University Of Cambridge Study Confirms That Antibodies From Prior Common Coronavirus Infections Do Not Effectively Cross-React With SARS-CoV-2 Nor Cause ADE
A new study led by researchers from University of Cambridge-UK that also involved scientists from University of Zurich-Switzerland the Fluidic Analytics Unit at Cambridge-UK has found that antibodies produced from previous common coronavirus infections do not effectively cross-react with SARS-CoV-2.
The SARS-CoV-2 Research
findings dispel all the fallacies and fake data disseminated by charlatans in that past claiming that exposure to common coronaviruses offered a degree of protection against the SARS-CoV-2 virus. The same applies with regards to claims that past flu or other kinds of common cold viral infections offers a degree of protection to the SARS-CoV-2 virus.
Certain new data findings in understanding the course and severity of SARS-CoV-2 infections have highlighted both potentially beneficial and detrimental effects of cross-reactive antibodies derived from memory immunity.
Notably, due to a significant degree of sequence similarity between SARS-CoV-2 and other members of the coronavirus family, memory B-cells that emerged from previous infections with endemic human coronaviruses (HCoVs) could be reactivated upon encountering the newly emerged SARS-CoV-2, thus prompting the production of cross-reactive antibodies.
However, determining the affinity and concentration of these potentially cross-reactive antibodies to the new SARS-CoV-2 antigens is particularly important when assessing both existing immunity against common HCoVs and adverse effects like antibody-dependent enhancement (ADE) in COVID-19.
These two fundamental parameters cannot easily be disentangled by surface-based assays like enzyme-linked immunosorbent assays (ELISAs), which are routinely used to assess cross-reactivity.
The study team used microfluidic antibody affinity profiling (MAAP) to quantitatively evaluate the humoral immune response in COVID-19 convalescent patients by determining both antibody affinity and concentration against spike antigens of SARS-CoV-2 directly in nine convalescent COVID-19 patient and three pre-pandemic sera that were seropositive for common HCoVs. All 12 sera contained low concentrations of high-affinity antibodies against spike antigens of HCoV-NL63 and HCoV-HKU1, indicative of past exposure to these pathogens, while the affinity against the SARS-CoV-2 spike protein was even lower.
The study findings showed that cross-reactivity as a consequence of memory reactivation upon an acute SARS-CoV-2 infection may not be a significant factor in generating immunity against SARS-CoV-2.
The study findings were published in the peer reviewed journal: ACS Infectious Diseases. https://pubs.acs.org/doi/10.1021/acsinfecdis.1c00486#
Though the novel SARS-CoV-2 coronavirus has taken the world by storm, it's not the only coronavirus that can infect humans.
However, unlike SARS-CoV-2, common human coronaviruses (HCoVs) generally cause only mild disease.
The study findings have shown that infections with two different HCoVs don't generate antibodies that effectively cross-react with SARS-CoV-2. So, prior infection with HCoVs is unlikely to protect against COVID-19 or worsen a SARS-Co
V-2 infection through antibody-dependent enhancement (ADE).
Although SARS-CoV-2 shares significant sequence similarity with its HCoV cousins, the study team wondered if the immune system might recognize the new coronavirus from prior bouts with HCoVs. This could re-activate memory B cells, causing them to produce antibodies that helped the person overcome previous HCoV infections, and might also help fight COVID-19.
Worryingly, if the antibodies against HCoVs recognize SARS-CoV-2, but not strongly enough to generate an immune response, they could cause ADE. In this rare condition, sub-optimal antibodies actually help some viruses attach to and enter host cells, making the infection worse.
The study team wanted to compare the strength and concentration of antibodies against HCoVs and SARS-CoV-2 in the sera of nine recovered COVID-19 patients and in three pre-pandemic sera.
The study team used a technique called microfluidic antibody-affinity profiling, which unlike the traditionally used enzyme-linked immunosorbent assay (known as ELISA), can measure both antibody affinity and concentration independently.
The study team found that all nine recovered COVID-19 sera samples contained moderate amounts of antibodies with high affinity to the SARS-CoV-2 spike protein. In contrast, none of the pre-pandemic sera contained high-affinity antibodies for SARS-CoV-2. All 12 sera contained low amounts of very high-affinity antibodies against two common HCoVs, indicating previous infections. Further studies also showed that these antibodies did not bind to SARS-CoV-2.
The study findings confirm that there is no significant cross-reactivity of antibodies against common HCoVs and SARS-CoV-2, and therefore, no expected protective or adverse effects of antibody cross-reactivity for these coronaviruses.
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