Int.J.Curr.Microbiol.App.Sci (2017) 6(12): 1586-1596 1586 Original Research Article https://doi.org/10.20546/ijcmas.2017.612.178 A Study on NS1 Antigen Detection ELISA Assay in Comparison with RNA Detection by Reverse Transcription Polymerase Chain Reaction for the Early Diagnosis of Dengue G. Sushma Rajya Lakshmi 1* , K. Nagamani 1 , K. Naga Soujanyai 1 , Manisha Rani 1 , Sunitha Pakalapaty 1 and Swathi Akula 2 1 Department of Microbiology, Gandhi Medical College, Secunderabad, Telangana India 2 Department of Microbiology, Kamineni Institute of Medical Sciences, LB Nagar, Telangana, India *Corresponding author ABSTRACT Introduction Dengue fever (DF) is the fastest emerging arboviral infection spread by Aedes aegypti mosquitoes with major public health consequences for millions of people around the world, and in particular the South-East Asia and Asia-Pacific Regions of the World Health Organization. The ecological disruption that occurred in the Southeast Asia and Pacific Regions during and following World War II, created ideal conditions for International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 6 Number 12 (2017) pp. 1586-1596 Journal homepage: http://www.ijcmas.com Diagnosis of dengue infection in acute phase is important for clinical care, implementing control measures, surveillance and research. Currently, dengue fever is diagnosed by means of virus isolation, reverse transcriptase PCR or IgM and IgG based ELISA. Given the limitations of all the existing diagnostic methods, there is a need for rapid, sensitive and high throughput methods for detection of dengue virus in early stages of the disease. The study was conducted with the objectives to evaluate a dengue virus NS1 antigen detection ELISA and a TaqMan based real time RT-PCR for detection of all four serotypes of dengue virus, as diagnostic tools for acute dengue virus infection. Out of 330 samples, NS1 antigen was positive in 75 cases (22.7%), IgM ELISA positive in 118 cases (35.7%) and IgG was positive in 281 cases (85.1%). Though the percentage of IgG positive samples was high, they were not considered due to their persistence lifelong and also as paired sera was not collected from the patients for confirmation of Dengue infection. Among 119 cases (group C), in 71 NS1 Ag positive cases, RT PCR positivity was 39.4%. In 103 IgM positive cases, RT PCR positivity was 20.38 %. Thus sensitivity of NS1 Ag was 97.26 % and sensitivity of multiplex RT PCR was 40.27 %, while specificity for both was 100 %. Concordance between NS1 antigen detection by ELISA and Multiplex RT- PCR was found to be 63.02 %. Both NS1 antigen detection and RNA detection was highest on day 3 of illness.NS1 antigen was detected from day 2 to day 10 of illness while RT-PCR was detected from day 2 to day 8 of illness. Concordance between NS1 antigen detection by ELISA and Multiplex RT-PCR was found to be 63.02 %. NS1 antigen detection ELISA and real time RT-PCR were found to be rapid, convenient and efficient tests for diagnosing of dengue fever in acute phase and the diagnosis could be made as early as within three days of onset of fever. Keywords ELISA, Polymerase chain reaction, Acute phase. Accepted: 12 October 2017 Available Online: 10 December 2017 Article Info