Brucellosis 2003 proceedings - PHIDIAS

Poster Session
weeks after infection whereas 16M-per-R was always in lower numbers. Although
less markedly, the difference between H38-per-R and 16M-per-R was also observed
at 10 7 and 10 8 CFU/mouse doses. At later times, the splenic CFU numbers
decreased gradually for both mutants, faster in the mice inoculated with the higher
doses (10 7 or 10 8 CFU) of the more virulent mutant (H38-per-R mutant), suggesting
that initial splenic levels and persistence were conversely related. When tested as
vaccines in the mouse model against B. melitensis, both mutants conferred
protection similar to that afforded by smooth Rev 1. At 10 7 CFU/mouse, H38-per-R
improved (P=0.027) the protection conferred by 16M-per-R, suggesting that H38-per-
R and 16M-per-R differ in vaccine properties.
89- COMPARISON OF Brucella melitensis R MUTANTS WITH INTACT OR
DEFECTIVE LIPOPOLYSACCHARIDE CORE AS VACCINES IN BALB/c MICE.
D. González, 1 M. J. Grilló, 2 P. M. Muñoz, 2 M. J. de Miguel, 2 D. Monreal, 1 C. M. Marín, 2 I. López-
Goñi, 1 I. Moriyón 1 and J. M. Blasco 2 . (1) Departamento de Microbiología, Universidad de Navarra,
Pamplona, Spain. (2) Unidad de Sanidad Animal, Servicio de Investigación Agroalimentaria, Gobierno
de Aragón, Zaragoza, Spain.
The attenuation and vaccine properties of B. abortus rough mutants in mice
depend on the extent of their lipopolysaccharide (LPS) core defects (Monreal et al.
2003. Infect. Immun. 71:3261-3271). To test whether this also occurs in B.
melitensis, mutants in the O-polysaccharide wbkD and core manB core genes were
obtained from the virulent smooth strain H38. Consistent with the predicted gene
role, the wbkD and manB core mutants bore an intact and a markedly deficient LPS
core, respectively. Studies in mice proved that: i), both mutants were attenuated as
compared to H38; ii), inoculated at 10 8 to 10 5 CFU, mutant manB core did not multiply
in spleens and was cleared by week 6; iii), at 10 6 or 10 5 CFU, mutant wbkD multiplied
to reach a plateau between weeks 2 and 3 and splenic numbers close to those of
strain H38; iv), no splenic multiplication of mutant wbkD could be observed when
inoculated at 10 7 or 10 8 CFU, and the numbers declined faster than at 10 6 or 10 5
doses; and v), mutant wbkD persisted in spleens for more than 6 weeks. When
tested as vaccines against B. melitensis in mice under the conditions established for
rough and smooth vaccines (10 8 CFU intraperitoneally and 10 5 CFU subcutaneously,
respectively), mutant manB core failed, and mutant wbkD and the smooth vaccine Rev
1 protected (P