Brucellosis 2003 proceedings - PHIDIAS

Keynote Lectures
CLASSICAL AND NEW GENERATION VACCINES AGAINST BRUCELLOSIS IN
UNGULATES.
Philip H. Elzer. LSU AgCenter and School of Veterinary Medicine, Baton Rouge, LA, 70803. USA.
Worldwide there are five Brucella vaccines for use in animal populations: B.
abortus 45/20, B. melitensis Rev-1, B. suis strain 2, B. abortus strains 19, and RB51.
The killed vaccine strain 45/20 did not consistently protect against virulent challenge
and also caused some abortions. B. suis strain 2 has not be evaluated extensively
and can cause vaccinal titers. Rev-1 provides protection in sheep and goats against
brucellosis; however, it can cause abortions and titers. Strain 19 protects cattle
against brucellosis but may also cause abortions and titers; and it is not effective in
wildlife species, primarily bison and elk.
Currently B. abortus strain RB51 is the only vaccine that does not cause
vaccinal titers. RB51 appears to be safe in the majority of ungulates and non-target
species tested in that it does not cause abortion. RB51 does cause abortions in
pregnant reindeer, and it is not efficacious against virulent challenge in elk and bison.
With no vaccines to protect wildlife, primarily bison, elk and feral swine, it is
imperative that new vaccine candidates be evaluated.
New vaccine candidates for use in wildlife and domestic animals are being
evaluated. OMP25 gene deletion mutants in B. abortus, B. melitensis, and B. ovis
have been tested in cattle, goats and sheep and did not demonstrate any detrimental
effects. Vaccinal titers can be distinguished from field strain titers using these vaccine
strains. The B. melitensis mutant does not cause abortions and protects goats
against virulent challenge. VTRS-1 is a rough derivative of virulent B. suis, and
vaccination of swine with this strain does not cause vaccinal titers or abortion and
provides sows protection against virulent challenge.
ALTERNATIVE BRUCELLOSIS VACCINES: EXPERIENCES WITH DRUG
DELIVERY SYSTEMS.
Carlos Gamazo. Department of Microbiology, University of Navarra, Pamplona, Spain.
New generation avirulent vaccines are likely to be less immunogenic than
traditional attenuated vaccines. Therefore, they require appropriate adjuvants.
Vaccine delivery systems, such as emulsions, microparticles, ISCOMs and
liposomes, are a new class of adjuvants that mainly function to target associated
antigens into antigen presenting cells. Biodegradable microspheres are spherical
polymeric particles which contain a drug dispersed throughout the matrix. The most
widely used polymers for biodegradable microspheres are aliphatic polyesters made
of lactide (PLA) and glycolide (PLGA). Biodegradable microspheres are useful to
prolong and control the release of certain drugs and to target drugs to specific
infection sites. PEC Microparticles – Hydrophobicity - In vitro stability - Do not acidify
- Excellent tissue compatibility - Low cost. This review will focus on recent
developments in vaccine delivery systems for immunoprophylaxis of brucellosis.
Currently in use vaccines against Brucella spp. display some problems related
with its residual virulence. Therefore, development of fully avirulent vaccines is
justified with the subcellular vaccines representing one of the most interesting
approaches. An antigenic extract of Brucella ovis (HS), enriched in
lipopolysaccharide, phospholipids and outer membrane proteins, was encapsulated
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Brucellosis 2003 International Research Conference