Evaluation of safety and immunogenicity of inactivated whole culture contagious caprine pleuropneumonia trial vaccine in National Veterinary Institute, Ethiopia

Contagious caprine pleuropneumonia (CCPP) is a fatal disease of goats occurring in many countries of Africa and Asia where the total goat population is more than 500 million. Vaccination is the most cost effective technique in the control of CCPP than any other control measures. In National Veterinary Institute (NVI) inactivated mycoplasma protein based vaccine obtained by centrifugation has been in use since many years. This study focuses on evaluating the safety and immunogenicity of inactivated whole culture CCPP vaccine currently developed in the NVI. Twenty six Mycoplasma capricolum subspecies capripneumoniae (Mccp) antibody free goats were used to evaluate the safety and immunogenicity of inactivated whole culture CCPP trial vaccine. The trial vaccine was prepared from culture of Mccp vaccinal seed grown in Mycoplasma specific hayflick media using spinner bottle. The protein content for one milliliter of whole culture was checked and found to be more than the minimum recommended dose (0.15 mg per dose). The culture was inactivated by 37% formalin at proportion of 0.5% of whole culture and adjuvanted by saponin at final concentration of 0.3%. The experimental animals were distributed into four groups: The group A consist of five goats for safety and all the other groups consists of seven animals each with group B for trial vaccine, group C for positive control and group D for negative control for immunogenicity trials. The goats were observed for two months for safety and immunogenicity evaluation during which serum samples were collected for immunogenicity and tested by using competitive Enzyme Linked immunosorbent Assay (cELISA) test. The results indicated that out of 7 goats vaccinated with trial vaccine, the mean sero-positivity was 60.71% while 7 goats vaccinated with the positive control showed mean sero-positivity of 58.86%. The analysis showed no significant difference between mean sero positivity of trial vaccine and positive control (P>0.05) as indicated by sero-conversion. The mean percent inhibition (PI) of trial inactivated whole culture CCPP vaccine vaccinated goats was 61.52% while the mean PI for positive control vaccine vaccinated group was 51.86%. In contrast the non-vaccinated controls showed mean PI of 40.65% which is significantly less than percent inhibition of the vaccinated groups (p=0.000). The body temperature and clinical observation of safety tested animals and other immunogenicity tested goats showed absence of any abnormality after vaccination both in vaccinated and controls. This study which was novel in its nature concluded that the trial inactivated whole culture ccpp vaccine is equally immunogenic as that vaccine already in use, the non-whole culture concentrated CCPP vaccine, and could be used for mass vaccination after conducting field immunogenicity trial.