Does the S1 (spike) protein of the COVID virus enter the brain, cross the blood-brain barrier (BBB)? Rhea's NATURE study on mice says YES! It is also taken up by the lung, spleen, kidney and liver
by Paul Alexander
I-S1 crosses the blood–brain barrier by adsorptive transcytosis and that murine angiotensin-converting enzyme 2 is involved in brain and lung uptake; also taken up by lung, spleen, kidney, liver
Just so you know the larger evidence landscape and that this was not studied by the vaccine makers nor mandated by the FDA. In short, we have no data to show us what are the implications of this.
‘It is unclear whether severe acute respiratory syndrome coronavirus 2, which causes coronavirus disease 2019, can enter the brain. Severe acute respiratory syndrome coronavirus 2 binds to cells via the S1 subunit of its spike protein. We show that intravenously injected radio-iodinated S1 (I-S1) readily crossed the blood–brain barrier in male mice, was taken up by brain regions and entered the parenchymal brain space. I-S1 was also taken up by the lung, spleen, kidney and liver. Intranasally administered I-S1 also entered the brain, although at levels roughly ten times lower than after intravenous administration. APOE genotype and sex did not affect whole-brain I-S1 uptake but had variable effects on uptake by the olfactory bulb, liver, spleen and kidney. I-S1 uptake in the hippocampus and olfactory bulb was reduced by lipopolysaccharide-induced inflammation. Mechanistic studies indicated that I-S1 crosses the blood–brain barrier by adsorptive transcytosis and that murine angiotensin-converting enzyme 2 is involved in brain and lung uptake, but not in kidney, liver or spleen uptake.’