Effect of passive transfer of maternal immune components on infection with ovine herpesvirus 2 in lambs.
OBJECTIVE
To define the role of passively tranferred immunity in protection against early infection with ovine herpesvirus 2 (OvHV-2) in lambs.


METHODS
15 adult sheep and 34 lambs.


METHODS
2 groups of animals were used, including 15 lambs born to OvHV-2-free ewes and 19 lambs born to OvHV-2-positive ewes. After nursing colostrum, all lambs and their dams were introduced into a flock positive for OvHV-2. Blood was obtained from the lambs every 2 weeks and examined by PCR assay and competitive inhibition ELISA.


RESULTS
None of the animals had positive results by PCR analysis for samples obtained approximately 2 weeks after introduction into the flock. In the group of lambs from OvHV-2-infected ewes, 5 of 19 had positive results at 1 month of age and 17 of 19 by 5 months of age. In the group of offspring from OvHV-2-negative ewes, only 1 of 15 had positive results at 1 month of age, and the number reached 12 of 15 by 5 months of age. All lambs in both groups had positive results by 6 months. An active antibody response to the virus was detected in animals within 3 weeks after viral DNA became detectable in the blood.


CONCLUSIONS
Analysis suggests that passively transferred immunity does not play an important role in the delay of infection with OvHV-2 in lambs. Age also does not seem to influence susceptibility. The rate of infection in young lambs may simply be a reflection of the intensity of viral exposure in their environment.
Li
Hong
H
Animal Diseases Research Unit, USDA-Agricultural Research Service, Pullman, WA 99164, USA.
Snowder
Gary D
GD
Crawford
Timothy B
TB
D000818:Animals; D000831:Animals, Newborn; D000914:Antibodies, Viral / Q000097:blood; D003126:Colostrum / Q000378:metabolism; D004279:DNA, Viral / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D006564:Herpesviridae / Q000235:genetics / Q000276:immunology*; D006566:Herpesviridae Infections / Q000097:blood / Q000276:immunology* / Q000662:veterinary* / Q000821:virology; D007112:Immunity, Maternally-Acquired / Q000276:immunology*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012757:Sheep Diseases / Q000276:immunology* / Q000821:virology; D034561:Sheep, Domestic; D013047:Specific Pathogen-Free Organisms
D000914:Antibodies, Viral; D004279:DNA, Viral