Figure 1. Results of virulence testing of BRBV in immunocompetent mice. A, B) B6 mice (n = 4) infected intraperitoneally with the indicated doses of BRBV (A) or DHOV (B) were monitored for weight (mean +SEM) and survival. Animals were euthanized if they lost >25% body weight or showed severe illness. C) For virus growth, B6 mice (n = 5) were infected intraperitoneally with 100 PFU of DHOV and 1,000 PFU of BRBV. After 4 days, liver, lung, and spleen were harvested and a plaque assay performed. Geometric means are shown; dotted line indicates detection limit. D) Serum samples from BRBV- or DHOV-infected mice were pooled at 14 dpi. Vero cells were mock-treated or infected (multiplicity of infection 0.25) with BRBV, DHOV, and THOV and Western blot analysis of lysates from infected cells performed with antiserum at the indicated dilutions. Molecular weight and identity of the viral antigens are indicated. BRBV, Bourbon virus; DHOV, Dhori virus; dpi, days postinfection; GP, glycoprotein; LI, liver; LU, lung; M, matrix protein; NP, nucleoprotein; SP, spleen; THOV, Thogotovirus; ∅, mock-treated (control).