A positive association between resistance to ovine footrot and particular lymphocyte antigen types.
The distribution of 12 Class I ovine lymphocyte antigens (OLA) was examined in 4 flocks of sheep vaccinated against and/or challenged with Bacteroides nodosus, the transmitting agent of footrot. In a flock of 47 Corriedales in New Zealand, which had been specially bred for resistance to footrot, a higher frequency (70.2%) of OLA type SY6 was found compared with 42.9% in 49 unselected Corriedale sheep (P = 0.001). The serum antibody response of 12 selected Corriedale ewes was compared with that of 12 unselected ewes of the same age after vaccination with a multivalent footrot vaccine and the selected ewes had significantly (P = 0.01) higher agglutinin titres than the unselected ewes, 7 weeks after vaccination. In 3 trials involving 108, 120 and 135 Australian Merinos in Victoria, SYlb was associated with a reduction in the number of feet affected with severe footrot (P = 0.05, P = 0.01, P = 0.02) and in 2 of the trials there was a relationship between SY6 and high vaccinal agglutinin titres. This SY6 effect was evident in the first trial 31 days after primary vaccination (P = 0.05) and again 20 days later after secondary vaccination (P = 0.01). In the second trial, when the sheep were vaccinated 49 days after challenge, an association was again found between SY6 and high agglutinin titres (P = 0.05) after primary but not after secondary vaccination. Exposure of 157 vaccinated Merino rams to B. nodosus during a footrot outbreak in New South Wales also showed an association between low infection and SY6 and SYlb.(ABSTRACT TRUNCATED AT 250 WORDS)
Outteridge
P M
PM
CSIRO, Division of Animal Health, New South Wales.
Stewart
D J
DJ
Skerman
T M
TM
Dufty
J H
JH
Egerton
J R
JR
Ferrier
G
G
Marshall
D J
DJ
D000818:Animals; D000907:Antibodies, Bacterial / Q000032:analysis; D001428:Bacterial Vaccines / Q000276:immunology; D001439:Bacteroides / Q000276:immunology; D005260:Female; D005535:Foot Rot / Q000276:immunology* / Q000517:prevention & control; D015395:Histocompatibility Antigens Class I / Q000032:analysis*; D007113:Immunity, Innate; D008214:Lymphocytes / Q000276:immunology*; D008297:Male; D009520:New Zealand; D012756:Sheep / Q000276:immunology; D012757:Sheep Diseases / Q000276:immunology* / Q000517:prevention & control
D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; D015395:Histocompatibility Antigens Class I