Thread by @sailorrooscout

Researchers in South Africa have found that antibodies of those previously infected with 501Y.V2 (B.1.351) are cross-reactive and thereby able to neutralize other variants of SARS-CoV-2 and prevent infection from other variants. Let’s discuss! 🧵
biorxiv.org/content/10.110…

Their research demonstrates immune response to B.1.351 is as potent as that seen in those infected with the original variant. Furthermore, antibodies from people infected with B.1.351 are not only able to neutralize B.1.351 but variant P.1 as well.

Blood samples from 89 patients in Cape Town, South Africa previously infected with SARS-CoV-2 were collected and sequenced. Their samples were all found to be that of B.1.351 by phylogenetic analysis. From previous accounts, we are aware that B.1.351 attributed to over 90% of

the infections in South Africa between December 2020 and January of this year. No patient reported prior SARS-CoV-2 infection. Researchers assessed the magnitude of the binding and neutralizing antibody responses in the GSH patients to the B.1.351 spike protein and found

observed no significant difference in the magnitude of binding or neutralizing responses between the GSH cohort and the wave 1 admission samples, but titers at the follow-up timepoint were significantly higher in the wave 1 cohort than in the GSH cohort. Similar to the original

variant, B.1.351 elicits high titer binding and neutralizing antibody responses. Researchers then assessed the magnitude of binding responses to the SBD and spike domain of the original variant and B.1.351 and observed that infection with B.1.351 elicits cross-reactive binding

antibodies to the RBD and the full spike protein. Researchers also found that although plasma samples had higher titers to the spike of B.1.351 than to that of the original variant (average reduction of 1.7-fold), high level binding to the original variant remained. This

demonstrates plasma binding antibodies elicited by individuals infected with B.1.351 are able to cross-react with that of the original circulating variant. Lastly, researchers previously reported substantially lower neutralization of B.1.351 by plasma from individuals infected

with the original variant, with 48% of sera unable to neutralize B.1.351. Here they performed the reverse experiment, by assessing the cross- reactivity of neutralizing responses in the GSH 501Y.V2 (B.1.351) cohort, against the original variant and 501Y.V3 (P.1).

Researchers found that the neutralizing antibodies elicited by B.1.351 infection are more cross-reactive than those from patients infected with the original variant and can neutralize not only the original variant but P.1 as well. So what does this mean? A couple things. Firstly,

this data suggests that much of the neutralization activity against B.1.351 is directed against the RBD. Secondly, since the majority of infections are mild/moderate, understanding both the cross-reactivity and durability of lower titer responses in B.1.351 infection

will be important for predicting re-infection risk. Furthermore, studies of the cross-reactivity of the immune responses raised to other variants need to be performed. Plasma from individuals infected with variant B.1.1.7 first detected in the UK, show reduced

titers against B.1.351 suggesting this spike does not elicit particularly cross-reactive antibodies. This is similar to observations using samples from individuals infected with the original variant that lost neutralizing activity against B.1.351. Overall, this study gives us

insight and data suggests the antibody response in patients infected with B.1.351 have broad specificity. Therefore, the vaccines currently being designed/tested that built upon the spike protein of variant B.1.351 may elicit more cross-reactive neutralizing antibody responses.

For those asking, yes, this is good news. It gives us another piece to this puzzle that we desperately need in understanding this virus and how to further increase the effectiveness of our vaccines for the future. Not to mention, pair this with our TCRs and it looks bright.