Evaluation of NS1-Detection-Based Cell Culture Method for Isolation of Dengue Viruses from Clinical Samples

Abstract

Dengue is the fastest spreading mosquito-borne viral infection across the globe affecting over 40% of world populations. Co-existence of 4 distinct serotypes, disease severity due to secondary infection, and continuous evolution of dengue viruses over the years intensify the need for a better and effective virus surveillance program. In this study, we evaluated NS1 antigen detection method to screen large number of clinical samples for dengue virus isolation. Patient’s serum samples were added onto in vitro tissue culture grown C6/36 or Vero cell lines. Seven days post-infections, culture supernatants were harvested for testing of NS1 antigen by ELISA to confirm the presence of dengue viruses. Significantly higher rate of virus isolation was observed in Vero cells at 7 days post-infection in comparison to C6/36 cells. NS1 antigen could be detected earliest at day 3 post-infection in culture supernatants of both C6/36 and Vero cells. Use of Vero cells in a single 35-mm culture dishes resulted in 69.7% DENV isolations from NS1 alone positive samples. The method is economical, easy to perform, and useful in handling large number of clinical samples and will be of value in virus surveillance, especially post-vaccination.