Experimental infection with Sarcocystis neurona alters the immune response: the effect on CD4+, CD8+, B-cell, monocyte and granulocyte populations in horses

Previous studies have demonstrated differences in CD4+, CD8+ and B-cell populations between EPM affected and normal horses. The overall goal of our project was to further define the immune deficiencies associated with S. neurona infection. We hypothesized that PMA/I stimulated suppression in EPM horses is due to decreased proliferation of monocytes, CD4+ and CD8+ cells. Our objectives were 1) to determine whether S. neurona infection causes an increase in apoptosis of a particular immune subset, and 2) to determine whether S. neurona causes a decrease in the number of cellular divisions (proliferation) of a particular immune cell subset. For this study, nine S. neurona antibody negative, immunocompetent horses were obtained. Baseline neurologic examinations, SnSAG1 (S. neurona Surface Antigen 1) ELISAs on cerebrospinal fluid (CSF) and serum, and baseline immune function assays were performed. Horses were randomly divided into groups. Five horses were challenged for ten days via intravenous injection of autologous lymphocytes infected with S. neurona. Neurologic parameters of all horses were assessed for 70 days following infection. Immune function was based on proliferation responses to mitogens, as assessed through thymidine incorporation. Enumeration of cellular subsets, degree of apoptosis and number of cellular divisions were assessed through flow cytometry. SnSAG1 ELISA of serum and CSF samples performed post-infection confirmed infection and disease. All infected horses displayed moderate neurologic signs on clinical examination. Some significant differences in cellular activities were noted. Additionally, this is the first time the method using S. neurona infected lymphocytes has been reproduced successfully by different investigators.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Veterinary Medical Sciences

Department dc:contributor.department

Veterinary Medical Sciences

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2009

Author dc:creator

• Lewis, Stephanie Rochelle

Chair dc:contributor.committeechair

• Witonsky, Sharon G.

Committee members dc:contributor.committeemember

• Lindsay, David S.
• Buechner-Maxwell, Virginia A.
• Dascanio, John J.
• Gogal, Robert M.

• Horse
• Equine Protozoal Myeloencephalitis
• EPM
• Sarcocystis neurona
• immune response
• lymphocyte proliferation assay

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-07072009-133935

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/33919