Statement of Problem and Significance:
B. abortus is a huge issue in commercial livestock production, that if efforts to eradicate this bacteria were halted, the cost of producing beef and milk would increase by $80 million annually (1). This issue is worsened by the fact that B. abortus can infect humans as well. 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 is successful, costs of livestock vaccination could significantly drop and human infections could be a thing of the past. DJ sandidge
Introduction:
Brucellosis, caused by Brucella abortus results in spontaneous abortions in domestic animals, as well as wildlife. Two animals of importance for our study are domesticated cattle, and elk (1). 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(1). 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(1). The elk infected with B. abortus develop a chronic infection, which spreads within their own population, and other populations of ungulates that they come in contact with. These include cattle and bison, damaging both populations (1).
There have been steps within the research community to advance an alternative vaccine using a non-pathogenic microbe that expresses the B. abortus surface antigens. Thus creating a probiotic vaccine that would reside in the gut of the rumens allowing safe protection from B. abortus. Within the confines of our project there are unknown questions that leave gaps in our knowledge. Initially we are attempting to test the transformed L. lactis against rumen and gastrointestinal conditions, from research we are able to gain knowledge of some conditions that will be faced, however there still lies many unknowns that may be species oriented, or even individual. Similar to this we will be testing which environmental factors in a rumen would cause the bacteria to lyse, releasing the naked plasmid. In the circumstance that the plasmid was released we would also seek to understand what would cause the plasmid to become denatured or cause the active plasmid to become absorbed by other rumen commensals. We also will be seeking to better understand the growth curve of the transformed L. lactis in comparison to the wild type strain. Our preliminary data ranges from previous studies on both the B. abortus surface antigens that would express themselves the best on a non-pathogenic bacterium to other papers about the use of the NICE vector for efficacious results. With previous studies enumerating how L. lactis is a potential candidate for creating a vaccine using the probiotic qualities of the microbe we felt this would be our most successful host for the NICE vector(2).
Aaron's
Introduction:
The search for a safe Brucellosis vaccine with sufficient immune activation continues today with no candidates changing the game. Alternative vaccines have focused on presenting antigens such as outer membrane proteins, superoxide dismutases, cell envelopes, and lipopolysaccharides (LPS), but these have failed to gain traction and commercial use in Brucellosis prevention (Saez 2012). As intracellular pathogens, Brucella species rely heavily on their specialized (LPS) to evade host detection, making it a targeted portion of the bacteria. Mutated strains with “rough” LPS have been the source of wide scale vaccination. These live attenuated species of Brucella are safe for cattle 4 months and older, but unsafe for less than 3-month-old calves and pregnant cattle. (Lalsiamthara 2017). The RB51 strain is infectious to humans, and with modified LPS can elude diagnostic detection. The current system of using an attenuated strain lacks efficiency and dependability.
Our preliminary data [RW1] is 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) plasmid present in the Strain
Lactococcus lactis. Using a live food grade bacterium with recombinant DNA as a vaccination method is not a new idea, in fact this has been proposed since the late 90s, but has never been implemented as a standard vaccine (Schurig 2002). Our group aims to use
Lactococcus lactis as a vector for
Brucella antigen, and offer mucosal immunity via a live oral vaccine.
L. lactis is a common bacterium that is used to make yogurt, and other lactose products. This food safe probiotic rarely colonizes the host, and would not upset the rumen of the vaccinated animals. The NICE plasmid inside
L. lactis will encode the
Brucella antigen, along with chloramphenicol resistance, allowing us to test the
L. lactis for proper plasmid uptake. For this to be a vaccine candidate, it must show a willingness to grow in the rumen conditions of the cattle. The chloramphenicol resistance gene, if spread, could be a source for pathogenic antibiotic resistance. This aspect of the vaccine is being evaluated and characterized in depth, ensuring safe passage through the gastrointestinal tract of the vaccinated animal. To be effaceable, the probiotic must retain its genetic information.
The live vaccine in the form of Lactococcos lactis is a possible route to immunity without the risk of fetal abortion or human infection. Current methods require intravenous procedures, and unnecessary risk to those administering. The ability to use an oral vaccine would extend the range of those immunized to possibly wild elk and bison interacting with the cattle. Understanding the role a rumen environment will have on the Strain is required to ensure a stable vector capable of supplying immune response. Growth curves will show the effects a rumen environment and its activity can cause.
Empirical Model:
Object, Hypothesis, and Specific Aims:
Methods:
Timeline:
Frozen Stalk list
- E. coli, Sept 21, 2017
- B. subtillus, Sept 21, 2017
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Scope: Vaccination in ungulates both domesticated and wild (cattle and elk).