Safety and immunogenicity of a live-attenuated auxotrophic candidate vaccine against the intracellular pathogen Rhodococcus equi.
Rhodococcus equi causes serious pneumonia in neonatal foals and is an opportunistic pathogen of people with compromised cellular immunity. No effective vaccine against R. equi disease in foals is available. We tested the safety and immunogenicity of a live, fully attenuated riboflavin auxotrophic candidate vaccine strain of R. equi (R. equi rib-). We demonstrated that R. equi rib- is immunogenic and capable of inducing IFN-gamma responses in immunocompetent BALB/c mice, yet it is safe even in an immunocompromised SCID mouse infection model. Moreover, it protects immunocompetent mice against virulent R. equi challenge. In foals, R. equi rib- was likewise safe and stimulated serum R. equi-specific immune responses. A preliminary immunization strategy did not afford protection against virulent R. equi challenge and therefore, optimization of the vaccine formulation and or vaccination protocol will be necessary.
Lopez
A M
AM
Vaccine and Infectious Disease Organization, University of Saskatchewan, 120 Veterinary Road, Saskatoon, SK, S7N 5E3, Canada. marianela.lopez@usask.ca
Townsend
H G G
HG
Allen
A L
AL
Hondalus
M K
MK
D000193:Actinomycetales Infections / Q000382:microbiology / Q000473:pathology / Q000517:prevention & control / Q000662:veterinary*; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology; D005260:Female; D006734:Horse Diseases / Q000382:microbiology / Q000473:pathology / Q000517:prevention & control*; D006736:Horses; D007114:Immunization; D007121:Immunocompetence; D007371:Interferon-gamma / Q000096:biosynthesis; D008168:Lung / Q000382:microbiology / Q000473:pathology; D008213:Lymphocyte Activation; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D016929:Rhodococcus equi / Q000276:immunology* / Q000472:pathogenicity; D012256:Riboflavin; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology
D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; D014613:Vaccines, Attenuated; D007371:Interferon-gamma; D012256:Riboflavin