Rough mutants defective in core and O-polysaccharide synthesis and export induce antibodies reacting in an indirect ELISA with smooth lipopolysaccharide and are less effective than Rev 1 vaccine against Brucella melitensis infection of sheep.
Classical brucellosis vaccines induce antibodies to the O-polysaccharide section of the lipopolysaccharide that interfere in serodiagnosis. Brucella rough (R) mutants lack the O-polysaccharide but their usefulness as vaccines is controversial. Here, Brucella melitensis R mutants in all main lipopolysaccharide biosynthetic pathways were evaluated in sheep in comparison with the reference B. melitensis Rev 1 vaccine. In a first experiment, these mutants were tested for ability to induce anti-O-polysaccharide antibodies, persistence and spread through target organs, and innocuousness. Using the data obtained and those of genetic studies, three candidates were selected and tested for efficacy as vaccines against a challenge infecting 100% of unvaccinated ewes. Protection by R vaccines was 54% or less whereas Rev 1 afforded 100% protection. One-third of R mutant vaccinated ewes became positive in an enzyme-linked immunosorbent assay with smooth lipopolysaccharide due to the core epitopes remaining in the mutated lipopolysaccharide. We conclude that R vaccines interfere in lipopolysaccharide immunosorbent assays and are less effective than Rev 1 against B. melitensis infection of sheep.
Barrio
María B
MB
INRA, UR1282, Infectiologie Animale et Santé Publique, IASP, Nouzilly F-37380, France.
Grilló
María J
MJ
Muñoz
Pilar M
PM
Jacques
Isabelle
I
González
David
D
de Miguel
María J
MJ
Marín
Clara M
CM
Barberán
Montserrat
M
Letesson
Jean-J
JJ
Gorvel
Jean-P
JP
Moriyón
Ignacio
I
Blasco
José M
JM
Zygmunt
Michel S
MS
D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis*; D001428:Bacterial Vaccines / Q000276:immunology*; D017347:Brucella melitensis / Q000276:immunology*; D002006:Brucellosis / Q000276:immunology* / Q000662:veterinary*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005612:Freeze Drying; D008070:Lipopolysaccharides / Q000096:biosynthesis* / Q000235:genetics*; D008264:Macrophages / Q000382:microbiology; D008297:Male; D051379:Mice; D009154:Mutation / Q000276:immunology; D011247:Pregnancy; D012756:Sheep; D012757:Sheep Diseases / Q000276:immunology*; D014611:Vaccination
D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; D008070:Lipopolysaccharides