Detection of fetal twins in sheep using a radioimmunoassay for pregnancy-specific protein B1

Abstract

Ovine pregnancy-specific protein B (oPSPB) was isolated from sheep placentas. Antiserum to oPSPB was developed in rabbits. A quantitative RIA was developed and used to assay the serum concentrations of oPSPB during and after pregnancy in ewes bearing single or twin fetuses. Suffolk and Panama ewes, kept with rams equipped with a marking harness, were checked daily for breeding marks as an indication of estrus and bled daily between 10 and 30 d after marking. Ovine PSPB became detectable at 19.7 +/- .14 (mean +/- SE) d after breeding and increased steadily to d 30. Panama oPSPB concentration increased at a greater rate than that of Suffolks (breed x day interaction, P < .01). Ten ewes were bled twice weekly 3 wk before their expected date of lambing and weekly for 7 wk postpartum. Serum concentrations differed considerably between prepartum ewes, but concentrations remained stable within the period of 20 d prepartum. Following parturition, oPSPB concentrations dropped rapidly. In nine ewes, oPSPB was last detectable at 12.78 +/- 2.26 (mean +/- SE) d postpartum. In the 10th ewe, oPSPB was .65 ng/mL at the last sample on d 46 postpartum. To determine the effect of fetal number on oPSPB concentrations, ewes in which estrus was synchronized were bled at d 18, 25, 38, 60, 90, and 120 after breeding. Ewes were killed at d 60, 90, 120, and 148 and fetal number determined. There was a significant (P < .01) difference in the log of oPSPB concentrations according to number of fetuses, day postbreeding, and the day x fetal number interaction.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation and characterization of eight pregnancy-associated glycoproteins present at high levels in the ovine placenta between day 60 and day 100 of gestation

“…It was discussed in detail in our previous report [10], and in several earlier PAG purification attempts [6,7,9,17,23]. The large number of different molecules identified in our study may be due to the careful choice of our purification scheme.…”

“…These glycoproteins were later proven to be closely related to bovine PSPB (Pregnancy Specific Protein B) [4], isolated as early as 1982 by Butler et al [5]. In sheep, PAG called ovPAG [2], SBU-3 [6], or oPSPB [7] were identified mainly by three different approaches. In 1993, Atkinson et al [6] used a monoclonal antibody (anti-SBU-3) recognizing a placenta-specific carbohydrate epitope [8] to immunopurify placental antigens from placentomes of pregnant sheep uteri at various stages of gestation.…”

Litter-size-dependent intrauterine growth restriction in sheep

“…Maternal plasma PAG level increases with an increase in foetal number, and this foetal-number effect is evident at as early as 25 days of gestation (Willard et al, 1995;Ranilla et al, 1997;Vandaele et al, 2005). Use of PAG serum levels to predict litter size based on PAG concentration in early gestation was found to not be useful ( Vandaele et al, 2005).…”

Biodiversity of multiple Pregnancy-Associated Glycoprotein (PAG) family: gene cloning and chorionic protein purification in domestic and wild eutherians (Placentalia) – a review

“…The concentration of circulating PAGs depends on the number of well-being embryos/foetuses, and is higher in females with multiple than single pregnancies, according to the greater mass of the chorionic membranes in animals bearing twins [4, 70,98,99,117,118]. The secretion of PAGs can also differ based on the sex and breed of the foetus.…”

“…The presence of PAGs can be measured by radioimmunologic (RIA) and immunoenzymatic (ELISA) tests. These PAG tests allow for early pregnancy diagnoses in domestic cattle [69,80,91,[95][96][97][98], sheep [70,[99][100][101][102][103][104] and goats [105,106]. Moreover, heterologous PAG tests were also useful for pregnancy diagnoses in wild ruminants, i.e.…”