Peer-reviewed veterinary case report
Long-lasting immunity in dogs after live vaccine for tick infection
By Madesh, Swetha et al.·Published in Vaccine·2025·Department of Diagnostic Medicine/Pathobiology, United States·View original on PubMed →
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Original publication title: Prolonged immune response to tick-borne Ehrlichia chaffeensis infection using a genetically modified live vaccine.
- Species:
- dog
Plain-English summary
A group of dogs was vaccinated with a modified live vaccine to protect against Ehrlichia chaffeensis, a tick-borne infection that can cause serious illness. After being exposed to infected ticks at various times over a year, the vaccinated dogs were able to clear the infection quickly and showed fewer signs of illness compared to unvaccinated dogs. The vaccine not only helped the dogs fight off the infection but also maintained strong immune responses throughout the year. This suggests that the vaccine could be an effective way to protect dogs from this tick-borne disease.
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Abstract
Ehrlichia chaffeensis, a tick transmitted rickettsial bacterium, causes monocytic ehrlichiosis in humans and dogs. Earlier, we demonstrated that dogs immunized with a mutant strain of E. chaffeensis having a functional disruption in the gene encoding the phage head-to-tail connector protein serves as a modified live vaccine (MLAV) capable of inducing immunity against intravenous and tick-transmitted infection challenges within one month of vaccination. In this follow-up investigation, we assessed the duration of MLAV-induced immunity for one-year period against tick-transmission infection challenge. Dogs vaccinated with the MLAV were subsequently exposed to wild-type E. chaffeensis via tick transmission at 4-, 8-, and 12-months post-vaccination. Unvaccinated controls showed higher infection rates during the one-month assessment following infection. In contrast, MLAV-immunized dogs rapidly cleared infections and exhibited significantly fewer systemic bacterial infections compared to unvaccinated controls. Robust E. chaffeensis-specific IgG and CD4 T-cell responses persisted throughout the assessment period. Our findings underscore the efficacy of MLAV in providing natural hosts with protection against E. chaffeensis infection for up to one year following infected tick exposure.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/39826432/