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Investigation of a Possible Link Between Vaccination and the 2010 Sheep Pox Epizootic in M orocco
Author(s) -
Haegeman A.,
Zro K.,
Sammin D.,
Vandenbussche F.,
Ennaji M. M.,
De Clercq K.
Publication year - 2016
Publication title -
transboundary and emerging diseases
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.392
H-Index - 63
eISSN - 1865-1682
pISSN - 1865-1674
DOI - 10.1111/tbed.12342
Subject(s) - epizootic , virology , outbreak , biology , vaccination , strain (injury) , phylogenetic tree , attenuated vaccine , genotype , veterinary medicine , virulence , medicine , genetics , gene , anatomy
Summary Sheep pox is endemic in most parts of N orthern A frica and has the potential to cause severe economic problems. Live attenuated vaccines are used in M orocco, and in many other countries, to control the disease. Sheep pox virus ( SPPV ) re‐appeared in 2010 causing a nodular clinical form previously not observed in M orocco. The severe clinical signs observed during the course of this outbreak and initial reports citing similarity in nucleotide sequence between the M oroccan vaccine strain and field isolates warranted a more in depth analysis of this epizootic. In this study, sequence analysis showed that isolates obtained from four provinces of eastern M orocco were identical, demonstrating that a single SPPV strain was responsible for the 2010 epizootic. In addition, the genome fragments sequenced and phylogenetic analyses undertaken as part of this study showed significant differences between field isolates and the M oroccan vaccine strain. New PCR methods were developed to differentiate between wild‐type isolates and vaccine strains of SPPV . Using these methods, no trace of wild‐type SPPV was found in the vaccine and no evidence was found to suggest that the vaccine strain was causing clinical disease.