Approaches towards therapeutic development against chronic brucellosis in a mouse model

Brucellosis is the most common zoonotic disease worldwide. The intracellular localization of Brucella hinders the action of drugs that poorly cross cell membrane barriers. Additionally, when the immune response fails to clear the infection, chronic brucellosis ensues that becomes more challenging to treat with antibiotics. Therefore, two approaches, intracellular drug delivery and immunostimulation, have been explored in this dissertation, with an aim to develop a better therapeutic against Brucella infection in mice. First, to overcome the cell membrane barriers, drug loaded nanoparticles were tested to treat B. melitensis infection in mice. Gentamicin loaded block-ionomer complexes (BICs) and magnetite block-ionomer complexes (MBICs) were tested in vitro and along with clusters of MBICs (MBIClusters) were tested in vivo as tools to deliver gentamicin intracellularly. While these complexes showed very high efficacy compared to free gentamicin against Brucella in macrophage cell culture, they failed to show similar efficacies in mice. Histopathological examination of kidneys from mice treated with MBICs or MBIClusters showed deposition of brown pigment-laden macrophages in peri-renal adipose tissue and the pigment was confirmed as MBICs or MBIClusters based on special staining for iron. Additionally, it was found that doxycycline-gentamicin (DG) treatment results in better clearance of Brucella from infected mice compared to doxycycline alone. Secondly, two vaccine candidates, irradiated B. neotomae (IBN) and outer membrane vesicles (OMVs), were tested as immunostimulants to treat chronic B. melitensis infection in mice in combination with antibiotics. The non-ionic block co-polymer Pluronic P85, when mixed with OMVs as an adjuvant showed significantly higher protection against B. melitensis challenge in vaccinated mice compared to those vaccinated with OMVs alone. When tested as immunostimulants, there was no additive effect of vaccines and antibiotics on Brucella clearance from mice. However, IBN enhanced the production of IFN-γ while OMVs were associated with enhanced antibody production. This enhancement in the immune system resulted in the control of Brucella growth after the end of treatment. When given without antibiotics, vaccine alone failed to clear any Brucella from infected mice. The use of these vaccine candidates in combination with antibiotics shows a potential to prevent relapses in cases of brucellosis.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Veterinary Medical Sciences

Department dc:contributor.department

Veterinary Medical Sciences

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2012

Author dc:creator

• Jain, Neeta

Chair dc:contributor.committeechair

• Sriranganathan, Nammalwar

Committee members dc:contributor.committeemember

• Huckle, William R.
• Riffle, Judy S.
• Boyle, Stephen M.

• Brucella
• Brucella neotomae
• antibiotics
• nanoparticles
• Brucella melitensis
• adjuvants
• subunit vaccines
• immunotherapy

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en_US

Dc Identifier Other

etd-01302012-201421

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/77039