Serological Diagnostic Assays for Detection of Ns1 Antigen, IGM and IGG Antbodies to Dengue Virus

Complications in managing the dengue virus infections include the lack of rapid diagnostic procedures and at the same time the symptoms of dengue infection are often confused with those of other diseases. Two commercial rapid serological diagnostic kit methods (Dengue Day 1 test, J Mitra and Co. Pvt. Ltd., New Delhi, ImmunoComb II Dengue IgM/IgGBispot kit (Orgenics Pvt. Ltd., Israel)were evaluated for the detection of NS1 antigen, Immunoglobulin IgG and IgM specific to dengue virus in the serum samples of patients suffered with dengue acute primary infection and secondary infection. The total assay time was 20 min-2hrs. The results of these methods were compared with the gold standard assay methods Dengue IgM-Capture Microplate ELISA and Dengue Indirect IgG ELISA (Pan Bio, Brisbane, Australia). The total assay time was 6-7hrs. Nine serum samples were positive to NS1 antigen and negative to IgG and IgM by Dengue day 1 test. The results of Bispot assay method revealed that, the number of IgG positive samples was 11, IgM positive samples were 31 and both IgG and IgM positive samples were 8. Majority of the positive cases were noticed in the age group 35-68 years and males were more prone to dengue infection while comparing with females. By performing IgM MICROLISA, 34 samples were positive which in turn indicated that, three of them were false negative by the immune comb bispot method giving a sensitivity of 91.17%. Through indirect IgG ELISA, the number of positive samples was 15 and four of the 15 positive samples of IgG were false negative by the immuo comb bispot method giving a sensitivity of 73.33%. The gold standard ELISA methods were more efficient than rapid serological tests and gave an overall sensitivity of 99%. Thus the alternative of an assay that is to be used in the diagnosis of dengue infections depends on factors like laboratory infrastructure, preference and availability of equipment. The allied performance of the Rapid test, followed by confirmation with MAC-ELISA on those samples, ensures both speediness as well as quality of reported results.