Efficacy of Carbomer as a Stabilizer for Lyophilized attenuated Peste des Petits Ruminants (PPR) vaccine

A Peste des petits ruminant (PPR) is a category of acute fulminating infectious viral disease, affecting seriously sheep and goats. It is caused by PPRV that classified within a Morbillivirus; family Paramyxoviridae. Vaccination is the cornerstone to protect sheep and goats against such diseases. The present work aims to provide a highly potent attenuated lyophilized PPR vaccine where three formulae were prepared including formula (1) stabilized with 1% carbomer and 2% peptone; formula (2) stabilized with 0.5% carbomer and formula (3) stabilized with 2% peptone; 10% sucrose and 0.27% dihydrogen orthophosphate. The three lyophilized PPR vaccine formulae had compact similar cacks without different shape appearances. Also, the three formulae were found to be free from foreign contaminants (aerobic and anaerobic bacteria; fungi and mycoplasma) having no significant difference in the virus titer pre- and post-lyophilization. Reduction in the virus titer post lyophilization was 0.25, 0.5 and 0.5 log10 TCID50/ml in relation to formula 1; 2 and 3 respectively. Although formula (2) induced the peak PPR serum neutralizing antibody titer earlier (128 by the 3rd week) than the other 2 formulae (128 by the 4th week); the potency test revealed that all vaccine formulae were potently inducing high protective PPR immune levels in vaccinated sheep up to 6 months post-vaccination. So, it could be suggested that carbomer accelerate the time to reach the peak of PPR antibody titers in vaccinated sheep.