What are the hiv tests

HIV is the abbreviation of AIDS, which is an infectious disease that can endanger human life. The number of patients has tended to increase in recent years. Therefore, HIV prevention and treatment need to be strengthened. AIDS is an immune disease that can cause a person's immune system to collapse, so HIV testing is very important.

What are the HIV tests?

1. Antibody testing

The main ones are enzyme-linked immunosorbent assay (ELISA) and immunofluorescence assay (IFA). Rapid test method, also known as gold standard method, is also a method of antibody detection. It is used for qualitative detection of HIV antibody based on the principle of immunochromatography.

2. Antigen detection

When using ELISA to detect P24 antigen, the antigen is present in the blood in the early stages of HIV infection when antibodies have not yet appeared. Since the amount of P24 is too small, the positive rate is usually low. Currently, the sensitivity is improved by using the dissociation immune complex method or concentrating the P24 antigen.

3. Nucleic acid testing

The PCR method for detecting HIV genes has the advantages of being rapid, efficient, sensitive and specific. Currently, this method has been used in the early diagnosis of HIV infection and in the research of AIDS.

4. Virus Isolation

The commonly used method is the co-culture method, which is to separate mononuclear cells from normal human peripheral blood, stimulate them with PHA and culture them, and then add them to the patient's mononuclear cells for diagnosis and AIDS research.

5. ELISA

That is "enzyme-linked immunosorbent assay", abbreviated as ELISA. Its core is to allow antibodies to bind to enzyme complexes and then detect them through color development. The steps are actually very simple: ELISA uses serum for testing. First, the blood must undergo at least half an hour of agglutination, and then the serum is taken (this is why some netizens don’t understand why the hospital ignores the blood after drawing it, which is actually a misunderstanding). After the enzyme complex is diluted with diluent, add serum and negative and positive controls, as well as quality control products (this is a strict requirement and its range must be within the quality control range). After one hour of incubation, wash the plate, add substrate, and after half an hour of reaction in the dark, add the stop solution to complete the reaction part, and then read the results. The result is determined to be negative or positive by the numerical value. Strictly speaking, if the first test is positive, no matter which laboratory, a second test must be conducted according to the CDC HIV operating procedures. The second method must be different from the first. If it is still positive, it will be sent to the AIDS confirmation laboratory for confirmation.

6. Quick method

The gold label method, also known as the colloidal gold method, is an internationally advanced in vitro diagnostic method that is sensitive, specific, rapid, simple and highly accurate. The test results can be obtained in a short time using only a special test strip. Gold label method (AIDS test strip): take blood and drop it on the test strip, and observe whether the test strip changes color for 15 minutes.

The rapid HIV test can be done at home. It is simple and convenient to operate and does not require special instruments. First, drop two drops of blood on the HIV test paper, then drop one drop of diluent, and then wait 15 minutes to read the result. The results are also very simple to interpret. If there is a straight red line on the test paper, it means it is negative. If there are two red lines, it means it is positive. If the test result is positive, retesting is required according to the HIV testing process.

Self-testing for HIV using rapid methods (HIV test strips) should be conducted under the guidance of professionals to ensure that the entire self-testing process is standardized and correct, and the results are accurate and reliable.

7. Western Blot (WB)

This method is commonly used in AIDS diagnosis laboratories and is mainly used for confirmation tests. When the initial screening result is positive, this method needs to be used for confirmation tests. The basic principle is that the whole HIV virus antigen is subjected to SDS-PAGE electrophoresis to separate protein bands of different molecular weights, and then these separated different proteins are transferred to the nitrocellulose membrane with charge. The membrane is cut into strips, and each strip of nitrocellulose membrane contains HIV virus antigens separated by electrophoresis. The serum sample to be tested is diluted to 1/100 with diluent, and then added directly to the nitrocellulose membrane and shaken at a constant temperature to allow it to fully contact and react. If the serum contains anti-HIV antibodies, it will combine with the antigen bands on the membrane strip. After adding anti-human IgG enzyme conjugate and substrate, the reactive antigen-antibody binding band will appear purple-brown, and the result can be determined based on the appearance of the bands. It has been reported that the specificity of the Western blot test is not very good, with a false positive rate of about 2%, but the Western blot test is still the most commonly used HIV confirmation test.