4. Hepatitis B Virus Deoxyribonucleic Acid and Deoxyribonucleic Acid Polymerase

4. Hepatitis B Virus Deoxyribonucleic Acid and Deoxyribonucleic Acid Polymerase

Hepatitis B Virus deoxyribonucleic acid (HBV-DNA) is the basic substance that constitutes the virus; a positive result in serum testing indicates viral replication. Using molecular medicine dot-blot hybridization technology to examine Hepatitis B Virus deoxyribonucleic acid is one of the most advanced methods today and is currently considered the most sensitive method.

Hepatitis B deoxyribonucleic acid polymerase (DNA-P) is an indicator of viral replication. It is mostly positive during the acute phase of acute hepatitis B, and some cases of chronic active hepatitis may also test positive. Generally, this enzyme exists in the body for a relatively short period: about 2–4 weeks during the acute phase, and longer during the chronic phase.

III. Routes of Transmission of Hepatitis B

Previously, it was believed that the transmission routes of hepatitis B were mainly through blood transfusions, blood products, injections, vaccinations, and other blood-related systems. However, according to recent surveys and studies by many scholars, only 2%–4% of infections resulted from these routes. The largest proportion of infections, however, comes from gastrointestinal transmission, known as horizontal transmission, accounting for about 55% of all hepatitis B infections. Since most adults infected through horizontal transmission can successfully clear the virus from their bodies, scholars now believe that the actual infection rate of hepatitis B in China is about 70% of the population, while the incidence rate is only around 5%–25%. This indicates that among those who actually develop hepatitis B, horizontal transmission does not constitute the majority; vertical transmission is far more common. Specifically, if the mother carries HBV and her HBeAg is positive, 90% of her children will be infected; if the father carries HBV, 20% of his children may be infected. Vertical transmission is much harder to clear on its own, leading to the development of hepatitis B patients, so the prognosis of vertical transmission is completely different from that of horizontal transmission. According to surveys, there are about 100 million HBsAg carriers in China. Recent liver biopsies have revealed that 90.14% of these carriers have varying degrees of pathological changes in their liver tissue, while only 9.80% show no obvious pathological changes. Among the former, 68.23% have chronic persistent hepatitis, 10.4% have chronic active hepatitis, and only 11.46% have mild changes; some patients even show signs of cirrhosis. This indicates that the so-called "healthy carriers" are merely chronic hepatitis B patients with inconspicuous clinical symptoms. Some have followed up with "healthy carriers" and found that about 5% of them experience symptom flare-ups due to factors such as fatigue, alcohol consumption, and emotional stress within a year. Such active hepatitis should not be regarded as acute hepatitis. Hepatitis B primarily affects children and young adults, with fewer cases among the elderly. Domestic and international statistics show a male-to-female ratio of about 2:1.

IV. Diagnosis of Hepatitis B

The diagnosis of hepatitis B should be based on comprehensive analysis of epidemiological data, symptoms, physical signs, changes in liver function, and etiological examinations, while ruling out other diseases. Although liver biopsy provides more accurate results, it is difficult to implement widely in clinical practice, so the diagnosis of hepatitis B mainly relies on the aforementioned methods. In December 1984, the Nanning Conference on Viral Hepatitis revised the "Viral Hepatitis Prevention and Control Plan," stating that the diagnostic nomenclature for viral hepatitis should include both etiological classification and clinical classification, such as "viral hepatitis, type B, chronic active non-jaundiced type."