There are generally two ways to detect COVID-19 virus, nucleic acid detection and antibody detection. But we generally talk about nucleic acid testing, and naturally ignore antibody testing. This is because antibody testing is generally used as a supplementary test indicator for suspected cases with negative COVID-19 nucleic acid testing or used in conjunction with nucleic acid testing in the diagnosis of suspected cases. It cannot be used as a basis for diagnosis and exclusion, and is more suitable for retrospective examinations. What is the difference between these two new crown tests? What kind of test is the disease-toxin preservation solution more suitable for?
Disease-venom preservation solution
It is a liquid used for the detection of virus samples. There are mainly two types: inactivated and non-inactivated. The inactivated type can quickly inactivate the virus-virus and release the virus-virus nucleic acid for rapid virus-virus nucleic acid detection; the non-inactivated type can protect the virus-virus RNA and protein activity at the same time, and can be used for virus-virus nucleic acid detection. , And can be used for antibody detection.
The difference between nucleic acid detection and antibody detection:
Different samples
Nucleic acid testing requires respiratory samples, including pharynx, nasopharyngeal secretions, sputum, bronchus, lavage fluid, lung tissue biopsy, etc. The collection process is very complicated.
Antibody testing is a blood test, which can be collected by peripheral blood or venous blood. The sample collection method is more convenient and safer, and the sample can be stored for 72 hours.
Different detection methods
Nucleic acid detection is a direct detection of viruses. It uses virus-specific DNA sequence as the detection target. Through PCR amplification, the target DNA sequence we choose increases exponentially. Each amplified DNA sequence can be labeled with a pre-added fluorescent label. The probe binds to produce a fluorescent signal. The more target DNA amplified, the stronger the accumulated fluorescent signal. In a virus-free sample, since there is no target DNA amplification, no increase in fluorescence signal can be detected. Moreover, the storage conditions of this nucleic acid sample are harsh, RNA is very easy to be lysed, and it can only be stored for 24 hours at 4°C.
The antibody test is an indirect test. It is not against the virus itself, but the specific antibody produced by the immune response after the human body is infected with the virus. Human body is infected with the virus-antibodies are gradually produced in about a week and then rapidly increase. Generally, the human body first produces antibodies called IgM. Positive IgM antibody indicates recent infection, and positive IgG antibody indicates longer infection time or previous infection.
Different detection conditions
Nucleic acid testing requires specialized instruments and standard molecular testing laboratories, and requires PCR-certified personnel to operate. The steps are cumbersome, and the whole process takes 5 to 8 hours, and the risk of contamination is high during the process.
Antibody detection Antibody detection breaks through the limitations of existing nucleic acid detection methods on personnel/locations. It can be tested quickly and in large quantities, and it can be completed in the primary laboratory, and the risk of contamination is small.
It can be seen that no matter what kind of new coronavirus detection method has advantages and disadvantages. Antibody testing is a supplement to the "false negative" of nucleic acid testing. The combination of the two can effectively improve the diagnostic efficiency of the new crown, which is of extraordinary value for epidemic prevention and control.