SRA

Severe fever with thrombocytopenia syndrome phlebovirus (SFTSV), listed in the WHO most dangerous pathogens, has 12-30% fatality rates with a characteristic thrombocytopenia syndrome. With a majority of clinically diagnosed SFTSV patients older than ~50 years, age is a critical risk factor for SFTSV morbidity and mortality. Here, we report an age-dependent ferret model of SFTSV infection and pathogenesis that fully recapitulates the clinical manifestations of human infections. While young adult ferrets (=2 years old) did not show any clinical symptoms and mortality, SFTSV-infected aged ferrets (=4 years old) demonstrated severe thrombocytopenia, reduced white blood cells, and high fever with 93% mortality rate. Moreover, significantly higher viral load was observed in aged ferrets. Transcriptome analysis of SFTSV-infected young ferrets revealed strong interferon-mediated anti-viral signaling, whereas inflammatory immune responses were markedly upregulated and persisted in aged ferrets. Thus, this immunocompetent age-dependent ferret model should be useful for anti-SFTSV therapy and vaccine development. Overall design: Two groups of young adults (20-24 months, =2Y) and aged ferrets (48-50 months), =4 Y) were inoculated via the IM route with 107.6 TCID50 of the SFTSV CB1/2014 strain. PBMCs were isolated at 2 and 4 dpi from each group of ferrets (n=3) by density gradient centrifugation using Ficoll-Paque Plus according to the manufacture's protocol.