What is included in a tick vaccine? - briefly
«Tick vaccines contain purified or recombinant tick‑salivary antigens that provoke a protective immune response, combined with an adjuvant (often an oil‑in‑water emulsion) and stabilizing agents such as sugars or amino acids». These components together decrease tick attachment, feeding efficiency, and the transmission of tick‑borne pathogens.
What is included in a tick vaccine? - in detail
A tick vaccine is formulated to induce immunity against pathogens transmitted by ticks and, in some cases, to reduce tick attachment itself. The preparation contains several defined categories of ingredients, each serving a specific function.
The active component consists of antigens that mimic tick‑borne microorganisms or tick salivary proteins. Typical antigenic forms include:
- Recombinant proteins derived from Borrelia, Anaplasma, or Rickettsia species.
- Synthetic peptides representing conserved epitopes of tick salivary glands.
- Inactivated whole‑cell extracts when a broad immune response is required.
Adjuvants amplify the immune reaction to the antigens. Commonly employed adjuvant systems are:
- Aluminium salts (aluminium hydroxide or aluminium phosphate).
- Oil‑in‑water emulsions such as MF59 or Montanide.
- Saponin‑based formulations like QS‑21.
- Toll‑like receptor agonists (e.g., CpG oligodeoxynucleotides).
Stabilizers preserve antigen integrity during storage and handling. Frequently used stabilizers are:
- Disaccharides (sucrose, trehalose).
- Gelatin or serum albumin.
- Polyols (mannitol).
Preservatives prevent microbial contamination of multi‑dose vials. Accepted preservatives include:
- Thimerosal (organic mercury compound).
- Phenoxyethanol.
- Benzyl alcohol.
Excipients adjust the solution’s physicochemical properties. Typical excipients are:
- Buffer systems (phosphate‑buffered saline, citrate).
- Isotonic agents (saline, lactated Ringer’s solution).
- Surfactants (polysorbate 80) to maintain homogeneity.
Optional delivery enhancers may be incorporated to target specific immune pathways:
- Carrier proteins such as keyhole‑limpet hemocyanin.
- Liposomal or nanoparticle carriers for controlled release.
- Biodegradable polymers (PLGA) for sustained antigen presentation.
Each component is selected based on regulatory standards, stability requirements, and the desired immunological profile, ensuring that the vaccine delivers a consistent and effective protective response against tick‑associated diseases.