The type I IFN of Bos taurus

Abstract

The Type I interferons (IFN) have major roles in the innate immune response to viruses, a function that is believed to have led to rapid expansion in the number and complexity of their genes. IFNT, which is a unique Type I IFN restricted to pecoran ruminants, also has a specialized role in maternal recognition of pregnancy in cattle. This work has two main aims 1) determine whether male and female blastocysts differ in the kind and number of IFNT they express and whether this pattern changes over development and 2) provide the first comprehensive annotation of the Type I IFN locus in Bos taurus, thereby providing an insight into the functional evolution of the Type IFN in ruminants. Data collected for the first aim indicate that female blastocysts do not transcribe a different set of IFNTs than males (p=0.54). However, significant differences (p < 0.001) were evident among conceptuses of different age, indicating that additional genes may be transcribed as IFNT production increases during development. The data collected for the second aim revealed the Type I IFN locus has undergone significant rearrangement and expansion in bovine compared to mouse and human. The IFNW subfamily is greatly expanded compared to other species, comprising 24 potentially functional genes. Selective pressure analysis found the regulatory regions of the IFNW are diverging faster than the coding regions. The identification of a new Type I IFN subfamily that is expressed from virally challenged bovine kidney cells is the most striking finding of the second aim.