Screening and detection of IgG antibodies against severe fever with thrombocytopenia syndrome virus among blood donors in southwestern part of Japan.

INTRODUCTION

Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne infectious disease caused by SFTS virus (SFTSV). No large-scale evaluation of the seroprevalence of SFTSV infection in the general population of Kyushu-Okinawa, where it is endemic, had ever been conducted. This study aimed to detect the antibody for SFTSV in blood donors and estimate the prevalence of anti-SFTSV IgG antibodies in Kyushu-Okinawa.

MATERIALS AND

METHODS

Serum samples derived from 9987 blood donations were collected from December 2020 to January 2023. Anti-SFTSV antibodies was examined using the luciferase immunoprecipitation system (LIPS) with a recombinant nucleocapsid protein (rNP). LIPS-positive samples were further tested using indirect immunofluorescence assay (IFA) with rNP-expressed cells and enzyme-linked immunosorbent assay (ELISA) with SFTSV-infected cell lysate.

RESULTS

Forty-three (0.43 %) cases showed positive results in LIPS, with relative luminescence units ratios of 1.02-1.82. Three of these cases were regarded IFA-positive, although two of above three showed weak fluorescence reactions with 1:40 serum dilution. One of the two samples with weak-positive IFA results were reactive to both of SFTSV infected and -uninfected cell lysate in ELISA. Therefore, 2 of 9987 samples were confirmed to be with anti-SFTSV IgG antibodies.

CONCLUSIONS

In our study, anti-SFTSV-IgG antibodies was detected in 0.02 % of Kyushu-Okinawa blood donors. The antibody assay using SFTSV rNP antigen can be adopted in general laboratories, thus facilitating expanded seroprevalence surveillance. Increasing awareness and popularizing testing would help correct diagnosis of SFTSV infection and provide precise epidemiological data.