Compositions and methods for early pregnancy diagnosis

Abstract

Pregnancy-associated glycoproteins (PAGs) are structurally related to the pepsins, thought to be restricted to the hoofed (ungulate) mammals and characterized by being expressed specifically in the outer epithelial cell layer (chorion / trophectoderm) of the placenta. By cloning expressed genes from ovine and bovine placental cDNA libraries, the inventors estimate that cattle, sheep, and most probably all ruminant Artiodactyla, possess possibly 100 or more PAG genes, many of which are placentally expressed. The PAGs are highly diverse in sequence, with regions of hypervariability confined largely to surface-exposed loops. Selected PAG that are products of the i0nvasive binucleate cells, expressed highly in early pregnancy at the time of trophoblast invasion and expressed weakly, if at all, in late gestation are useful in the early diagnosis of pregnancy. In a preferred embodiment, the invention relates to immunoassays for detecting these PAGs.

Description

BACKGROUND OF THE INVENTION [0001] This application claims priority to U.S. Provisional Application Ser. No. 60 / 078,783 filed Mar. 20, 1998 and U.S. Provisional Application Ser. No. 60 / 106,188 filed Oct. 28, 1998. The entire text of each of the above-referenced disclosures is specifically incorporated by reference herein without disclaimer. The government may own rights in the present invention pursuant to grant R37 HD29483 and USDA grant 9601842. [0002] I. Field of the Invention [0003] The present invention relates generally to the fields of veterinary medicine, reproductive biology and diagnostics. More specifically, the present invention relates to the use of analytical methods to detect early stage pregnancy. [0004] II. Related Art [0005] Pregnancy diagnosis is an important component in sound reproductive management, particularly in the dairy industry (Oltenacu et al., 1990) where a high proportion of artificial inseminations fail (Streenan and Diskin, 1986). A reliable yet simp...

AI Technical Summary

Benefits of technology

[0009] Therefore, it is an objective of the present invention to provide a sensitive and accurate test for early pregnancy. Using a selected boPAG as the biochemical marker, the present invention provides an early pregnancy test in which the PAG antigen a) is produced abundantly in early, and preferably not in late, pregnancy, b) is a product of the binucleate cell, and absent or not present in significant amounts postpartum, and c) minimally cross-reacts with late PAG products that might persist in maternal serum during the post-partum interval. The early immunoassay will be particularly useful in the dairy industry where animals are usually confined for at least part of the day and where intensive management is practiced. A modified test also is likely to have value in captive breeding programs for other animals, e.g., for the ruminants okapi or giraffe and possibly for other non-ruminant species.

Problems solved by technology

Even though all the procedures are potentially useful, all have fallen short of expectations in terms of their practical, on-farm use.

For example, measurements of milk or serum progesterone around day 18-22 yield unacceptably high rates of false positives (Oltenacu et al., 1990; Markusfeld et al., 1990).

Ultrasonography has an advantage over rectal palpation in accuracy, particularly before day 45 (Beal et al., 1992; Cameron and Malmo, 1993), but the instrument is expensive, its use requires considerable training, and there is a finite risk to the animal.

First, it can detect pregnancy relatively early.

There remain, however, two major disadvantages to this procedure.

First, positive diagnosis in the fourth week of pregnancy remains somewhat uncertain because antigen concentrations in blood are low and somewhat variable.

Such delays are extremely costly and constitute a major economic loss to the industry.

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