PARENT SESSION

(T569) DETECTION OF INTERFERON- (IFN) BY ELISA IN OVINE PLASMA AND ITS RELATION TO PREGNANCY.

Lindemann, Cristina¹, Ewen, Morag¹, Alink, Frances¹, McEvoy, Tom¹, Rooke, John¹, ¹ Scottish Agricultural College, Aberdeen, Scotland

ABSTRACT- IFN is the signal for pregnancy recognition produced by the implanting blastocyst in ruminants. In vivo studies have shown that IFN secretion occurs between days 11 and 23 of gestation. The aims of this study were to determine whether plasma was immuno-positive for IFN, and whether plasma IFN at day 18 post AI was related to pregnancy status in sheep. Mature Scottish Blackface ewes (n=247) were artificially inseminated (laporoscopic AI, day 0) 48 h after progesterone (P4) releasing sponge removal. Plasma samples taken on day 18 (n=245) were used to determine pregnancy and analysed for IFN. Plasma samples obtained from a subset (n=48) of pregnant ewes on days 0 and 67 were also analysed for IFN. P4, determined by RIA, showed a bimodal pattern and <1.5 ng/ml was used to discriminate non-pregnant animals; IFN concentrations were determined by ELISA. There was a positive correlation between IFN and P4 concentrations at day 18 (r²=0.18, p<0.001). IFN concentrations (pg/ml, mean ±SD) at day 18 were greater (P<0.001) in pregnant (561±306, n=161) than in non-pregnant sheep (185±174, n=63). IFN was detected on both days 0 (63±44) and 67 (21±32) but concentrations were lower (p<0.001, paired t-test) than on day 18 (588±312); IFN concentrations were lower on day 67 than day 0 (P<0.001). IFN was therefore detected in plasma on day 18 after AI using an ELISA, and concentrations indicated pregnancy status. Variability in IFN concentrations however prevent their use as a diagnostic tool for pregnancy. In addition, low concentrations of IFN were detected in plasma when no implanting blastocyst was present in utero; the origins of this IFN remain to be established. SAC receives financial assistance from SEERAD.

KEY WORDS: Interferon-, Ovine, Pregnancy, Plasma