Abstract
The contents of toxoplasma antibodies were estimated by a micro-modification of the dye test for up to 3 years after the initial stage of infection both in ewes which had aborted and in ewes with normal pregnancies. During the first 2 years the titres in ewes which had aborted were significantly higher than in ewes with normal pregnancies. The investigation indicated that dye test titres ≥ 1/512 usually occur during the first stage of infection, and are mainly found in ewes with clinical toxoplasmosis.
The dye test titres in lambs due to antibodies transferred with the colostrum were up to 4 twofold dilutions higher than in their dams during the first 2 days after birth. Later the titres declined, and at the age of about 2 months only 3 of 29 lambs had higher titres than their dams. After the age of about 3 months maternally derived antibodies were not detected.
The contents of toxoplasma antibodies in sheep with listeric encephalitis were nearly the same as found by a serological survey of the local sheep population. The examination indicated that the dye test titres in sheep are little influenced by conditions that may affect the defence mechanism.
Sheep with haemoglobin type B had significantly higher dye test titres than sheep with the haemoglobin types A and AB when examined less than about 6 months after they had acquired the infection. No association was found between the susceptibility to toxoplasma infection and the haemoglobin type. kw|Keywords|k]toxoplasma infection; k]antibody formation; k]sheep {fn1|This work was supported by grants from The Norwegian Research Council for Science and for the Humanities.}
Sammendrag
Serumprøver fra sauer som hadde abortert på grunn av toxoplas- mose, og fra sauer med normal drektighet, ble undersøkt ved hjelp av en mikromodifikasjon av Sabin & Feldman’s dye test i opp til 3 år etter at de var blitt infiserte. De første 2 årene var det signifikant høyere titre hos sauer som hadde abortert, sammenliknet med sauer med normal drektighet. Undersøkelsen tydet på at titre ≥ 1/512 ervanligst på et tidlig Stadium av infeksjonsforløpet i forbindelse med klinisk toxoplasmose.
Dye test titrene hos lam etter overføring av antistoff med kolo- strum var opp til 4 doble fortynninger høyere enn hos morsøyene de fprste 2 dagene etter fødselen. Senere fait titerverdiene gradvis, og ved ca. 2 måneders alderen hadde bare 3 av 29 lam høyere titre enn morsøyene. Etter ca. 3 måneders alderen ble det ikke påvist over- førte antistoff.
Titerverdiene hos sau med listeria-encephalitt var omirent som påvist ved serologisk undersøkelse av den friske sauepopulasjon innen samme område. Undersøkelsen tydet på at dye test titre hos sau er lite påvirket av forhold som kan ha betydning for sjukdomsresistensen.
Sau med hemoglobintype B hadde signifikant høyere titre enn sau med hemoglobintypene A eller AB ved undersøkelse innen 6 må- neder etter at de ble infiserte. Det ble ikke funnet noen sammenheng mellom mottakelighet for infeksjonen og hemoglobintype.
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