title: The infectivity and antigenicity of Toxocara canis eggs can be retained after long-term preservation.
abstract: Suspensions of fertilized eggs of Toxocara canis were mixed with 2% neutral formalin and preserved at 4 degrees C. When, after storage for 0, 12, 18, 21 and 24 months, samples of the eggs were incubated at 30 degrees C for 12 days, 96.8%, 92.6%, 74.1%, 51.0% and 19.3% of the eggs in the samples were found to embryonate. The embryonated eggs produced from the fertilized eggs preserved (in 2% neutral formalin at 4 degrees C) for 0, 12, 18 and 21 months were then tested for their infectivity to BALB/c mice, each mouse being given 800 embryonated eggs. The numbers of larvae recovered from the mice and the sites from which they were recovered, 2 or 14 days post-infection, appeared unaffected by the length of storage of the eggs. The infected mice all had similar eosinophil counts in their peripheral blood and similar serum titres of Toxocara-specific IgM and IgG antibodies, and cultures of their spleen cells produced similar amounts of interleukin-4, interleukin-5 and interferon-gamma when stimulated with concanavalin A. The results of SDS-PAGE indicated that egg preservation for at least 21 months had no effect on the excretory-secretory antigens in samples of medium from cultures of infective larvae released from the eggs. In summary, at least 50% of the fertilized eggs preserved in 2% neutral formalin at 4 degrees C for 21 months could fully embryonate and then had the same infectivity and antigenicity as embryonated fresh eggs.
authors.affiliation: Department of Parasitology, Kaohsiung Medical University, No. 100, Shih-Chuan 1st Road, Kaohsiung, Taiwan.
authors.forename: L-Y
authors.initials: LY
authors.lastname: Chung
authors.forename: B-H
authors.initials: BH
authors.lastname: Fang
authors.forename: J-H
authors.initials: JH
authors.lastname: Chang
authors.forename: S-M
authors.initials: SM
authors.lastname: Chye
authors.forename: C-M
authors.initials: CM
authors.lastname: Yen
mesh_terms: D000818:Animals; D000909:Antibodies, Helminth / Q000096:biosynthesis; D000947:Antigens, Helminth / Q000276:immunology*; D016207:Cytokines / Q000096:biosynthesis; D004591:Electrophoresis, Polyacrylamide Gel; D004804:Eosinophils / Q000473:pathology; D005557:Formaldehyde; D007814:Larva / Q000254:growth & development; D007958:Leukocyte Count; D008099:Liver / Q000469:parasitology; D051379:Mice; D008807:Mice, Inbred BALB C; D011309:Preservation, Biological / Q000379:methods*; D017166:Toxocara canis / Q000254:growth & development / Q000276:immunology / Q000472:pathogenicity*; D014120:Toxocariasis / Q000276:immunology / Q000469:parasitology*; D015053:Zygote / Q000254:growth & development
chemical_list: D000909:Antibodies, Helminth; D000947:Antigens, Helminth; D016207:Cytokines; D005557:Formaldehyde