infecting the human liver and RBCs, causing the malaria fever cycle), then picks up gametocytes from an infected person's blood, completing the parasite's sexual stage inside the mosquito.
Concept context
Pathogens, infectious diseases, non-infectious diseases, drugs, cancer, and public health. High NEET importance.