Optimized Sindbis Virus RNA Detection Using Novel RT-qPCR: Isolation and Characterization of Sindbis Virus from a Patient Sample

<b><i>Background:</i></b> Strains of Sindbis virus (SINV) are rarely detected and isolated from human blood samples as the viremia is low and short in Pogosta disease patients. <b><i>Materials and Methods:</i></b> To optimize SINV RNA detection in patient samples, a sensitive and specific SINV-RT-qPCR method was developed and validated. <b><i>Results:</i></b> The new SINV-RT-qPCR method was determined to be more sensitive than a previously used method. The assay was used to screen 882 serum samples from 846 patients suspected of Pogosta disease in Finland in 2023-2024. One sample was detected to be SINV-RNA-positive and was further subjected to virus isolation with whole genome sequencing. The sequence analysis suggested the strain to be closely related to those detected in Finland in 2005 and 2018, Germany in 2012 and 2016, and Sweden in 2009. <b><i>Conclusions:</i></b> The new optimized SINV RNA detection method is a useful tool for the detection of viremic samples for further studies.