logicp_writings/new/mRNA_Covid.md

Introduction

Overview

Update on the current state of evidence RE mRNA lipid nanoparticle vaccines

• how they distribute
• how long they persist
• how long they are expressed
• what this all leads to

Early Reports

• January 2020 - antibodies to detect Nucleocaspid protein of SARS-CoV-2 Usually takes a while (supposedly had come into existence or had been isolated in the beginning of 2020 (Corman Drosten PCR) to produce a nucleocaspid antigen in some form (PCR and express it in some cells), immunize animals, extract antibodies from those animals to use this antibody in immunohistochemistry
• 2006 (also RT-PCT assay of SARS-CoV-2)

Distribution

A study which Pfizer submitted to regulatory authorities which came out into the open through Japanese regulators. Pfizer used a model protein (Luciferase) in place of SARS-CoV-2 S protein. Lipids made radioactive.

• Injected rats

• Follow marked lipids

  Results

  Rapidly, the vaccine shows up in the blood plasma (15 minutes onward). After injection, there is a measurable level in the blood plasma which peaks for 2 hours and concomitantly the labelled vaccine accumulates in various organs:

  • high levels in the liver and spleen
  • Also in the ovaries and adrenal glands
  • Testes
  • Levels were still increasing in some organs at extent of this (no idea what peak would be)

Questions

How can we understand this particular pattern of distribution between different organs. Will discuss in details how the lipid nanoparticles are supposed to work

Details

• Mixture of 4 different lipids
• wrap modRNA (chemically modified mRNA - more stable - proline mutations)
• Ionizable lipid which at proper pH is cationic which wraps the negatively charged mRNA
• 2 naturally-occurring (cholesterol and phosphatidylcholine) stabilize structure of lipid nanoparticle
• Surface has Polyethylene glycol-linked lipid
  • Gives particle and overall hydrophilic / water-soluble characteristic
• Cholesterol leaks out from this particles, meaning they are no very stale. Cholesterol leaves and crystallizes on its own (this modifies the activity of these particles)

Molecular Structures

2 major synthetic lipids (ALC for Pfizer vaccines, for example)

• In both cases we have 2 acetyl chains (aklyl chains in one case) with 14 carbons
  • This length judiciously chosen: enables lipids to loosely attach with LNPs, which affects in-vivo behaviour

Loose Lipids

In a nutshell, PEGylated lipids are replaced with something from the subject, such as cholesterol

• Pegylated lipids desorb from the particle, exposing less H2O-soluble lipids underneath
• Stabilize by binding with protein
  • Apolipoprotein (wraps lipid transport particles - lipoproteins)
  • Other proteins: Ab and complement proteins

Apolipoproteins

Q. What is the function of these particles? A. Mediate the transport of lipoproteins or, in this case, LNPs into cells and in across cell barriers

• Produced in liver and small intestine
• Overcomes cellular behaviour in blood vessels using transcytosis
  • Cells receptors recognize apolipoproteins
  • Release particles on the tissue side

What This Means

Biomolecular Corona

• LNPs will accumulate in organs which allow apolipoprotein
  • Liver (produces)
  • Endocrine glands (cholesterol used as precursor for hormone synthesis)
  • Placenta accumulates for progestin production and to supply lipoprotein to fetus
  • Lactating breast glands acquire fat/cholesterol from lipoproteins Also expect spleen/lymphatic organs to accumulate LNP

Intracellular Fate of mRNA/LNP

• Endocytosis (perhaps via apolipoprotein receptor)
• Endosome (vessicle encasing the particle) is acidified