Interferon-delta: the first member of a novel type I interferon family.
We have recently described a novel type I interferon (IFN) co-expressed with IFN-gamma by the trophectoderm of the pig conceptus between day 12 and day 18 of gestation, a development stage that corresponds to implantation in the uterus. This IFN, now officially named IFN-delta, is recognized as the first member of a novel type I IFN family. This paper reviews the main published data on IFN-delta, together with some new data, showing that IFN-delta, while being a true type I IFN, has some very specific structural and biological properties. Sequences related to IFN-delta coding sequence were found in the genome of man and other ungulates but the only other potentially functional gene was found, so far, in the horse. The pig IFN-delta mature protein, with 149 amino acids, is the smallest of all known type I IFNs. It is unusually rich in cysteines (seven residues), and has a very basic isoelectric point. Recombinant IFN-delta expressed in insect cells is glycosylated and has a high antiviral activity on porcine cells, but not on human cells. It has high antiproliferative activity, which is significantly enhanced in the presence of IFN-gamma. This new IFN was shown to bind on pig cells to the same type I receptor as IFN-alpha. IFN-delta and IFN-gamma genes are co-regulated in the pig trophectoderm, whose cells on day 14-16 of development simultaneously secrete both IFN proteins. The biological role of porcine IFN-delta in early pregnancy has been found unrelated to the known antiluteolytic effect of trophoblastic IFN-tau in ruminants.
Lefèvre
F
F
Unité de Virologie et Immunologie Moléculaires, Inra, Jouy-En-Josas, France.
Guillomot
M
M
D'Andréa
S
S
Battegay
S
S
La Bonnardière
C
C
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D007370:Interferon Type I / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D007371:Interferon-gamma; D008969:Molecular Sequence Data; D017471:Receptors, Interferon / Q000378:metabolism; D013552:Swine
D007370:Interferon Type I; D017471:Receptors, Interferon; C037655:interferon, delta; D007371:Interferon-gamma