Surface antigen 1 mainly appears in the serum after hepatitis B virus infection 1-2 months. It can last for weeks, months to years, or it can exist for a long time.
Positive surface antigen indicates that there is hepatitis B virus in the liver. Surface antigen itself is not contagious, but it is often regarded as one of the signs of infectivity because it coexists with viruses.
The positive detection of HBV DNA is a reliable diagnostic index of acute HBV infection.
4. Comprehensive evaluation of HBV DNA test results and serum immunological results (i.e. 2 and a half minutes).
1) and surface antigen test results: Generally speaking, surface antigen is positive, and DNA test is often positive. The problems that may be encountered in practice are negative surface antigen and positive DNA. The reason is that the sensitivity of the two halves is low, and the surface antigen with low concentration is not large. The sensitivity of DNA detection is extremely high, even if the DNA content of hepatitis B is very low, it can be detected. Or in the early stage of hepatitis B virus infection, when all immune markers (two halves) are not produced.
2) Relationship with surface antibody: During the recovery period of hepatitis B virus infection, surface antibody is positive, serum HBV DNA test is usually negative, but a few of them can be positive, especially the positive rate of HBV DNA test in liver tissue is still very high, indicating that the virus has not been completely eliminated from the liver. Only negative HBV DNA test is a clear indicator of virus removal.
3) Relationship with E antigen (HBeAg), E antibody (HBeAb) and core antibody (HBcAb): E antigen is positive, and almost all DNA tests are positive; However, patients with negative E antigen, positive E antibody and positive core antibody (that is, patients with small three positive) only show that virus replication is weakened, but it has not completely disappeared, and the positive rate of serum DNA can still be as high as 80%. Therefore, the detection of HBV DNA is a reliable index to evaluate the infectivity of hepatitis B.
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