Expression and Immunogenic Application of Recombinant DENV-2 rprM Protein for the Non-Invasive Detection of Salivary IgA Antibodies

Dengue virus (DENV) serotypes 1–4 cause dengue, a major re-emerging disease in tropical and subtropical regions. This study evaluated the antigenicity of a recombinant DENV-2 premembrane protein (rprM-DENV-2) and its ability to detect anti-DENV human IgA antibodies. The rprM-DENV-2 protein was expressed in Escherichia coli, purified, and assessed for immunogenicity and antigenicity. The recombinant protein induced IgG antibodies in rats, which detected DENV infection in Vero cells. Importantly, in paired saliva and serum samples from patients diagnosed with dengue, IgA antibodies were detected by ELISA using the rprM-DENV-2 antigen, but not in samples from the negative control group (subjects residing in a non-endemic area), with a significant difference (p < 0.0001). These findings demonstrate that rprM-DENV-2 retains antigenic properties similar to the native viral protein; this may be useful for in vitro studies of DENV infection and IgA detection in non-invasive clinical samples.