A Study Of Sero-prevalence And Rates Of Asymptomatic Viremia Of Severe Fever With Thrombocytopenia Syndrome Virus (SFTSV) Among Chinese Blood Donors

Objective:Severe fever with thrombocytopenia syndrome virus(SFTSV), is a novel phlebovirus which was first identified in patients with fatal severe fever with thrombocytopenia syndrome (SFTS) in 2009 in China. It was reported that this virus can be transmitted through blood contact. Therefore, this study aims to investigate the seroprevalence and viremic rates of SFTSV in healthy Chinese blood donors in Xinyang, the endemic region, and in Luoyang and Mianyang non-epidemic regions.Methodsk:A specific and sensitive in-house reverse transcription (RT) and Real-time-PCR assay was established based on the Taqman probe method. A total of 17208 plasma samples were collected from April 16 to Oct 31,2012. Most of the samples (14752 out of 17208) were collected from Xinyang, which is located in the SFTSV endemic region, and all the other samples (7248 out of 17208) were obtained from Luoyang and Mianyang blood centres where no epidemic of SFTSV was reported. SFTSV RNA from 2490 pools (1 pool consists of 4 donor samples,9960 samples totally) from Xinyang blood centre were tested using the in-house PCR assay. And the reactive pools were further tested in the form of individual blood sample. All the samples from three blood centres were tested by Enzyme Linked Immunoassay (ELISA) to obtain the status of SFTSV total antibodies (IgG and IgM). The repeat reactive samples of ELISA were tested for the SFTSV RNA by the PCR method described above. The demographic characteristics of ELISA reactive donors were further analyzed after these experiments.Results:63 out of 2490 pools of Xinyang samples were initially reactive for SFTSV RNA, among which only 2 reactive samples were identified by individual sample RT-PCR. The 2 reactive samples have viral load lower than lOpfu/mL and the amplification cycle number (Cqs) were 39.7 and 39.3 respectively. Based on this screening, SFTSV RNA prevalence among Chinese healthy donors was 0.02%(2/9960) in Xinyang endemic region. Simultaneously, the sero-prevalence of blood donors from Xinyang blood centre was 0.54% (80/14752), and the rates of total antibody in Luoyang and Minyang were 0.23%(3/1326) and 0.27%(3/1130), respectively. Interestingly, all the sero-positive samples were negative in the SFTSV RNA testing. No significant correlation between sero-positive status and demographic characteristics was identified among blood donors from three Chinese blood centres.Conclusions:The prevalence of SFTSV total antibody in healthy donors from three regions ranges from 0.27% to 0.59%, however, none of them was RNA positive. And the SFTSV RNA prevalence was 0.02% in Xinyang endemic region. The relatively low prevalence of total antibody and RNA among donors suggests limited impact of SFTSV on blood safety in these three regions.To our knowledge, up till now our current study consists of the largest study population from multiple regions, both from endemic and non-endemic, in order to assess the potential threat of the transmission of SFTSV through transfusion among the healthy Chinese blood donors.