29Burkholderia pseudomallei causes melioidosis, a common source of pneumonia and sepsis in 30 Southeast Asia and Northern Australia, that results in high mortality rates. A caprine melioidosis 31 model of aerosol infection that leads to a systemic infection has the potential to characterize the 32 humoral immune response. This could help identify immunogenic proteins for new diagnostics 33 and vaccine candidates. Outbred goats may more accurately mimic human infection, in contrast to 34 the inbred mouse models used to date. B. pseudomallei infection was delivered as an intratracheal 35 aerosol. Antigenic protein profiling was generated from the infecting strain MSHR511. Humoral 36 immune responses were analyzed by ELISA and western blot, and the antigenic proteins were 37 identified by mass spectrometry. Throughout the course of the infection the assay results 38 demonstrated a much greater humoral response with IgG antibodies, in both breadth and quantity, 39 compared to IgM antibodies. Pre-infection sera showed multiple immunogenic proteins already 40 reactive for IgG (7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) and IgM (0-12) in most of the goats despite no previous exposure to B. 41 pseudomallei. After infection, the number of IgG reactive proteins showed a marked increase as 42 the disease progressed. Early stage infection (day 7) showed immune reaction to chaperone 43 proteins (GroEL, EF-Tu, and DnaK). These three proteins were detected in all serum samples after 3 44 infection, with GroEL immunogenically dominant. Seven common reactive antigens were selected 45 for further analysis using ELISA. The heat shock protein GroEL1 elicited the strongest goat 46 antibody immune response compared to the other six antigens. Most of the six antigens showed 47 the peak IgM reactivity at day 14, whereas the IgG reactivity increased further as the disease 48 progressed. An overall MSHR511 proteomic comparison between the goat model and human sera 49 showed that many immune reactive proteins are common between humans and goats with 50 melioidosis. 51 52 Author Summary 53 B. pseudomallei infection, the causative agent of melioidosis, results in severe 54 disseminated or localized infections. A systemic study of the humoral immune response to B. 55 pseudomallei infection using the B. pseudomallei aerosol caprine model would help understand 56 the detectable antigenic proteins as the infection progresses. To study the immune response, IgG 57 and IgM antibody responses to whole cell lysate proteins were identified and analyzed. Antigenic 58 carbohydrates were also studied. From the results, this study suggests that the caprine humoral 59 immune response to aerosolized B. pseudomallei has similarities to human melioidosis and may 60 facilitate the analysis of the temporal antibody responses. In addition, commonly detected 61 immunogenic proteins may be used as biomarkers for the future point of care (POC) diagnostics.62 4 63 Introduction 64 Burkholderia pseudomallei is a Gram-negative, non-spore formin...