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Published on: November 1, 2011
Rift Valley Fever vaccine strategies: Enhanced stability of RVF Clone 13
Boitumelo Moetlhoa1, Mabotse Tjale2, Alri Pretorius3
1Onderstepoort Biological Products (OBP) SOC Ltd, 100 Old Soutpan Road, Onderstepoort, 0110, South Africa; DSI/NWU Preclinical Drug Development Platform (PCDDP), Faculty of Health Sciences, North-West University, Potchefstroom 2520, South Africa.
This study enhanced the Rift Valley Fever virus (RVF) Clone 13 vaccine's stability using lyophilization with sucrose or lactose stabilizers. Sucrose-based formulations demonstrated superior antigen stability and comparable immunogenicity, offering improved vaccine handling for livestock.
Area of Science:
- Veterinary Virology
- Vaccine Development
- Immunology
Background:
- Rift Valley Fever virus (RVFV) causes significant economic losses in livestock due to RVF disease.
- Regular vaccination is crucial for livestock immunity against RVFV.
- The current live attenuated RVF Clone 13 vaccine is heat-labile, requiring strict storage conditions.
Purpose of the Study:
- To enhance the thermal stability of the RVF Clone 13 vaccine strain using lyophilization with lactose and sucrose stabilizers.
- To evaluate the immunogenicity and cellular immune responses of the novel vaccine formulations.
- To investigate Pheroid® technology as a potential adjuvant to improve vaccine efficacy.
Main Methods:
- Lyophilization of RVF Clone 13 vaccine with lactose and sucrose stabilizers.
- Determination of glass transition temperature (Tg) and residual moisture content.
- Assessment of antigen titres, humoral immunity, and cellular immune responses (T-cell proliferation, IFN-γ expression) in vaccinated animals.
- Evaluation of Pheroid® adjuvant in Merino sheep.
Main Results:
- Sucrose-based RVF vaccine exhibited a higher glass transition temperature (97.0°C) and lower residual moisture (<2%) compared to lactose (83.5°C, >2%).
- The sucrose formulation maintained higher antigen titres post-lyophilization.
- All vaccine formulations, with or without Pheroid®, induced comparable protective humoral immunity.
- Cellular immunity was primarily mediated by CD8+ T-cells expressing IFN-γ, indicating Class I antigen presentation.
Conclusions:
- Sucrose-based lyophilized RVF Clone 13 vaccine offers enhanced stability for improved storage and handling.
- The vaccine formulations are safe and elicit protective immune responses in livestock.
- Cellular immunity against RVF involves a robust CD8+ T-cell response via the Class I pathway.
