https://twitter.com/vesselofspirit/status/123748864242514739...
According to the song lyric, "novel coronavirus / has a lipid outer shell". So it seems like some viruses have taken advantage of this.
Anyway, I think the important thing that the other commenter was saying is that mRNA needs to be carefully packaged to be medically useful. You can't inject pure RNA as a vaccine because not only is the mRNA going to be quickly degraded before it gets anywhere but if the immune system sees any RNA floating around by then it kicks itself into a frenzy because free-floating RNA is usually a sign that something nasty is afoot.
The envelopes used in an RNA vaccine are generally simpler, because they're working under different constraints than viruses. For example, their envelopes don't need to be easily manufactured in a cell.
But some RNA and DNA vaccines do use viruses as their delivery mechanisms, eg the J&J COVID vaccine.
Moderna vaccine has to be kept in -70 C. Viruses that can survive for any extended period of time only in -70 C won't find many hosts.
Also maybe the process of creating virus shell can't naturally be done without protein scaffold.
While this particular Moderna claim would likely affect BioNTech/Pfizer's mRNA vaccine, it's not clear whether it would survive in litigation, too.
As to a "specific string"-- if you could just pad a few codons onto the end and not be violating the patent, that's not too worthwhile.
Break it down! It's not so bad:
> A composition
A bunch of stuff
> a messenger ribonucleic acid (mRNA)
mRNA are cellular instructions on how to make proteins that are read by ribosomes that make those proteins as they read along.
> an open reading frame
This is something that starts with a "start codon" and ends with an "ending codon" and encodes valid instructions to make a protein between.
> encoding a betacoronavirus (BetaCoV) S protein or S protein subunit
The instructions refer to the spike protein of a betacoronavirus, or a fragment thereof, because this is what we want the immune system to pay attention to (and make antibodies to bind to and neutralize).
> in a lipid nanoparticle
The immune system gets pissed off about mRNA floating around, because that's one of the things that happens with active infection. So if you want this to get into cells and tell them to make your protein, you need to encase it so that it mostly escapes immune notice itself.