Cross-Species Genome-Wide Analysis Reveals Molecular and Functional Diversity of the Unconventional Interferon-? Subtype

Shields, Lauren E.; Jennings, Jordan; Liu, Qinfang; Lee, Jinhwa; Ma, Wenjun; Blecha, Frank; Miller, Laura C.; Sang, Yongming

Both phylogenic and cluster analyses of cross-species IFN-ω molecules at protein levels imply that mammalian IFN-ω subtype was diverted from a common IFN ancestor gene during the evolution of reptiles or birds (2) . Even though mammalian IFNω subtype is similar to its IFN-α orthologs with regard to the antiviral or other biological activity, we show that its molecular origin may be closer to other common IFN subtypes such as IFN-ε/κ. After subtype-ramification, IFN-ω seems further diversify independently in different mammalian Family/Genus. However, cross-species analysis of IFN-ω sequence similarity at the protein level demonstrated that there are two general IFN-ω subgroups existing in such as moles, bats, shrews, and elephants, indicating IFN-ω molecules in these mammalian species might be derived from two close progenitors or further ramified along two directions (2, 41) . In contrast, IFN-ω molecules in pigs and cattle were generally clustered into one big cluster with several outliers presumably derived from a recent gene recombination event that may be catalyzed by some genetic repetitive elements as demonstrated in previous studies (Figure 4) (2, (8) (9) (10) .