Evaluation of homologous and heterologous protection induced by a virulent field strain of orf virus and an orf vaccine in goats.
OBJECTIVE
To evaluate cross protection provided by administration of contagious ecthyma vaccines against strains of orf virus in goats.


METHODS
126 Boer-Spanish crossbred goats (3 to 20 days old).


METHODS
85 goats were vaccinated with a goat-derived contagious ecthyma vaccine. Of these, 41 were challenge exposed with the virus strain for the contagious ecthyma vaccine, 40 were challenge exposed with a more virulent field strain of orf virus, and 4 were lost to predation or died. Another 41 goats were vaccinated with a vaccine produced from a more virulent field strain of orf virus; of these, 18 were challenge exposed with the virus strain of the goat-derived contagious ecthyma vaccine, 18 were challenge exposed with the more virulent field strain of orf virus, and 5 were lost to predation or died.


RESULTS
Vaccination with the goat-derived contagious ecthyma vaccine did not significantly reduce the number of goats with lesions or lesion severity caused by challenge exposure with the more virulent field strain of orf virus. Vaccination with the vaccine produced from the more virulent field strain of orf virus significantly reduced the number of goats with lesions attributable to challenge exposure with the virus strain of the goat-derived contagious ecthyma vaccine, but it failed to significantly reduce lesion severity.


CONCLUSIONS
Vaccination did not result in cross protection for the 2 strains of orf virus. This may have been attributable to antigenic differences and may be a factor in outbreaks of contagious ecthyma in vaccinated goats.
Department of Veterinary Pathobiology, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843, USA. jmusser@cvm.tamu.edu
Jeffrey M B
JM
Musser
Daniel F
DF
Waldron
Charles A
CA
Taylor
D000367:Age Factors; D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D004474:Ecthyma, Contagious / Q000276:immunology / Q000473:pathology / Q000517:prevention & control* / Q000821:virology; D015511:Goat Diseases / Q000276:immunology / Q000473:pathology / Q000517:prevention & control* / Q000821:virology; D006041:Goats; D009923:Orf virus; D011897:Random Allocation; D013045:Species Specificity; D014765:Viral Vaccines / Q000008:administration & dosage / Q000276:immunology* / Q000627:therapeutic use
D000914:Antibodies, Viral; D014765:Viral Vaccines