Study on immunogenicity of combined sheep and goat pox and peste des petitis ruminants vaccines in small ruminants in Ethiopia

Abstract

The study was conducted at the National Veterinary Institute (NVI), Ethiopia, with the objective of evaluating the immunogenicity of combined peste des petits ruminants (PPR) and sheep and goat pox (SGP) vaccines under laboratory and field conditions for possible use of a cost efficient vaccine based disease control strategy. Vaccines of PPR and SGP were prepared using PPR75/1 (LK6 Vero74) and Kenyan sheep and goat pox (0180) strains separately as per NVI vaccine production protocol. Sera were collected from a total of 100 unvaccinated small ruminants (40 sheep and 60 goats) and screened for the presence of PPR and SGP virus specific antibodies. Then, animals that were found negative for the diseases were grouped, vaccinated, and clinically monitored by regular observations and by recording daily rectal temperature. Serum samples were collected at regular intervals for determination of sero-conversion. Challenge test was conducted separately for PPR and sheeppox vaccines and in combination of the two. Generally, vaccination against PPR and sheep pox using both combined and one vaccine alone conferred good protective efficacy. Both sheep and goats vaccinated against sheep pox using both combined vaccine and sheeppox vaccine alone were protected against challenge infection. The PPR trial showed that 50% of the control groups showed rise in body temperature and 37.5% of them died of PPR, while for sheep pox challenge group, 52.6% (n = 10/19) from the unvaccinated group showed typical pox lesion (fever, nodules) and 15.8% (n = 3/19) died of sheep pox. The serological test result show that vaccinated goats with PPR were sero-positive up to 75% and it reached 100% immediately post challenge, while sheep pox vaccinated groups showed up to 1/128 sero-positivity in serum neutralization test. Key words: Sheep and goatpox, PPR, vaccine, seroconversion, Ethiopia.