Sample collection and laboratory test
Respiratory samples (throat swabs) were collected from the included ARIs
patients within 24 h of hospitalization. Professional staff will rotate
the nasopharyngeal swab back and forth 2 to 3 times, then quickly remove
the swab and put it into the microbial test tube containing sterile
normal saline. Those without phlegm will be atomized and attracted, and
the specimen will be immediately sent to the laboratory two hours after
collection.
RSV, ADV, Flu A and B, and PIV1,
2, and 3 were detected by direct immunofluorescence technique. The
rapid test kit is provided by Shanghai Haide Diagnostic Co., LTD. (lot
number: 186325). The specific detection principle and results were
determined as follows: the nasopharyngeal secretions were repeatedly
blown with a capillary straw and transferred to a centrifuge tube at the
tip base, centrifuged at (400 ~ 600)×g for 5
~ 10min to remove the supernatant and leave
precipitation. It is used to add 1 drop of corresponding fluorescent
antibody to each cell point of the specimen or photo, incubate in a 37.0
℃ temperature box for 30min, and then add 1 drop of blocking solution
after washing with washing liquid, and observe the results under a
fluorescence microscope after sealing the piece. The FITC-labeled
virus-specific monoclonal antibody binds to the corresponding viral
antigen in the cell to form an antigen-antibody complex. Under the
fluorescence microscope, the cells show apple green fluorescence and the
negative film is stained red by Evans blue. If two green fluorescent
cells are found in each field of vision under the microscope at 200
times, it is positive.