Detection Of Pregnancy-associated Glycoproteins Research Articles

The detection of Pregnancy Associated Glycoproteins in the blood Serum as an Indicator of Pregnancy in Bali Cattle

The detection of Pregnancy Associated Glycoproteins in the blood Serum as an Indicator of Pregnancy in Bali Cattle

Evaluation of pregnancy associated glycoproteins assays for on farm determination of pregnancy status in beef cattle.

Transrectal ultrasonography is known as the gold standard for pregnancy detection, but requires costly equipment and technical skills; therefore, access to an inexpensive and more user-friendly method with similar accuracy could benefit cattle producers. Detection of pregnancy-associated glycoproteins can accurately determine pregnancy in ruminants; however, usually requires specialized equipment for the assay. Thus, the objectives of these studies were to 1) validate the IDEXX Alertys OnFarm Pregnancy Test (lateral flow) and compare the accuracy of all three commercial PAG assays to transrectal ultrasonography and 2) to determine the postpartum interval necessary for clearance of pregnancy-associated glycoproteins from the previous pregnancy to avoid false positives. In study 1, blood samples from previously identified pregnant Bos taurus females from six different herds (nulliparous n = 1,205 and multiparous n = 1,539; samples collected between d 27 to 285 of gestation over a three-year period) were utilized. In study 2, postpartum females (primiparous n = 48 and multiparous n = 66) from one herd were utilized: (n = 1,066; samples collected weekly for up to 12 weeks postpartum). In study 1, level of agreement between different methods of pregnancy detection was determined by Pearson's correlation and Kappa scores. In study 2, data were analyzed as a repeated measure using the MIXED procedure of SAS with main effects of parity, days postpartum (dpp), and parity by days postpartum, then data were analyzed further using the REG procedure of SAS. In study 1, transrectal ultrasonography and lateral flow were positively correlated (r = 0.77; P <0.01), with 92.4% agreement. In study 2, the abundance of absorbance of PAGs rapidly decreased from 0 to 50 days postpartum, then continued to gradually decrease (P <0.01; r = 0.90). Prior to 42 days postpartum, PAG concentrations were sufficiently elevated resulting in false positive readings in all assays. In conclusion, there is very good agreement between transrectal ultrasonography and PAG assays, but likelihood of false positive results are highif assays are performed fewer than 42 days postpartum.

Evaluation of a bovine visual pregnancy test for the detection of pregnancy-associated glycoproteins in sheep.

As sheep produce similar pregnancy-associated glycoproteins (PAGs) to cattle, a commercially available bovine visual pregnancy test based on the detection of PAGs (visual-PAG-test) was evaluated in sheep. The test was performed with whole blood (WhB), plasma (P) and serum (S) of 163 pregnant and 153 non-pregnant ewes. Additionally, 11 pregnant ewes were tested weekly from day 14 to 49 of gestation and monthly from day 60 to day 149. Ten ewes were sampled weekly from the date of lambing until day 63 post-partum (p.p.). The sensitivity in mid-pregnancy (n=163) was 98.16% (WhB), 99.39% (P) and 99.39% (S) compared to transabdominal ultrasonography as the gold standard while the specificity (n=153) was 94.12% (WhB), 76.47% (P) and 93.46% (S), respectively. During early pregnancy, all 11 ewes were correctly identified as pregnant on day 42 (100%); however, the test sensitivity decreased to 54.6% (WhB) and 63.6% (S and P, respectively) at day 49. The ewes were again consistently identified as pregnant on day 63 (P) or on day 119 (S, WhB). The test was consistently negative from day 42 p.p. onwards in eight out of ten ewes. Two ewes remained consistently positive until the last sample on day 63 p.p. In conclusion, the test could be used to accurately select pregnant ewes at day 42 with a drop in sensitivity at day 49. The sensitivity of the visual-PAG-test was good in mid to late pregnancy, and early detection of pregnancy was possible in individual animals. In some ewes, the PAGs were however detectable for more than 63days p.p.-the previous breeding history should therefore always be taken into account for correct interpretation of the test results.

Diagnosis of pregnancy in Southern Lechwes (Kobus Leche) using a bovine assay for pregnancy-associated glycoprotein

Version:1.0 StartHTML:0000000206 EndHTML:0000004229 StartFragment:0000002452 EndFragment:0000004193 SourceURL:file://localhost/Volumes/NO%20NAME/000/Article%20PAG%20cobes%20final%202.1%20BL-CP-TR.doc Pregnancy diagnosis is an important part in reproduction management of wild ruminants involved in free-ranging and captive programs. The pregnancy-associated glycoproteins (PAGs) are a polymorphic family of placenta-expressed proteins, and released into maternal blood circulation where they can be assayed. These tests have been developed and validated in domestic species; PAGs have also been isolated in a few non domestic species of the Bovidae and Cervidae families. Assays have been used in many cervid species, but in very few wild Bovidae species,with high specificity. One hundred and twenty serum samples collected from 79 mature female Southern lechwes (Kobus leche) were tested using a commercial ELISA test (IDEXX Bovine Pregnancy Test Kit, IDEXX Europe BV, Hoofddorp, The Netherlands). Pregnancy was determined either at necropsy (n = 7), by transabdominal palpation in late pregnancy (n = 3), or by visualization of birth (n = 32). The other sera were controls from known non-pregnant females (n = 78). Following the range of use recommended by the manufacturer in domestic bovids, three false positive and two false negative results were identified; though this test gets the following values: sensitivity = 95.2%, specificity = 97.4%, positive predictive value = 95.2%, and negative predictive value = 97.4%. Using an ELISA validated in domestic species for the detection of PAGs appears to be a rapid, inexpensive and acurate test for pregnancy diagnosis in Southern lechwes. Nevertheless, more samples are needed to determine a better range of use of this test in this species.

The establishment of an ELISA for the detection of pregnancy-associated glycoproteins (PAGs) in the serum of pregnant cows and heifers

The pregnancy-associated glycoproteins (PAGs) are a large gene family expressed in trophoblast cells of ruminant ungulates. The detection of PAGs (more specifically, PAG-1) in maternal serum has served as the basis for pregnancy detection in cattle. Unfortunately, PAG-1 and/or antigenically-related PAGs exhibit a long half-life in maternal serum (>8 d) and can be detected 80–100 d post-partum, thereby producing false positives in animals bred within 60-d of calving. The goal of the present studies was to develop a monoclonal-based assay that targeted early-pregnancy PAGs whose persistence in maternal serum post-partum might be relatively short-lived. Three anti-PAG monoclonal antibodies that recognized distinct subsets of PAGs were selected and used as trapping reagents in a ‘sandwich’ type of enzyme-linked immunosorbant assay (ELISA). A polyclonal antiserum with broad specificity was used for detecting bound PAGs. A total of 42 cows and heifers were bled daily on day 15, days 22 to 28, and then weekly throughout pregnancy and for 10 weeks (∼70 d) into the post-partum period. The ELISA was able to detect PAG in maternal serum of all animals unambiguously by day 28 post-insemination (PAG concentration: 8.75 ± 3.04 ng/mL). In maternal serum, PAG concentrations peaked during the week of parturition at 588.9 ± 249.9 ng/mL, and after calving, PAG was completely cleared (half-life: 4.3 d) by eight-week post-partum in 38 of 40 of the animals tested and was at very low concentrations in the remaining two (1.4 and 4.9 ng/mL, respectively). In summary, a monoclonal-based assay has been established that is sensitive enough to detect PAG in maternal serum by the forth week of pregnancy, but does not suffer from carry-over of antigen from a previous pregnancy.