Type I interferon genes from the egg-laying mammal, Tachyglossus aculeatus (short-beaked echidna)

Gavan Harrison, Kelly McNicol, Elizabeth Deane

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

The type I IFN are an important group of multifunctional cytokines that have, for whatever reason, evolved to a high level of complexity in eutherian mammals such as humans and mice. However, until recently, little was known about the type I IFN systems of the other two groups of extant mammals, the marsupials and the egglaying monotremes. Preliminary partial type I IFN sequences from the short-beaked echidna were previously found to cluster only with the IFN-β subtype in phylogenetic analyses, but a lack of sequence information made interpretation of these results tenuous. Here, we report cloning of the full-length genes of representatives from the two previously defined groups of echidna type I IFN by genomic walking PCR. Along with analysis of conserved cysteine placement and promoter elements, phylogenetic analysis incorporating these sequences strongly suggest that the two groups of echidna type I IFN genes are in fact homologueous to IFN-α and IFN-β, confirming that the duplication leading to these two major classes of type I IFN occurred prior to the divergence of eutherians and monotremes some 180 million years ago. Thus, even though there are major differences in gene copy number and heterogeneity, separate IFN-α and IFN-β gene families are a feature of the cytokine networks of all three groups of living mammals.
Original languageEnglish
Pages (from-to)112-118
Number of pages7
JournalImmunology and Cell Biology
Volume82
Issue number2
DOIs
Publication statusPublished - 2004

Keywords

  • Echidna
  • Evolution
  • IFN
  • Monotreme
  • Type I interferon

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