The term hepatitis B is not new to anyone, however, many people may not really understand it. Chronic hepatitis B, which can be referred to as chronic hepatitis B or slow hepatitis B, is caused by infection with the hepatitis B virus (HBV). So, what is the hepatitis B virus? Hepatitis viruses are a group of viruses that specifically attack the liver because the environment within the liver cells is conducive to the growth of hepatitis viruses; once they leave the liver cells, the viruses are inhibited from growing or even surviving. Humans have numbered these viruses in the order in which they were discovered, and the second one discovered was named hepatitis B virus (hepatitis B virus). The hepatitis B virus is mainly composed of proteins and DNA, of which the important proteins include surface antigen (HBsAg), core antigen (HBcAg), etc. We can think of hepatitis B virus as a lychee, the surface antigen (HBsAg) in the outermost layer is equivalent to the uneven shell of the lychee, the core antigen (HBcAg) in the middle is equivalent to the flesh of the lychee, and the hepatitis B virus gene (HBV DNA) in the inner layer is equivalent to the core of the lychee. When the hepatitis B virus invades the liver cells, it first has to shed the shell of surface antigen, which is soluble in water and flows with the blood, so we can check it during the blood test. A positive surface antigen is a sign that the hepatitis B virus is present. Next, the hepatitis B virus crosses the cell membrane and enters the liver cells. The core antigen of the virus (HBcAg) is not soluble in water, so it cannot be checked in the serum; however, the core antigen (HBcAg) will be degraded into the e antigen (HBeAg), which is soluble in water, so it can be checked in the serum. When the hepatitis B virus infects the body, it stimulates our immune system to produce antibodies against it – surface antibodies (HBsAb), core antibodies (anti-HBC), and e antibodies (HBeAb), which recognize the corresponding viral antigens. Surface antibodies (HBsAb), core antibodies (anti-HBC) and e antibodies (HBeAb) can all be detected in the serum, so the “two and a half pairs” can be detected by serological examination – the first pair is surface antigen (HBsAg), surface The second pair is e antigen (HBeAg) and e antibody (HBeAb), and the last half is core antibody (anti-HBC). We often refer to the major triple-positive: surface antigen (HBsAg), e antigen (HBeAg) and core antibody (anti-HBC) are all positive. The minor triple positive refers to: surface antigen (HBsAg), e antibody (HBeAb), and core antibody (anti-HBC) are all positive.