COVID-19 Antibodies: Potent Antibodies Against Other Seasonal Human Coronavirus Infections Have No Neutralizing Activity Against SARS-CoV-2
Source: COVID-19 Antibodies Aug 03, 2020 4 years, 3 months, 1 week, 4 days, 5 hours, 55 minutes ago
COVID-19 Antibodies: Researchers from Takeda Pharmaceuticals in Austria have shown that antibodies with potent neutralizing activity against a well-established seasonal coronavirus had no neutralizing activity against the SARS-CoV-2 coronavirus.
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The research findings are published on a preprint server and are pending peer review.
https://www.biorxiv.org/content/10.1101/2020.07.30.228213v1
This new research finding dispels any previous fallacies that populations that were exposed to previous seasonal human coronavirus infections might have a certain degree of immunity against the SARS-CoV-2.
The researchers carried out the study to test whether SARS-CoV-2 could potentially be neutralized by antibodies induced by seasonal coronaviruses that are already circulating.
The detailed analysis of intravenous immunoglobulin (IVIG) lots produced against human coronavirus (hCoV) 299E, a long-recognized cause of the common cold, showed high titers of neutralizing antibodies (nAbs) against the 299E virus, but no cross-neutralization effect against SARS-CoV-2.
Dr Thomas Kreil and other researchers from Baxter AG, (now owned by Takeda) Vienna, say the finding suggests that nAbs against well-known seasonal coronaviruses cannot neutralize SARS-CoV-2 and that the currently available IVIG lots would not offer any protection against the virus.
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The SARS-CoV-2 virus, the pathogenic agent that causes coronavirus disease 2019 (COVID-19), belongs to the same family of coronaviruses that includes strains currently circulating seasonally as respiratory viruses.
The volumes of plasma donations previously made by people exposed to such viruses can be pooled to produce IVIG lots containing various antibodies generated against the infectious agents.
It was believed that these IVIG lots can be used to protect immunocompromised individuals, for example, against circulating viral infections.
Upon following the emergence of a new virus, detectable levels of antibodies only occur in IVIG lots once a certain proportion of donors have contracted and recovered from the infection. Furthermore, for the lots to offer any protective, neutralizing effect, an even higher proportion of recovered donors is needed.
The SARS-CoV-2 virus belongs to the
Coronaviridae family, which includes the hCoVs 229E, NL63, OC43, and HKU1. These agents generally cause a self-limiting and mild illness, although they can also lead to more severe conditions such as pneumonia.
Considering the long-term circulation of these hCoVs, by time plasma was pooled from thousands of donors, the IVIG lots contained significant levels of nAbs.
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Whether these may cross-react or potentially even neutralize the novel and related SARS-CoV-2 remains unclear.
While some antibody binding assays have demonstrated a certain degree of cross-reactivity, but the more clinically relevant functional neutralization assays have detected no or only minimal levels of cross-neutralization.
Dr Kreil says the question is of particular clinical relevance for people with immune deficiencies (PIDs) since their health depends on whether they can be treated with immunoglobulin preparations that contain neutralizing antibodies against the various pathogens surrounding them.
He said, “SARS-CoV-2 cross-neutralizing antibodies in IVIGs, if they were present, might afford some protection to PIDs, and may even represent a treatment option for COVID-19 patients.”
In this research, the researchers finally got to test the IVIG lots produced from plasma collected in Europe and the US for nAbs against SARS-CoV-2 and the longer circulating hCoV-299E to gauge whether antibodies against existing seasonal coronaviruses might cross-neutralize SARS-CoV-2.
The study analysis showed that the IVIG lots contained high titers of nAbs against hCoV-229E. However, testing the same IVGF lots using a highly specific SARS-CoV-2 neutralization assay showed no cross-neutralization.
Dr Kreil told Thailand Medical News, “
The finding confirms that the existing hCoV-229E-specific nAbs, as well as the presumably present nAbs against the other seasonal hCoVs, have no cross-neutralizing capacity to SARS-CoV-2.”
The study team further confirmed that another study testing of 21 IVIG lots using a SARS-CoV-2 specific ELISA assay that had previously correlated with a neutralization test, also did not detect the presence of any cross-reacting antibodies.
The study team said that this, together with the current study, shows that “two experimentally robust studies have not found SARS-CoV-2 nAbs in IVIG lots produced from pre-pandemic plasma.”
The researchers concluded that therefore, “currently available IVIGs cannot be expected to afford protection from SARS-CoV-2 infection.”
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