Submitted to: American Society for Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 20, 2001
Publication Date: N/A
Technical Abstract: A rapid increase in the population of Mannheimia haemolytica (MH) in the nasopharynx is a prerequisite for development of acute MH pneumonia in transported cattle. The selective growth has been inhibited by sub- cutaneous vaccination with an experimental bacterin grown in a manner that would induce iron-regulated outer membrane protein (IROMP) production. .IROMPs would assist bacteria in colonizing the nasopharynx, and antibody t IROMPs may be an important colonization-inhibiting factor. Pre-transport serums of vaccinated and non-vaccinated cattle were assayed for antibody to MH IROMP by an ELISA procedure that utilized as antigen a complex of five proteins (MW approximately 101, 82, 77, 45, and 16 kDa). The proteins were isolated from the OMP of MH grown in iron-depleted medium by affinity chromato-graphy, using Sepharose-bound bovine holotransferrin. The proteins were characterized by SDS-PAGE, immunoblotting, reaction with holo-transferrin, and 2-D electrophoresis. Parameters for an ELISA procedure were established. ELISA titers were compared with vaccination and with MH isolation from the nasopharynx after transport. ELISA titers against IROMPs were significantly greater in vaccinated cattle regardless of colonization status. We have developed as ELISA procedure to measure serum antibody to MH IROMPs. The procedure can be used to help determine the role of antibody to IROMPs in inhibition of colonization.