title: Comparative study on three locally developed live orf virus vaccines for sheep in Saudi Arabia.
abstract: The epidemiology of orf virus infection in Saudi Arabia (SA) has been researched since 1990.  The results obtained during this period indicate that the disease is widespread, has great  economic impact and that no vaccine has been used against it. The present study compares the  immunogenicity and protective efficacy of three locally developed live orf virus vaccines. Two  of them differ in their passage history in Vero cell culture and the third was used as a virulent  virus in glycerine buffer. To the best of the authors' knowledge, no similar comparative study  has been conducted in the Middle East utilising three types of vaccines prepared from the  same virus strain. Selection of the candidate seed orf virus and performance of the quality  control tests were as laid out by the OIE for veterinary vaccine production. The vaccine seed  virus was a field orf virus isolated from a previous orf outbreak in Saudi Arabia. A simple  novel formula was developed to calculate the rate of reduction in the healing time (RHT %)  in the challenged sheep. This allowed direct comparison of the efficacy of the three types of  vaccines employed in the present study. The efficacy of each vaccine was tested on a cohort of  local Noemi sheep.
authors: College of Veterinary Medicine and Animal   Husbandry, King Faisal University. eabuelzein@yahoo.com.
authors: Fahdel M
authors: FM
authors: Housawi
authors: Eltayb M
authors: EM
authors: Abuelzein
authors: Ahmed A
authors: AA
authors: Gamee
authors: Adel I
authors: AI
authors: Alafaleq
mesh_terms: D000818:Animals; D002522:Chlorocebus aethiops; D004474:Ecthyma, Contagious / Q000453:epidemiology / Q000517:prevention & control*; D009923:Orf virus / Q000276:immunology*; D012529:Saudi Arabia / Q000453:epidemiology; D012756:Sheep; D016896:Treatment Outcome; D014611:Vaccination / Q000662:veterinary; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology; D014709:Vero Cells; D014765:Viral Vaccines / Q000008:administration & dosage / Q000276:immunology*
chemical_list: D014613:Vaccines, Attenuated; D014765:Viral Vaccines