Abstract
Background:
Contagious caprine pleuropneumonia (CCPP) is a transboundary disease of goats caused by the Mycoplasma capricolum subspecies capripneumoniae (Mccp). Compared with any other control measures, vaccination is the most cost-effective technique for the control of CCPP. The selection of effective adjuvants is crucial for ensuring the quality of the vaccine and its protective efficacy. Saponin is the most commonly used adjuvant, with its drawbacks like its potential for dose-related toxicity, low chemical stability, low extraction yield and irritation to laboratory workers. However, the possibility of using oil emulsion adjuvants as alternatives to saponin have not been considered, even though, oil in water adjuvants is relatively safer and less expensive.

Aim:
This study aimed to evaluate the immunogenicity and safety of selected adjuvant formulations for improving the CCPP vaccine.

Methods:
For this purpose, different adjuvants (15% Emulsigen, 15% Emulsigen-D, 15% Emulsigen-P, 10% Carbigen, 3% saponin and 0.3% saponin were evaluated after immunized to Mccp antibody-free goats. The antibody response against each vaccine was evaluated via competitive enzyme-linked immunosorbent assay (c-ELISA). In addition, adverse effects following the administration of the vaccines were recorded.

Results:
The experimental study revealed that 0.3% saponin resulted in the highest immune response (mean percentage of inhibition [PI] value=74.45), followed by 3% saponin (66.92%), Emulsigen (66.90%) and Carbigen (66.45%). The results did not reveal statistically significant (p>0.05, ANOVA) differences in efficacy. Compared with the non-vaccinated groups, the Empulsigen-P and Emulsigen-D groups elicited a sufficient immune response (mean PI=59.57 and 56.77). Notably, 3% saponin caused irritation and high fever in some animals. The carbigen did not undergo any reaction, including the localized swelling observed in the other groups.

Conclusion:
These findings confirmed that oil adjuvants, particularly Carbigen and Emulsigen, are valuable for providing a sufficient immune response and improved safety. Consequently, these oil adjuvants can be used as alternatives to saponin in CCPP vaccines.

Key words: Adjuvant; CCPP; C-ELISA; Goat; Vaccine.