title: The immune response of foals to natural infection with equid herpesvirus-2 and its association with febrile illness.
abstract: Equid herpesvirus-2 (EHV-2) infection is ubiquitous in horses. Although EHV-2 infection has been associated with several disease syndromes, its true pathogenic significance in horses remains uncertain. Epstein-Barr virus (EBV), another gammaherpesvirus, has been shown to cause febrile illness in humans related to its immunopathologic effects. Thus, the purpose of this study was to describe the ontogeny of the immune response of a cohort of 9 foals to natural infection with EHV-2 by evaluating serial complete blood counts, lymphocyte morphology, cytokine gene expression in peripheral blood mononuclear cells (PBMC), viral load in nasal swabs and blood, and antigen-specific cellular immune responses of PBMC, in conjunction with clinical evaluation of the foals. The occurrence of fever in foals was not related to lymphocytosis or specific changes in lymphocyte morphology, cytokine gene expression, or viral load, but tended to be associated (P</=0.10) with increased EHV-2-specific responsiveness of PBMC. These results support the conclusion that the cellular immune response to EHV-2 may lead to an immunologically mediated disease of foals that is analogous to infectious mononucleosis caused by EBV infection in humans.
authors.affiliation: Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Brault
authors.forename: Myra T
authors.initials: MT
authors.lastname: Blanchard
authors.forename: Ian A
authors.initials: IA
authors.lastname: Gardner
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Stott
authors.forename: Nicola
authors.initials: N
authors.lastname: Pusterla
authors.forename: Samantha M
authors.initials: SM
authors.lastname: Mapes
authors.forename: William
authors.initials: W
authors.lastname: Vernau
authors.forename: Keith D
authors.initials: KD
authors.lastname: Dejong
authors.forename: N James
authors.initials: NJ
authors.lastname: Maclachlan
mesh_terms: D000818:Animals; D016207:Cytokines / Q000235:genetics; D005260:Female; D005334:Fever / Q000209:etiology / Q000662:veterinary*; D005434:Flow Cytometry; D006566:Herpesviridae Infections / Q000276:immunology / Q000662:veterinary*; D006734:Horse Diseases / Q000276:immunology*; D006736:Horses; D007371:Interferon-gamma / Q000096:biosynthesis; D007963:Leukocytes, Mononuclear / Q000821:virology; D008297:Male; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018144:Rhadinovirus
chemical_list: D016207:Cytokines; D007371:Interferon-gamma