title: Pre-treatment with heat facilitates detection of antigen of Dirofilaria immitis in canine samples.
abstract: Diagnosis of Dirofilaria immitis infection in dogs is largely dependent on detection of antigen in canine serum, plasma, or whole blood, but antigen may be bound in immune complexes and thus not detected. To develop a model for antigen blocking, we mixed serum from a microfilaremic, antigen-positive dog with that of a hypergammaglobulinemic dog not currently infected with D. immitis and converted the positive sample to antigen-negative; detection of antigen was restored when the mixed sample was heat-treated, presumably due to disruption of antigen/antibody complexes. A blood sample was also evaluated from a dog that was microfilaremic and for which microfilariae were identified as D. immitis by morphologic examination. Antigen of D. immitis was not detected in this sample prior to heating but the sample was strongly positive after heat treatment of whole blood. Taken together, our results indicate that blood samples from some dogs may contain factors that inhibit detection of antigen of D. immitis, and that heat treatment of these samples prior to testing could improve the sensitivity of these assays in some patients.
authors.affiliation: Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, United States. Electronic address: susan.little@okstate.edu.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Little
authors.affiliation: Virginia-Regional College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, United States.
authors.forename: Candace
authors.initials: C
authors.lastname: Munzing
authors.affiliation: Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, United States.
authors.forename: Steph R
authors.initials: SR
authors.lastname: Heise
authors.affiliation: Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, United States.
authors.forename: Kelly E
authors.initials: KE
authors.lastname: Allen
authors.affiliation: Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, United States.
authors.forename: Lindsay A
authors.initials: LA
authors.lastname: Starkey
authors.affiliation: Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, United States.
authors.forename: Eileen M
authors.initials: EM
authors.lastname: Johnson
authors.affiliation: Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, United States.
authors.forename: James
authors.initials: J
authors.lastname: Meinkoth
authors.affiliation: Department of Veterinary Pathobiology, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, United States.
authors.forename: Mason V
authors.initials: MV
authors.lastname: Reichard
mesh_terms: D000818:Animals; D000947:Antigens, Helminth / Q000097:blood*; D004183:Dirofilaria immitis; D004184:Dirofilariasis / Q000175:diagnosis*; D004283:Dog Diseases / Q000175:diagnosis*; D004285:Dogs; D006358:Hot Temperature; D007118:Immunoassay / Q000662:veterinary; D010274:Parasitology / Q000331:legislation & jurisprudence*
chemical_list: D000947:Antigens, Helminth
keywords: Antigen test; Dirofilaria immitis; Dog; Heartworm; Heat treatment