Experimental and Natural Infections of Goats with Severe Fever with Thrombocytopenia Syndrome Virus: Evidence for Ticks as Viral Vector.

Yongjun Jiao,Xian Qi,Yewu Han,Xiling Guo,Xiaoyan Zeng,Dapeng Liu,Hua Wang,Minghao Zhou,Zhiyang Shi,Rosemary C Sang

doi:10.1371/journal.pntd.0004092

Abstract

BackgroundSevere fever with thrombocytopenia syndrome virus (SFTSV), the causative agent for the fatal life-threatening infectious disease, severe fever with thrombocytopenia syndrome (SFTS), was first identified in the central and eastern regions of China. Although the viral RNA was detected in free-living and parasitic ticks, the vector for SFTSV remains unsettled.Methodology/Principal FindingsFirstly, an experimental infection study in goats was conducted in a bio-safety level-2 (BSL-2) facility to investigate virus transmission between animals. The results showed that infected animals did not shed virus to the outside through respiratory or digestive tract route, and the control animals did not get infected. Then, a natural infection study was carried out in the SFTSV endemic region. A cohort of naïve goats was used as sentinel animals in the study site. A variety of daily samples including goat sera, ticks and mosquitoes were collected for viral RNA and antibody (from serum only) detection, and virus isolation. We detected viral RNA from free-living and parasitic ticks rather than mosquitoes, and from goats after ticks’ infestation. We also observed sero-conversion in all members of the animal cohort subsequently. The S segment sequences of the two recovered viral isolates from one infected goat and its parasitic ticks showed a 100% homology at the nucleic acid level.Conclusions/SignificanceIn our natural infection study, close contact between goats does not appear to transmit SFTSV, however, the naïve animals were infected after ticks’ infestation and two viral isolates derived from an infected goat and its parasitic ticks shared 100% of sequence identity. These data demonstrate that the etiologic agent for goat cohort’s natural infection comes from environmental factors. Of these, ticks, especially the predominant species Haemaphysalis longicornis, probably act as vector for this pathogen. The findings in this study may help local health authorities formulate and focus preventive measures to contain this infection.

Highlights

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by severe fever with thrombocytopenia syndrome (SFTS) bunyavirus (SFTSV) [1]
Severe fever with thrombocytopenia syndrome virus (SFTSV), a newly identified bunyavirus, has been found to circulate in mainland China, South Korea, and Japan since 2009. This virus is the etiologic agent for an emerging fatal hemorrhagic fever, severe fever with thrombocytopenia syndrome (SFTS) with high fatality
In the experimental infection study, we have not found any viral transmission within the cohort by close contact between animals

Summary

Introduction

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by SFTS bunyavirus (SFTSV) [1]. This virus was originally identified in 6 provinces of central and northeastern China [1]. Severe fever with thrombocytopenia syndrome virus (SFTSV), the causative agent for the fatal life-threatening infectious disease, severe fever with thrombocytopenia syndrome (SFTS), was first identified in the central and eastern regions of China. The viral RNA was detected in free-living and parasitic ticks, the vector for SFTSV remains unsettled

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Results

Discussion

Conclusion