Title page for ETD etd-05042001-080834


Type of Document Master's Thesis
Author Cook, Anne Grimsley
Author's Email Address ancook2@vt.edu
URN etd-05042001-080834
Title Interpretation of the Detection of Antibodies to Sarcocystis neurona in the serum and CSF of young horses
Degree Master of Science
Department Veterinary Medical Sciences
Advisory Committee
Advisor Name Title
Buechner-Maxwell, Virginia A. Committee Chair
Dascanio, John J. Committee Member
Lindsay, David S. Committee Member
Parker, Nikola A. Committee Member
Schurig, Gerhardt G. Committee Member
Keywords
  • western blot
  • immunoglobulins
  • neonate
  • equine protozoal myeloencephalits
  • cerebrospinal fluid
  • Sarcocystis neurona
  • horse
  • passive transfer
Date of Defense 2001-04-19
Availability unrestricted
Abstract
Horses that are exposed to Sarcocystis neurona, a causative agent of equine protozoal myeloencephalitis, produce antibodies that are detectable in serum by western blot (WB). A positive test is indicative of exposure to the organism. Positive tests in young horses can be complicated by the presence of maternal antibodies. Passive transfer of maternal antibodies to S. neurona from seropositive mares to their foals was evaluated. Foals were sampled at birth (presuckle), at 24 hours of age (postsuckle), and at monthly intervals. All foals sampled before suckling were seronegative. Thirty-three foals from 33 seropositive mares became seropositive with colostrum ingestion at 24 hours of age, confirming that passive transfer of S. neurona maternal antibodies occurs. Thirty-one of the 33 foals became seronegative by 9 months of age, with a mean seronegative conversion time of 4.2 months. These results indicate that evaluation of exposure to S. neurona by WB analysis of serum may be misleading in young horses.

Cerebrospinal fluid (CSF) samples from 15 neonatal (2-8 day) foals were examined for the presence of antibodies to S. neurona by WB analysis. Twelve of 13 foals that were seropositive were also CSF positive, suggesting that maternal antibodies to S. neurona cross the blood-CSF barrier in neonatal foals resulting in a positive CSF WB. Repeat taps were performed on 5 of the foals which showed that the immunoreactivity of the western blot decreases over time. Two of the 5 foals were CSF negative at 83 and 84 days of age, with 1 foal still positive at 90 days, and 2 foals positive at 62 days. These results indicate that maternal antibodies to S. neurona in the CSF can confound WB results in neonatal foals up to several months of age.

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