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- Title
Development of a subcutaneous ear implant to deliver an anaplasmosis vaccine to dairy steers.
- Authors
Curtis, Andrew K; Reif, Kathryn E; Kleinhenz, Michael D; Martin, Miriam S; Skinner, Brandt; Kelly, Sean M; Jones, Douglas E; Reppert, Emily J; Montgomery, Shawnee R; Narasimhan, Balaji; Anantatat, Tippawan; Jaberi-Douraki, Majid; Coetzee, Johann F
- Abstract
Bovine anaplasmosis is the most prevalent tick-transmitted disease of cattle worldwide and a major obstacle to profitable beef production. Use of chlortetracycline-medicated feed to control active anaplasmosis infections during the vector season has raised concerns about the potential emergence of antimicrobial resistance in bacteria that may pose a risk to human health. Furthermore, the absence of effectiveness data for a commercially available, conditionally licensed anaplasmosis vaccine is a major impediment to implementing anaplasmosis control programs. The primary objective of this study was to develop a single-dose vaccine delivery platform to produce long-lasting protective immunity against anaplasmosis infections. Twelve Holstein steers, aged 11 to 12 wk, were administered a novel 3-stage, single-dose vaccine against Anaplasma marginale , a major surface protein 1a. The vaccine consisted of a soluble vaccine administered subcutaneously (s.c.) for immune priming, a vaccine depot of a biodegradable polyanhydride rod with intermediate slow release of the vaccine for boosting immune response, and an immune-isolated vaccine platform for extended antigen release (VPEAR implant) deposited s.c. in the ear. Six calves were randomly assigned to 2 vaccine constructs (n = 3) that featured rods and implants containing a combination of 2 different adjuvants, diethylaminoethyl (DEAE)-Dextran and Quil-A (Group A). The remaining 6 calves were randomly assigned to 2 vaccine constructs (n = 3) that featured rods and implants containing the same adjuvant (either DEAE-Dextran or Quil A) (Group B). Twenty-one months post-implantation, calves were challenged intravenously with A. marginale stabilate and were monitored weekly for signs of fever, decreased packed cell volume (PCV) and bacteremia. Data were analyzed using a mixed-effects model and chi-squared tests (SAS v9.04.01, SAS Institute, Cary, NC). Calves in Group A had higher PCV than calves in Group B (P = 0.006) at day 35 post-infection. Calves in Group A were less likely to require antibiotic intervention compared with calves in Group B (P = 0.014). Results indicate that calves exhibited diminished clinical signs of anaplasmosis when antigen was delivered with a combination of adjuvants as opposed to a single adjuvant. This demonstrates the feasibility of providing long-lasting protection against clinical bovine anaplasmosis infections using a subcutaneous ear implant vaccine construct.
- Subjects
CARY (N.C.); SAS Institute Inc.; DRUG resistance in microorganisms; ANAPLASMA marginale; VACCINES; BEEF cattle; ANAPLASMOSIS; BIODEGRADABLE nanoparticles; DAIRY processing
- Publication
Journal of Animal Science, 2020, Vol 98, Issue 6, p1
- ISSN
0021-8812
- Publication type
Article
- DOI
10.1093/jas/skz392