Clinical signs and gross findings.

Humanized mice (hu-BLT, hu-CD34+ and hu-PBMC) were inoculated via the intranasal route with 7x103 or 7x105 plaque forming units (pfu) of VARV (VARV_JAP51_hrpr (primary clade I)) (n = 4 per group). Clinical signs were recorded daily, and weights were taken at least three times weekly. Euthanasia/pain scores were determined by weight loss, behavior and appearance. We only considered a score of ≥5 as clinical signs attributed to viral infection because a score of 4 was often seen in non-infected controls due to weight loss alone; weight loss was not utilized as a pain score for control mice unless observed for two consecutive weight recording days. At 21 days post infection (dpi) or a pain score of 10, euthanasia was performed and gross findings during necropsy recorded. Clinical signs, mortality, and abnormal gross findings are displayed per group. Hu-CD34+-8 was excluded from this analysis since it was unsuccessfully infected.