NS1 based protein assays could potentially pick up infections missed by prM-E based front-line serological tests.[20] Antibodies to envelope protein were detected in 91% of the DENV cases while NS1 antibodies were detected in 99%, indicating that NS1 has a higher sensitivity.[18] Two of the nine DENV IgM positive samples from travelers that tested negative on DENV IgG ELISA, which is based on the prM-E antigen, tested IgG positive on our microarray, further supporting this assumption. Here, ERVW-1 is linked to infection.