One of the big (and so far unanswered) questions about the coronavirus epidemic is what kind of immunity people have after becoming infected. This is important for the idea of “re-infection” (is it even possible?) and of course for vaccine development. We’re getting more and more information in this area, though, and this new paper is a good example. A team from the La Jolla Institute for Immunology, UNC, UCSD, and Mt. Sinai (NY) reports details about the T cells of people who have recovered from the virus.
Comparing infected patients with those who have not been exposed to the coronavirus, this team went through the list of 25 viral proteins that it produces. In the CD4+ cells, the Spike protein, the M protein, and the N protein stood out: 100% of the exposed patients had CD4+ cells that responded to all three of these. There were also significant CD4+ responses to other viral proteins: nsp3, nsp4, ORF3s, ORF7a, nsp12 and ORF8. The conclusion is that a vaccine that uses Spike protein epitopes should be sufficient for a good immune response, but that there are other possibilities as well – specifically, adding in M and N protein epitopes might do an even more thorough job of making a vaccine mimic a real coronavirus infection to train the immune system.
So overall, this paper makes the prospects for a vaccine look good: there is indeed a robust response by the adaptive immune system, to several coronavirus proteins. And vaccine developers will want to think about adding in some of the other antigens mentioned in this paper, in addition to the Spike antigens that have been the focus thus far. It seems fair to say, though, that the first wave of vaccines will likely be Spike-o-centric, and later vaccines might have these other antigens included in the mix. But it also seems that Spike-protein-targeted vaccines should be pretty effective, so that’s good. The other good news is that this team looked for the signs of an antibody-dependent-enhancement response, which would be bad news, and did not find evidence of it in the recovering patients (I didn’t go into these details, but wanted to mention that finding, which is quite reassuring). And it also looks like the prospects for (reasonably) lasting immunity after infection (or after vaccination) are good. This, from what I can see, is just the sort of response that you’d want to see for that to be the case. Clinical data will be the real decider on that, but there’s no reason so far to think that a person won’t have such immunity if they fit this profile.
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