This is time for my sharing again. As I am currently attached to viral serology lab, I am learning different serological tests such as various enzyme immunoassays (EIA), hemeagglutination-inhibition tests (HI) and other specialized tests like immunoblots.
::Dengue In Focus
Since there were quit a number of dengue cases recently in Singapore, I think it would be useful to share how dengue is diagnosed.
Dengue virus can be isolated in the mosquito cell culture (C636 cell-lines) and specific dengue serotype can be identified using immunofluorescence method. Due to its specificity dengue isolation is the gold standard for dengue diagnosis. However viral isolation takes about 2 weeks.
Due to varies in its severity and undifferentiated symptoms, it is very important to diagnose dengue as early as possible and give appropriate treatments.
Therefore serodiagnosis of dengue which can detect dengue infection rapidly becomes the most common method. In this blog, I will be sharing about Dengue IgM Capture Enzyme-linked Immunosorbent Assay (ELISA).
::Dengue IgM ELISA
This particular dengue IgM kit uses Capture Enzyme-linked Immunosorbent method and specific dengue IgM is captured between anti-human IgM and commercial dengue antigen. The picture below clearly explains:
If O.D. reading is more than 1, it is considered as dengue IgM positive. Positive and negative control and calibrator added in each run for quality control. The assay is run 100% manually and takes about 4 hours.
Presence of dengue IgM shows that the patient is suffering from acute dengue infection as IgM are produced during the acute infection.
This test however cannot tell if the dengue infection is primary or secondary. Primary means this is the first time the patient is experiencing dengue infection. Secondary infection means patient had dengue before, but this time he/she is infected by dengue virus of different serotype from the first one.
Hemeagglutination-inhibition test is the only test which can determine the dengue infection is primary or secondary, acute, recent or recovering.
There are also commercially availiable rapid kits which uses various principles such as immunoblot, immunochromatographic, etc.
Well, I think this would be enough for this posting. Feel free to ask me if you have anything to clarify or wanna know more about dengue. All are welcome!
Thank you for reading. All the best for your SIP...6 weeks more yeah!