Recipient Organization
NORTHERN ARIZONA UNIVERSITY
(N/A)
FLAGSTAFF,AZ 86011
Performing Department
(N/A)
Non Technical Summary
Cattle fever is a deadly disease of cattle that is widespread in Mexico and at high risk of being reintroduced to the U.S. This would cause major losses for our cattle industry and greatly increase beef prices for consumers. The parasite that causes cattle fever can only be transmitted by cattle fever ticks, which are currently controlled using chemical treatment. Unfortunately, these ticks are developing resistance to all chemicals used in Mexico and the U.S. Our project will address this problem by developing a new anti-tick vaccine for cattle. We will use laboratory methods to test vaccine candidates that produce a strong immune response in cattle, including the production of cattle antibodies that directly attack the tick, as well as bacteria in their guts that assist ticks with processing blood meals. We expect that vaccinating cattle will significantly negatively impact tick feeding and reproduction, which will greatly reduce local tick populations and the risk of cattle fever. The anticipated impacts from this work will prevent cattle fever from becoming re-established in the U.S., thereby protecting cattle herds and livestock producers from potentially devastating losses.
Animal Health Component
(N/A)
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Goals / Objectives
The major goal of this project is to develop a novel, effective anti-tick vaccine for cattle that targets the cattle fever tick (Rhipicephalus microplus) and its obligate Coxiella-like endosymbiont, thereby preventing the re-emergence of bovine babesiosis in US. cattle. To achieve this overarching goal, the project will pursue the following two specific objectives:Identify and prioritize vaccine antigen candidates: We will perform genomic and proteomic analyses on the Coxiella-like endosymbiont (CLE) of R. microplus to identify protein candidates that are highly conserved across tick populations and predicted to be highly immunogenic for the bovine immune system. These candidate antigens will be prioritized based on bioinformatic criteria (e.g., sequence conservation, surface exposure, immunogenic epitopes) and laboratory screening of a large number of tick samples (n=960) to identify any differences in the candidate antigens across tick populations.Evaluate vaccine efficacy in cattle trials: We will use the top-ranked CLE antigen candidates in controlled vaccination trials of cattle. Cattle will be immunized and then experimentally infested with R. microplus larvae to test vaccine efficacy. We will monitor tick attachment, feeding success, and reproduction on vaccinated versus control (unvaccinated) cattle. Immune responses (such as antibody titers) in the vaccinated cattle will be measured to correlate with protection. This objective will validate which antigens confer significant protection to cattle against tick infestation and thus can serve as components of an effective anti-tick vaccine.These objectives are designed to be specific and attainable within the 3-year project period and with the available resources. Successful completion of Objective 1 will yield a list of promising antigen targets, and Objective 2 will determine the actual protective value of those targets, directly supporting the project's major goal.
Project Methods
This project will be conducted with a multidisciplinary approach that combines genomic, immunological, and field-trial methodologies. Key methods and steps include:Generate sequence data from key genes and proteins, analyze these data with bioinformatic analyses, and develop new vaccine formulations based on highly ranked proteins. Conduct cattle vaccination and tick challenge studies and run post-experimental immunological assays to quantify the IgG antibody response and confirm the presence of targeted CLE proteins in tick samples. Perform quantitative PCR assays to evaluate if the amount of CLE bacteria in tick eggs is reduced after female ticks feed from a vaccinated bovine host. Conduct a 16S rRNA gene analysis to determine if adult female ticks fed on a vaccinated host experience a strong shift in microbiome bacteria.Screen candidate proteins for amino acid conservation: We will use DNA sequencing and bioinformatics techniques to characterize key proteins of the CLE of R. microplus ticks. We will start by generating amplicon sequence data from a large number of tick samples (n=960). We will then analyze these data with bioinformatic analysis to evaluate conservation at specific CLE proteins. Finally, we will use protein modeling software to evaluate immunogenicity of surface-expressed peptides and rank the antigen candidates.Vaccine Development: Using the prioritized antigens, we will use highly ranked recombinant proteins to formulate experimental vaccines for cattle. We will immunize groups of experimental and control cattle (n=5 each) at two time points (days 0 and 21) and use ELISA analysis to quantify IgG antibodies throughout each 70-day experiment. All procedures will follow biosafety and animal welfare guidelines, and we will use standard veterinary protocols for animal care.Tick Challenge Trials: We will use 0.5g of larval R. microplus (~10,000 ticks) from the La Joya lab colony per cow, separated into two cloth chambers glued to shaved skin patch. Ticks will remain on cattle until adult females are engorged (~3 weeks), at which time females that drop from cattle will be collected daily (~21-25 days post infestation). We will record multiple parameters of female tick fitness in control vs. vaccinated groups, including the number that survive, weight, egg mass weight, egg hatching success, larval weight, and larval survival. All live engorged female ticks will be disinfected, counted, weighed, and placed in Petri dishes to oviposit for thirteen days at 26°C and 80% humidity. The total combined tick egg mass collected from each single cow will be collected and weighed, then incubated to test egg viability (hatching success) A reduction in these metrics in the vaccinated group (relative to controls) will indicate vaccine efficacy.Data Analysis: The results from laboratory assays and animal trials will be rigorously analyzed. We will use statistical analyses (e.g., t-tests or ANOVA for comparing tick counts and weights between groups, survival analysis for tick mortality rates, etc.) to determine the significance of any differences observed. We will perform quantitative PCR assays to evaluate if the amount of CLE bacteria in eggs is reduced after female ticks feed from a vaccinated bovine host and conduct a 16S rRNA gene analysis to determine if adult female ticks fed on a vaccinated host experience a strong shift in microbiome bacteria.Project Management and Milestones: We have a clear timeline with milestones to ensure the project stays on track. Year 1 milestones include completion of antigen identification and initial immunogenicity screening; Year 2 focuses on vaccine formulation and a preliminary cattle trial; Year 3 includes the main efficacy trial and data analysis. Regular team meetings (monthly) and annual reviews with stakeholders (e.g., progress report to USDA-NIFA program officers, and consultations with APHIS experts) are planned as part of the method to keep the project aligned with objectives and to incorporate external feedback.Efforts to Disseminate Knowledge: In addition to scientific publications and conference presentations, we will use more accessible venues to disseminate findings to broader audiences. This includes preparing summary reports or briefs for industry stakeholders and possibly leveraging extension services at collaborator institutions to translate results for rancher-oriented newsletters or webinars. By the end of the project, we aim to have at least one outreach article or presentation geared toward non-scientists (for example, a talk at a cattlemen's association meeting or an extension bulletin explaining the vaccine concept and results in lay terms).Evaluation Plan: We will evaluate the success of the project through both technical and impact metrics:Research success metrics: First and foremost, we will determine if we met our objectives. This will be checked by tracking if we identified the expected number of viable vaccine candidates (for instance, at least 3-5 strong antigens) and if we demonstrated a statistically significant reduction in tick burden on vaccinated cattle. Each objective's completion is a checkpoint - for example, completion of genome analysis by the target month, etc. - and will be documented in progress reports.Outcome metrics: We will collect data to measure outcomes such as change in knowledge and action. For knowledge, metrics will include number of publications submitted and any inquiries or collaborations that arise (indicating interest in our findings). For action, while a vaccine won't be on the market by the end of this project, we can measure intermediate actions like interest from a biotech company or additional funding to continue vaccine development as indicators that our work is influencing the field. We will also evaluate the training outcome by tracking student achievements (degrees earned, conference presentations given by students, etc.).Impact projection: Although long-term impact (change in condition at the industry level) will not fully materialize during the project, achieving a proof-of-concept (efficacy in an experimental setting) is itself an impactful milestone that we will use as a springboard to seek further funding or partnerships for scaling up.Final report: At the end of the project, a comprehensive evaluation report will be prepared, relating each of our project outcomes back to the original problem statement. We will assess how our results contribute to solving the problem of cattle fever ticks and identify next steps needed to reach full implementation. Success will be defined not just by scientific findings, but also by how well we have positioned the vaccine approach for real-world use (e.g., having a clear path forward for larger trials or regulatory consideration).