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Multivalent approach for the improvement of inactivated vaccines against small ruminant diseases in Africa (MultiVacc); focus on the development of an improved CCPP vaccine

Manso-Silvan L., Wesonga H.. 2023. Kruger Park : IVVN, 1 p.. International Veterinary Immunology Symposium (IVIS2023). 13, 2023-11-17/2023-11-21, Kruger National Park (Afrique du Sud).

Contagious caprine pleuropneumonia (CCPP) is a severe respiratory disease of goats and wild ruminant with a great economic impact on livestock production in fragile rural economies, particularly in sub-Saharan Africa. The current CCPP vaccine consists of an inactivated bacterin based on Mycoplasma capricolum subsp. capripneumoniae (Mccp) whole-cell antigens inactivated and adjuvanted with saponin. Mccp is a fastidious organism and antigen yield in culture is very low, whereas the concentration of Mccp protein needed for successful protection is very high, resulting in excessive production costs for this vaccine, particularly when we consider the target market. Unfortunately, this has led to low quality commercial vaccines containing very limited amounts of Mccp proteins. Furthermore, the concentration of crude saponin required for protection is incompatible with current safety standards. Improved vaccines with reduced production costs and improved safety and thermostability are urgently needed for the control of CCPP. During the IDRC-funded project “MultiVacc”, a much faster growing, but extremely closely related Mycoplasma capricolum subsp. capricolum (Mcc) strain from Ethiopia was assessed as candidate seed for an improved CCPP vaccine. Seed replacement resulted in at least three times higher yield of specific mycoplasma antigens, shorter culture time and less supplements in medium necessary for growth, while the efficacy of the vaccine, as assessed by infections challenge in goats, was not affected. Furthermore, the replacement of saponin by Montanide oil adjuvant from SEPPIC conferred improved safety and stability to the vaccine, while the concomitant administration of a classical peste des petits ruminants (PPR) vaccine with the Mcc vaccine showed no interference with either PPR or CCPP protection (as demonstrated by serology and infectious challenge respectively). The challenges encountered during this project, the technology applied, the main success and pers

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