title: Current understanding of the equine immune response to Rhodococcus equi. An immunological review of R. equi pneumonia.
abstract: Rhodococcus equi is recognised to cause chronic purulent bronchopneumonia in foals of less than 6 months of age. Virulent strains of the bacteria possess a large 80-90 kb plasmid encoding several virulence-associated proteins, including virulence-associated protein A (VapA), which is associated with disease. R. equi pneumonia can represent significant costs and wastage to the equine breeding industry, especially on stud farms where the disease is endemic. This article reviews knowledge of the equine immune response, both in the immune adult and susceptible neonate, with respect to this pathogen. Humoral immune responses are addressed, with a discussion on the use of hyperimmune and normal adult equine plasma as prophylactic tools. The role that innate immune mechanisms play in the susceptibility of some foals to R. equi infection is also highlighted. Likewise, cell-mediated immune components are reviewed, with particular attention directed towards research undertaken to develop an effective vaccine for foals. It is possible that the implementation of a single immunoprophylaxis strategy to prevent R. equi infection on farms will yield disappointing results. Combined prophylactic protocols that address husbandry practices, environmental and aerosol contamination levels, enhancement of innate immunity, good quality hyperimmune plasma for the neonate, and vaccinal efficacy in the developing foal may be required.
authors.affiliation: The Faculty of Applied Sciences, University of Sunderland, Fleming Building, Wharncliffe Street, Sunderland SR1 3SD, UK. Electronic address: hc4tda@student.sunderland.ac.uk.
authors.forename: Tamsin R M Y
authors.initials: TRMY
authors.lastname: Dawson
authors.affiliation: Department of Veterinary Science, University of Kentucky, UK.
authors.forename: David W
authors.initials: DW
authors.lastname: Horohov
authors.affiliation: School of Biomolecular and Biomedical Science, University College Dublin, Ireland.
authors.forename: Wim G
authors.initials: WG
authors.lastname: Meijer
authors.affiliation: Faculty of Veterinary Science, The University of Sydney, Australia.
authors.forename: Gary
authors.initials: G
authors.lastname: Muscatello
mesh_terms: D000193:Actinomycetales Infections / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D000818:Animals; D000831:Animals, Newborn / Q000276:immunology / Q000382:microbiology; D001428:Bacterial Vaccines / Q000276:immunology; D006734:Horse Diseases / Q000276:immunology* / Q000382:microbiology / Q000517:prevention & control; D006736:Horses / Q000276:immunology; D056724:Immunity, Humoral / Q000276:immunology; D007113:Immunity, Innate / Q000276:immunology; D018410:Pneumonia, Bacterial / Q000276:immunology / Q000662:veterinary*; D016929:Rhodococcus equi / Q000276:immunology*
chemical_list: D001428:Bacterial Vaccines