Type I Interferons and Their Role in Maternal Recognition of Pregnancy and Fecundity in Domestic Ruminant Species

This chapter discusses the role played by type I interferons (IFN) in maternal recognition of pregnancy in the large domestic farm species. The initial phenomenon of corpus luteum rescue, however, is one aspect of the phenomenon known as maternal recognition of pregnancy. The factors released by ovine and bovine conceptuses that were the prime candidates as the anti-luteolysins were identified as a group of low molecular weight proteins that were first secreted in abundance around the critical time when maternal recognition of pregnancy was known to occur. The mixture of IFN- τ, purified from medium in which conceptuses had been cultured is able to extend estrous cycle length when provided to cattle and sheep in the critical period of maternal recognition of pregnancy. Conformational analysis suggests that the IFN-τ also probably have structures quite similar to those of other type I IFN. However, there is evidence that the IFN-τ may differ subtly from IFN- α in some of their properties.