Development of a reverse transcription polymerase chain reaction for the detection of severe fever with thrombocytopenia syndrome virus from suspected infected animals

Abstract Background Severe fever with thrombocytopenia syndrome virus (SFTSV) causes severe hemorrhagic fever in humans and cats. Clinical symptoms of SFTS-infected cats resemble to those of SFTS patients and SFTS-contracted cats shows high levels of viral RNA loads in the serum and body fluids. Due to the risk of direct infection from SFTS-infected cats to human, it is important to diagnose SFTS-suspected animals. Methodology/Principle findings Four primer sets were newly designed from consensus sequences constructed by 108 strains of SFTSV. A reverse transcription polymerase chain reaction (RT-PCR) with these four primer sets were successfully and specifically detected several clades of SFTSV. Their limits of detection are 1-10 copies/reaction. By this RT-PCR, 5 cat cases among 56 SFTS-suspected animal cases were diagnosed as SFTS. From these cats, IgM or IgG against SFTSV were detected by enzyme-linked immunosorbent assay (ELISA), but not neutralizing antibodies by plaque reduction neutralization titer (PRNT) test. This phenomenon is similar to those of fatal SFTS patients. Conclusion/Significance This newly developed RT-PCR could detect SFTSV RNA of several clades from SFTS-suspected animals. In addition to ELISA and PRNT test, the useful laboratory diagnosis systems of SFTS-suspected animals has been made in this study. Author summary This study developed RT-PCR to detect SFTS animal cases. This assay could detect SFTSV RNA belonging to different clades. Cats diagnosed as SFTS had IgM or IgG, but not neutralizing antibodies. SFTS cat cases were distributed in the area where SFTS patients have been reported highly, indicating the establishment of the circulation of SFTSV in the environment. These diagnostic assays could be helpful tools to detect and not to miss SFTS animal cases.