  The spike glycoprotein of the SARS-CoV-2 virus, which causes COVID-19, has
attracted attention for its vaccine potential and binding capacity to host cell
surface receptors. Much of this research focus has centered on the ectodomain
of the spike protein. The ectodomain is anchored to a transmembrane region,
followed by a cytoplasmic tail. Here we report a distant sequence similarity
between the cysteine-rich cytoplasmic tail of the coronavirus spike protein and
the hepcidin protein that is found in humans and other vertebrates. Hepcidin is
thought to be the key regulator of iron metabolism in humans. An implication of
this preliminary observation is to suggest a potential route of investigation
in the coronavirus research field making use of an already-established
literature on the interplay of local and systemic iron regulation,
cytokine-mediated inflammatory processes, respiratory infections and the
hepcidin protein. The question of possible homology and an evolutionary
connection between the viral spike protein and hepcidin is not assessed in this
report, but some scenarios for its study are discussed.
