Diagnosis of HIV
Case: One of a clinic sent a patient to our laboratory to make diagnosis of HIV.
Step 1: Collection of blood.
1 – In our phlebotomy room, we have collected two blood samples one to get a serum and another to get plasm.
Step 2: ELISA (serum for screening).
1 – We used in our laboratory an instrument called Architct PLUS, and it gave us a positive result of HIV.
2- – The principle of instrument:
– Direct solid phase antiglobulin ELISA is the method most commonly used. The antigen is obtained from HIV grown in continuous T- lymphocyte cell line or by recombinant techniques and should represent all groups and subtypes of HIV-1 and HIV-2. The antigen is coated on the microtitre wells or other suitable solid surface.
The test serum is added. And if the antibody is present, it binds to the antigen.
– After washing away the unbound serum, antihuman immunoglobulin linked to a suitable enzyme is added. If test serum contains anti-HIV antibody, a photometrically detectable colour is formed which can be read by special ELISA readers.
3- – do another confirmation test which is Western Blot”
Step 3: Western Blot (plasma for conformation).
1- – Western Blot test gave us also a positive result of HIV.
2- The principle of Western Blot test:
– In this test HIV proteins separeated according to their electrophoretic mobility(and molecular weight) by polyacrylamide gel electrophoresis are blotted onto strips of nitrocellulose paper. These strips are reacted with test sera and then with enzyme conjugated antihuman globulin.
– A suitable substrate is then added, which produces a prominent colour band where the specific antibody has reacted with the separated viral protein.
– A positive reaction with proteins representing the three genes gag,pol,env is considered positive even if it shows bands against at least two of the following gene
Final report is:
The patient has infected with HIV, and we used two different test and which all of them gave us a positive result.
Diagnosis of HIV