Brucellosis 2003 proceedings - PHIDIAS

Poster Session
melitensis wild type virulent strain 16M. Four weeks after inoculation, strain WRSPA
completely cleared from spleens. These results indicate that strain WRSPA is not as
virulent as strain 16M and not as attenuated as strain WRRP1. The recombinant
strains WR201PA and WRSPA have potential as vaccine candidates against anthrax
and brucellosis in humans.
92- EVALUATION OF B. abortus M1luc AND I2 AS VACCINES AGAINST BOVINE
BRUCELOSIS.
E. Campos 1 , S. Cravero 1 , A. Fiorentino 2 , A. Arese 1 , F. Paolicci 2 , C. Campero 2 , O. Rossetti 1 . (1) Inst.
de Biotecnología. CICVyA. Argentina. (2) EEA Balcarce. INTA. Buenos Aires. Argentina.
B. abortus M1luc is a mutant strain derived from S19 in which most of bp26
sequence has been replaced by the luc gene. I2 is a double mutant in which, apart
from bp26 mutation, most of omp19 has been deleted. In BALB/c mice, M1luc
behaved as S19. I2 was more attenuated than S19 but conferred the same level of
protection against challenge with S2308. The objective was to obtain strains that
could be easily distinguished from field strains (by use of the luc marker) and that
had an associated diagnostic test (using BP26 antigen). In I2, the objective was to
generate a strain that would also have less residual virulence than S19, retaining its
protection capacity. For evaluation in the natural host, groups of 5-month old heifers
were either not vaccinated or vaccinated with 2x10 10 CFU of S19, M1luc or I2 (N=15,
each). All vaccines generated equal humoral immune response against LPS. Animals
were inseminated and then challenged, in the third trimester of pregnancy, with
3x10 7 CFU of S2308. The protection levels against abortion were 78.6% for S19,
81.8% for M1luc and 45.5% for I2. From the non-vaccinated group, 25% did not
abort. These results indicate that Omp19 is necessary for S19 full protection
capacity. The BP26-i ELISA was highly specific for animals vaccinated with M1luc or
I2. S19 vaccinated animals developed anti-BP26 antibodies after 6 months of
vaccination. The control group did not present antibodies against BP26 at any time.
However, sensitivity after the experimental challenge was much lower than the one
obtained for naturally infected cattle.
93- EVALUATION OF NOVEL Brucella abortus AND Brucella melitensis
DELETION MUTANTS AS POTENTIAL VACCINE CANDIDATES IN THE MOUSE
AND GOAT MODELS OF BRUCELLOSIS.
M. Kahl 1 , P. H. Elzer 2 , S. D. Hagius 2 , D. S. Davis 1 , A. Den-Hartigh 3 , R. Tsolis 3 and T. A. Ficht 1 . (1)
Veterinary Pathobiology, Texas A&M University and Texas Agricultural Experiment Station, College
Station, TX 77843-4467. USA. (2) Department of Veterinary Science, LSU AgCenter, Baton Rouge,
LA. USA. (3) Microbiology and Immunology, Texas A&M Health Science Center, College Station, TX.
USA.
Using in vivo screening of signature tagged mutant banks, we have identified
several B. abortus genes that are attenuated in virulence due to a reduced ability to
either establish or maintain a successful infection in the mouse model. Based on the
ability of selected mutants to stimulate a protective immune response in the mouse,
we hypothesized that one or more deletion mutants may prove to be superior to
currently available vaccines in large animals. The creation of unmarked deletion
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Brucellosis 2003 International Research Conference