Peste des petits ruminant (PPR) is a highly contagious newly developing disease of Small ruminants (sheep and goats). Currently the poor small ruminant’s farmers in Pakistan are facing huge economic losses due to PPR virus. In Pakistan PPR causes economic losses of Rs. 20.5 billion annually. The objectives of present study were to develop a cost effective sero-diagnostic assay for PPR (active haemagglutination inhibition and passive haemagglutination inhibition) and determination of comparative efficacy of active and passive haemagglutination inhibition assay (HI and PHA respectively) for detection of PPR virus infection.
In the present study, n= 300 sera samples were collected from sheep and goats during the (15 Februry 2016 to 2 January 2017).The serum samples were collected from kotli AJK :20(8 goats and 12 sheep),from gilgit:30 serum (20 goats and 10 sheep),from mansehra:22 serum (13 goats and 9 sheep),from mithi:112 (60 goats and 52 sheep) and 116 serum samples (88goats and 28 sheep) from Dhera ghazi khan.None of the animal was known to have been vaccinated against PPR previously or at the time of sampling.
These samples were collected from animals showed symptoms of PPR suggestive of PPR disease as well as from healthy animals. The sera were transferred into sterile tubes and were preserved on ice packs while shifting to the laboratory. PPR virus isolate was originally isolated from an outbreak in Taxila village, district Rawalpindi, the isolate was attenuated serially onto the Vero cell lines up to 20 passages. After, which antigen was titrated using a micotiter haemagglutination (HA) test with chicken RBCs and stored at -70◦c until use as a PPR antigen in a HI test.
In this study Active haemagglutination inhibition (HI) and passive haemagglutination inhibition were developed. The Haemagglutination Assay was standardized by different factors i.e. diluents, Temperature of incubation, Time of Incubation and concentration of Chicken R.B.C̓s. An additional test passive haemagglutination inhibition was performed to check the comparative efficacy of Active and Passive haemagglutination inhibition. In passive haemagglutination inhibition tanned sensitized cells remains effective due to their long effective life when stored at 4̊c and its makes an ideal test for diagnosis of PPR. Newly developed assays were compared against cELISA for PPR using kappa statistics and diagnostic sensitivity and specificity were determined.
The results of both assays were compared with results of competitive enzyme linked immunosorbent assay. In this study cELISA was considered as golden standard. The relative sensitivity and specificity of Active haemagglutination inhibition is 94.9% and 97.9% respectively. (Kappa 0.9264). However the sensitivity and specificity of Passive haemagglutination inhibition is 91.1% and 95.0% respectively.(kappa 0.8595). This study describes the serological detection of PPR virus by Active haemagglutination and passive haemagglutination inhibition (HI and PHA respectively). It was also concluded the comparative efficacy of (PHA and HI) that Active haemagglutination inhibition is more reliable technique than passive haemagglutination inhibition assay for the diagnosis of PPR disease in small ruminants (sheep and goats).