Interferon production by the preimplantation sheep embryo

Area of Science:

• Reproductive immunology
• Virology
• Protein biochemistry

Background:

• Ovine trophoblast protein-1 (oTP-1) is secreted by sheep embryos during early pregnancy.
• oTP-1 is believed to mediate maternal recognition of pregnancy by maintaining corpus luteum function.
• Its amino acid sequence shows similarity to mammalian interferons-alpha (IFN-alpha) and it exhibits antiviral activity.

Purpose of the Study:

• To confirm that oTP-1 is a functional interferon.
• To characterize the antiviral activity and biological effects of purified oTP-1.
• To explore the role of oTP-1 as an IFN-alpha during early pregnancy.

Main Methods:

• Purification of oTP-1 from ovine conceptuses.
• Assessing antiviral activity using cytopathic effect inhibition assays in cell cultures (GBK-2 and A549 cells) challenged with various viruses.
• Neutralization assay using antiserum to human leukocyte IFN.
• Evaluating effects on cell growth and lymphocyte proliferation.

Main Results:

• Purified oTP-1 demonstrated significant antiviral activity against vesicular stomatitis virus and other viruses in cell culture.
• The specific antiviral activity of oTP-1 was determined to be 1.3 X 10(7) end point units/mg protein.
• Antiviral activity was neutralized by antiserum to human leukocyte IFN, supporting its classification as an IFN.
• oTP-1 inhibited cell growth and suppressed mitogen-stimulated lymphocyte proliferation, similar to human IFN-alpha.

Conclusions:

• Ovine trophoblast protein-1 (oTP-1) is confirmed as a functional interferon with significant antiviral properties.
• oTP-1 likely functions as an IFN-alpha during early sheep pregnancy, contributing to maternal recognition of pregnancy.
• The findings provide insights into the molecular mechanisms underlying pregnancy maintenance in sheep.