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Abstract
6. Summary
Peste des petits ruminants (PPR), is an acute contagious disease caused by a Morbillivirus in the family paramyxoviridae. It affects small ruminants and occasionally wild animals. It occurs in Africa (South of the Sahara), the Arabian Peninsula, throughout most of the Middle Eastern countries, and south-west Asia. Vaccination has been carried out to control the disease using the rinderpest tissue culture vaccine, based on the principle that an antigenic relationship exists between PPR and rinderpest viruses. In 1998, the OIE International Committee endorsed the use of a homologous PPR vaccine in countries that have decided to follow the (OIE pathway) for epidemiological surveillance for rinderpest in order to avoid confusion when serological surveys are performed. This homologous vaccine was prepared through the attenuation of a hot wild PPR virus strain Known as (Nigerian 75/1).
Although severe or wide spread storms of PPR are not reported in Egypt; however, a locally isolated, identified and characterized PPR virus (Egypt-87) was attenuated through a number of consecutive passages on vero cells and a specific homologous PPR vaccine was and still being manufactured at the VSVRI for exportation to countries of the Arabian gulf area and some African countries.
Aiming at in-depth coverage of utilization aspects of this vaccine as well as broader elucidation of the response to vaccination and finding out some answers to the enquiries raised by veterinary authorities at the importing countries; the present studies were undertaken.
An experimental batch of this vaccine was produced and qualified as for sterility, identity, safety, potency and efficacy, based on standard operating procedures as well as good laboratory practices; thus, meeting international requirements. Seven groups of local breed sheep (naïve) at the age of 9-12 months were allotted to accomplish the studies presented. Seven routes of administration of the vaccine were tried, viz intranasal instillation, ocular instillation, oral, intralymphonodular (prescapular), intramuscular (thigh), intravenous (jugular) and subcutaneous (neck region). A vaccine dose of 3 log10 TCID50 was given per head of 5 animals in each of the seven groups. Two animals per group were held as an in-contact control given a placebo in correspondence. Keen clinical follow-up for several weeks post vaccination revealed the absence of even a single sign of ill-health, side effects or disease syndrome. The seven groups remained absolutely normal. Control contact animals remained naïve (seronegative to PPRV), while the seven vaccinated groups seroconverted; meaning that the PPR virus (attenuated) displayed no shedding any way.
Consequences of vaccination per 7 routes in seven groups were configurated as a resultant acquisition of a humoral immune response; evaluated by virus neutralization test, as a master test and an indirect ELISA test as an adjunct one. Monitoring of an induced cell-mediated immune response was evaluated by a lymphocyte transformation test as well as phagocytic assay tests (phagocytic index and phagocytic percentage). Results of monitoring of both humoral and cell-mediated immune responses were statistically analyzed.
Statistical analysis using ANOVA test revealed that differences through the seven groups were significant at P > 0.05 as for both geometric mean neutralizing antibody titres, ELISA results as well as result of the lymphocyte transformation test.
Differences through the seven groups were found to be insignificant as for the results of the phagocytic activity, both percentages and indices.
Detailed interpretations of the obtained results were found to be highly confirmed upon applying statistical analysis.