Burkholderia pseudomallei causes
melioidosis, a common source of
pneumonia and
sepsis in Southeast Asia and Northern Australia that results in high mortality rates. A caprine
melioidosis model of
aerosol infection that leads to a systemic
infection has the potential to characterize the humoral immune response. This could help identify immunogenic
proteins for new diagnostics and
vaccine candidates. Outbred goats may more accurately mimic human
infection, in contrast to the inbred mouse models used to date. B. pseudomallei
infection was delivered as an intratracheal
aerosol. Antigenic
protein profiling was generated from the infecting strain MSHR511. Humoral immune responses were analyzed by ELISA and western blot, and the antigenic
proteins were identified by mass spectrometry. Throughout the course of the
infection the assay results demonstrated a much greater humoral response with
IgG antibodies, in both breadth and quantity, compared to
IgM antibodies. Pre-
infection sera showed multiple immunogenic
proteins already reactive for
IgG (7-20) and
IgM (0-12) in most of the goats despite no previous exposure to B. pseudomallei. After
infection, the number of
IgG reactive
proteins showed a marked increase as the disease progressed. Early stage
infection (day 7) showed immune reaction to chaperone
proteins (GroEL,
EF-Tu, and DnaK). These three
proteins were detected in all serum samples after
infection, with GroEL immunogenically dominant. Seven common reactive
antigens were selected for further analysis using ELISA. The
heat shock protein GroEL1 elicited the strongest goat antibody immune response compared to the other six
antigens. Most of the six
antigens showed the peak
IgM reactivity at day 14, whereas the
IgG reactivity increased further as the disease progressed. An overall MSHR511 proteomic comparison between the goat model and human sera showed that many immune reactive
proteins are common between humans and goats with
melioidosis.