A heterologous prime/boost immunisation strategy protects against virulent E. ruminantium Welgevonden needle challenge but not against tick challenge

• Published in: Vaccine Vol. 26; no. 34; pp. 4363 - 4371
• Main Authors: Pretorius, A, van Kleef, M, Collins, N.E, Tshikudo, N, Louw, E, Faber, F.E, van Strijp, M.F, Allsopp, B.A
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 12.08.2008; Elsevier
• Subjects: Allergy and Immunology; Animals; Applied microbiology; Bacterial Proteins - genetics; Bacterial Proteins - immunology; Bacteriology; Biological and medical sciences; Cell Proliferation; Disease Transmission, Infectious - prevention & control; Disease Vectors; DNA vaccination; Ehrlichia ruminantium; Ehrlichia ruminantium - immunology; Fever - etiology; Fundamental and applied biological sciences. Psychology; Genetic Vectors; Heartwater Disease - immunology; Heartwater Disease - prevention & control; Immunization, Secondary - methods; Interferon-gamma - biosynthesis; Lumpy skin disease virus - genetics; Lymphocytes - immunology; Microbiology; Miscellaneous; Prime/boost immunisation; Sheep; Sheep Diseases - immunology; Sheep Diseases - prevention & control; Survival Analysis; Ticks - microbiology; Time Factors; Vaccines, antisera, therapeutical immunoglobulins and monoclonal antibodies (general aspects); Vaccines, DNA - immunology; Vaccines, Subunit - immunology; Ehrlichia ruminantium; DNA vaccination; Prime/boost immunisation; Ehrlichiaceae; Rickettsiales; Immunization; Needle; Bacteria; Ehrlichieae; Genetic vaccine; Ehrlichia; Ehrlichia ruminantium,DNA vaccination,Prime/boost immunisation
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/j.vaccine.2008.06.006

Abstract Heterologous prime/boost immunisation strategies using the Ehrlichia ruminantium 1H12 pCMViUBs_ORFs [Pretorius A, Collins NE, Steyn HC, Van Strijp F, Van Kleef M, Allsopp BA. Protection against heartwater by DNA immunisation with four Ehrlichia ruminantium open reading frames. Vaccine 2007;25(12):2316–24] were investigated in this study. All the animals immunised twice with a recombinant (r) DNA cocktail of four 1H12 pCMViUBs_ORFs followed by a r1H12 protein and those immunised 3× with 1H12 plasmid rDNA showed 100% protection against a virulent E. ruminantium Welgevonden needle challenge. In addition, 90% of the sheep immunised twice with rDNA and boosted with r1H12 lumpy skin disease virus (LSDV) survived. Only the lymphocytes isolated from the r1H12 protein boost group showed specific proliferation and increased interferon (IFN)-γ expression. In contrast, only 20% protection was obtained in animals immunised with the rDNA prime/r1H12 protein boost when subjected to natural tick challenge in the field. Thus this heterologous prime/boost immunisation strategy had not conferred any significant protection against a field challenge.