An anti-Gn glycoprotein antibody from a convalescent patient potently inhibits the infection of severe fever with thrombocytopenia syndrome virus

Ki Hyun Kim; Jinhee Kim; Meehyun Ko; June Young Chun; Hyori Kim; Seungtaek Kim; Ji-Young Min; Wan Beom Park; Myoung-don Oh; Junho Chung

Type I interferon (interferon α/β) receptor gene (IFNAR1) deficient A129 mice (n = 5 144 per group) were subcutaneously injected with the Gangwon/Korea/2012 strain of SFTSV at a 145 dose of either 2 or 20 plaque forming units (PFU). After 1 h, mice were intraperitoneally 146 administered with either phosphate-buffered saline (PBS), Ab10, MAb4-5, or a human IgG 1 147 isotope control antibody at a dose of 600 μg (approximately corresponding to 30 mg/kg of 148 body weight); for 4 days at 24 h intervals, the injection of the same amount of antibody was 149 performed (Fig 2A) . 176 ranging from 10 pM to 1 nM ( Fig 4A) . Further, the amount of antibody bound to the HB29 177 and SD4 Gn glycoproteins coated on the ELISA plate was higher than that of the 178 Gangwon/Korea/2012 glycoproteins, at most of the tested concentrations. We also found that 179 Mab4-5 was reactive to Gn glycoprotein from the HB29 and SD4 strains ( Fig 4B) . 180 We used surface plasmon resonance analysis to determine the kinetics of Ab10 181 binding to the Gn glycoprotein of Gangwon/Korea/2012. Ab10 bound to Gn glycoprotein 182 with an equilibrium dissociation constant (K D ) of 104 pM and found an association rate (K on ) 183 of 7.4  10 5 M -1 s -1 and a dissociation rate (K off ) of 7.7  10 -5 s -1 (Fig 4C) .