1. What are China's requirements for AIDS reagents?
HIV antibody detection reagents are divided into two types: preliminary screening reagent and confirmation reagent (including domestic or imported). Both of them must be HIV1+2 hybrid type, approved or registered by the State Drug Administration, and passed the batch inspection of the China Food and Drug Control Institute, and within the validity period. The reference laboratory of the National AIDS Prevention and Control Center conducts clinical evaluation of HIV antibody screening diagnostic reagents every year, and regularly publishes the reagent evaluation results. The reagents used by each HIV antibody testing laboratory must have the approval document and batch test report of the State Drug Administration, and try to select the kit with good evaluation quality.
2. What are the commonly used reagents in China?
HIV antibody detection method consists of preliminary screening test and confirmation test, which can only be carried out in the confirmation laboratory with HIV confirmation qualification. There are many methods for preliminary screening test, including solid phase enzyme-linked immunosorbent assay (ELISA), gelatin particle aggregation test (PA), latex particle aggregation test (LA), rapid method, etc. The common method is ELISA double antigen sandwich method.
Western blot (WB) is commonly used in the confirmation experiment. If the result of the primary screening test is positive, two reagents with different principles should be used for retest. If both are positive or one negative and one positive, further confirmation tests should be performed to make a clear diagnosis.
3. What are the advantages and disadvantages of rapid detection reagents?
Rapid method is one of the commonly used methods at present, mainly including selenium labeling method and gold labeling method. Compared with ELISA, the rapid method requires less time, and generally produces results in half an hour. It is suitable for the detection of a single sample, without additional reagents or equipment, and is easy to operate. Some reagents can also be stored at room temperature (ELISA must be stored at 2~8 ℃). The disadvantage is that there is a certain gap between the specificity and sensitivity of the rapid method and ELISA, and the rapid method is more expensive than ELISA.
4. What are the conditions for HIV antibody testing?
In accordance with the requirements of the National Code of Practice for AIDS Testing, all institutions engaged in HIV antibody testing must meet the following conditions:
(1) Approved by the provincial health administrative department;
(2) Have a special laboratory and separate the clean area from the polluted area;
(3) Have more than 2 inspectors who must pass the national or provincial training;
(4) Have necessary instruments and equipment, such as enzyme marker, plate washer, refrigerator, pipette, etc.
5. Which institutions can do HIV antibody testing
Disease control centers (or health and epidemic prevention stations), frontier health and quarantine institutions, blood stations and blood centers at all levels, and hospitals with the qualification for HIV antibody laboratory screening in all provinces, autonomous regions, and municipalities directly under the Central Government can be engaged in HIV antibody testing. Other testing institutions in all provinces, cities, and regions can ask the above units. At present, most provinces and cities have a confirmation laboratory, generally located in the provincial disease prevention and control center, which is responsible for the review and confirmation of positive samples in the province. The above institutions also provide consultation on AIDS when providing HIV antibody testing, including telephone consultation, letter consultation and outpatient consultation.
6. Whether the negative test result indicates no infection
For those with negative test results, the counselor should carefully verify the time of the last possible exposure to HIV in order to calculate whether the window period has passed. ". If the "window period" has passed, it can be determined that they are not infected, but they should be encouraged to change their behavior and discuss with them feasible ways to reduce the risk of infection. For those who do not believe in negative results and repeatedly consult and test, it is best to suggest that they seek psychological support from specialized agencies. If the "window period" has not yet passed, a review should be conducted after the "window period". Because infected persons may present negative results in the process of seroconversion of antibodies, but they are highly infectious at this time, the consultant should advise them to take corresponding preventive measures like infected persons, and analyze with them the obstacles they may encounter in the process of behavior change, so as to help them change their behavior, avoid infecting others and protect themselves from other infections. While waiting for the review, they may have various psychological problems, so they should be provided with follow-up support or introduced with information about support institutions, so that they can get timely help when needed.
7. Not sure what the result means
Uncertain results refer to the presence of protein bands on the test strip during the confirmation test of HIV antibody testing, but according to the requirements of the National AIDS Testing Work Specification, these bands are not enough to be diagnosed as HIV antibody positive. In case of uncertain results, it is recommended to review them after 3 months. If the re-examination result is positive, it indicates that the subject has been infected with HIV; If all the bands disappear during reexamination, it is negative, indicating that the subject is not infected; If the strip does not change or changes but is not enough to be diagnosed as positive during the reexamination, it should be re-examined after 3 months. If it is not enough to be diagnosed as positive after 3 months, it should be treated as negative.
8. What are the principles for the uncertainty of test results
(1) Infection is still in the window period: the time from HIV entering the body to detection is not long enough, so the serum has not formed a typical antibody reaction;
(2) AIDS progress to the end stage, antibody levels decline;
(3) There is HIV 2 type or other subtypes (such as subtype 0), and the detection reagent used cannot be detected;
(4) Cross-reaction of other non-viral protein antibodies: in the case of autoimmune diseases, some malignant diseases, pregnancy, blood transfusion or organ transplantation, the body can produce some antibodies, and the reaction is very similar to that caused by HIV-P24 core protein antibody;
(5) Previously vaccinated with HIV (experimental) vaccine.