Anne Chenchar
Aaron Zahne
D.J. Sandidge
Group Proposal
MICR 4321
October 8, 2017
Brucellosis Vaccination: assessing the stability and safety of a Nisin inducible plasmid expressing Brucella antigen in Lactococcos lactis
Summary:
Brucellosis is a worldwide bacterial disease that infects bison and elk herds found in the greater Yellowstone area in Wyoming, threatening the cattle herds with possible infection. negatively affects the Wyoming bovine ranching industry. Current vaccines against the pathogen do not provide total immunity, and some interfere with diagnostic testing. We propose using live Lactococcus lactis, a probiotic bacterium, to express an adhesin found in wild type Brucella abortus. Before this can be a viable vaccine candidate, experiments must show viability and safety of the Nisin expression system..A stable food-safe vector such as this, allows for quick, wide ranging, and robust immunization. The aims of this project are to gather data that this vaccine strain has normal growth along with adequate antigen expression. Also showing that the antibiotic resistance present in the plasmid remains inside the probiotic.
To date, no research has been done to explore vector response to bovine rumen conditions. Such research will provide knowledge for the field of probiotic vaccines. Dangerous pathogens acquiring and expressing resistance from the recombinant DNA is of great concern, and the extent of this problem is unknown. The rumen conditions may be unfavorable for the strain compared to the local residents, and various testing must show strain durability and plasmid accountability. Despite the challenges, we are expecting standard growth using this nisin-induced system. We aim to grow the vector-strain in conditions varying in pH, temperature, and microbial community, measuring if it has adequate survival capability. Rumen bacteria and pathogens grown alongside L. lactis will be reviewed for plasma expression, with the aim of quantifying the rate of transfer. Testing these variables will give understanding of the pressures and limits affecting the vaccine-strain, and if successful, ultimately leading to novel innovation and broad application in vaccination methods. .
Statement of Problem and Significance:
If efforts to eradicate this bacteria were halted due to the current risk of infection B. abortus presents to commercial livestock production, the cost of producing beef and milk would increase by $80 million annually (2). This issue is worsened by the fact that B. abortus can infect humans and is found in wild ruminants like elk and bison, but also infects the bovine population causing calves to be aborted or become chronically infected, acting as reservoirs for further herd infection. Even with current vaccination methods for cattle, which are an injection-based live attenuated strain, B. abortus is still an issue to livestock production. With these issues apparent, the scientific community is hard at work to find alternatives to vaccination of B. abortus. Probiotics are an avenue of investigation as a more widespread and efficient method of antigen delivery. If this work proves successful , costs of livestock vaccination could significantly drop allowing widespread vaccination not only in cattle herds, but potentially wild ungulates as well.
Introduction:
Relevant literature:
Brucellosis, caused by Brucella abortus results in spontaneous abortions in domestic animals, as well as wildlife (1). Two animals of importance for our study are domesticated cattle, and wild elk (3). With the prevalence of this pathogen in these species, and their interactions together, the cattle agricultural industry is under economic threat by the loss of fetal calves. Currently one vaccination is on the market for use, a live attenuated strain of B. abortus RB51(3). Although this vaccine is on the market for use in the agriculture industry it is only moderately efficacious as a cattle vaccine, and is not applicable to elk, serving as the wild reservoir for this pathogen(3). The elk infected with B. abortus develop a chronic infection, which spreads within their own population, and other ungulates that they come in contact with, damaging the populations (3). The current RB51 attenuated strain must be intravenously administered by a veterinarian, making wild animal vaccination extremely unlikely and human infection more likely. A probiotic vaccine would allow large-scale immunization through feed, and eliminate the risk of human infection by exposure.
Preliminary data:
Our preliminary data are based on the possible immune activating capability of a Type V protein named Hia in Brucella Strain RB51, an adhesin homolog of Heamophilus. Our group is using this gene inside a nicin induced expression system (NICE) present in the Strain Lactococcus lactis.
Conceptual Model: