Fig. 1: OMV-vaccination prevents severe disease in rhesus macaques.

a NHPs were given two doses of OMV vaccine or sham 4 weeks apart, then challenged with B. pseudomallei. b Seventy-five percent (3/4) of NHPs immunized with OMV (blue triangles) vaccine survived to the day 21 study endpoint, whereas only 33% (2/6) of sham-immunized NHPs (black circles) survived, p = 0.24 as determined by the Log Rank Mantel-Cox test. One animal in the OMV group (KM49) was removed from the study and right censored at day 14 due to an unrelated event. c Febrile response of OMV- (animal ID KP07, top) and sham-immunized (KV38, bottom) macaques post-challenge. Fever (red boxes) or hypothermia (blue boxes) were defined as a 1.5-degree in core temperature increase or decrease, respectively, from the normal diurnal pattern of the macaque (green boxes). Each animal served as its own control using data collected prior to challenge (black boxes, error bars represent the range of temperatures collected by the telemetry device during the one minute sampling time interval), with post-exposure biotelemetry data plotted as an overlay, with a single temperature measurement taken at each time point for each animal. One animal is shown per group. d Gross pathology images performed at necropsy demonstrating normal appearing lungs for OMV vaccinated survivors (4 total) versus multifocal pneumonia for sham-immunized survivors (2 total). All animals that succumbed (1 OMV, 4 sham) early to infection displayed necrotizing, hemorrhagic pneumonia. e Representative images of lung histopathology demonstrating absence of alveolar inflammation (KP07), organized areas of alveolar congestion (KV38), granuloma formation (KJ33), and significant alveolar inflammation with granuloma formation (KP86). Scale bar = 1000 μm. f Histopathologic scoring performed on lungs at necropsy. Closed blue triangles -OMV-immunized, survived; open blue triangles – OMV-immunized, died, closed black circles -sham-immunized, survived, open black circles – sham-immunized, died. Four slides were analyzed per lung and scored 0–5 (OMV-immunized n = 5, sham-immunized n = 6). Non-parametric distribution was assumed, and statistical analysis was determined using the one-tailed Mann-Whitney test. g Representative images of histopathology performed on OMV-immunized animal KP07 demonstrating iBALT formation. Left, scale bar = 1000 μm, right, scale bar = 200 μm.