The Application of RNAscope Protocol to Detect Dengue Virus in Human Paraffin-Embedded Tissue

Dengue is an important arthropod-borne viral disease, endemic in over 100 countries and challenging health care systems worldwide São Paulo, Brasil. The disease can be clinically diagnosed by the detection of dengue-specific antibodies, nonstructural 1 antigen, or viral RNA by reverse transcriptase-polymerase chain reaction São Paulo, Brasil. When there is an indication to perform a biopsy or in cases of retrospective studies using material from necropsy, immunohistochemistry is an efficient tool. Recently, RNAscope has emerged as a new generation of in situ hybridization technique, with the advantage of different probes, including a probe to Dengue virus. This paper aimed to analyze the use of the RNAscope technique as a supplementary method, compared to immunohistochemistry, for the evaluation of dengue virus in human specimens. An immunohistochemical and molecular study was conducted in pulmonary and renal tissues from individuals who died due to severe dengue, selected according to clinical and serological diagnosis. The immunohistochemical assay was performed using a monoclonal anti-dengue virus antibody. Positivity was visualized in the cytoplasm of mononuclear cells in the interalveolar septal region and also in glomeruli and tubules. RNAscope was performed using a probe to dengue type 2. It was possible to visualize the positivity as small dots or clusters in the same area in the lungs and tubules in the kidney specimen. The finding of dots or clusters through the RNAscope protocol could suggest viral replication; however, only the finding of replicative intermediates or cultures would confirm such activity.