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HOUSTON – Intranasal administration of a monoclonal IgM antibody, which neutralizes SARS-CoV-2 significantly better than previous IgG antibodies, has been shown in a preclinical study in nature (2021 DOI: 10.1038 / s41586-021-03673-2) Protecting mice from SARS-CoV-2 infection and disease, the protective effect also extends to different types of viruses.
IgM antibodies are formed earlier than IgG antibodies after virus infection. In contrast to these, they also enter the mucous membranes, where they can repel further attacks by the pathogen. IgM antibodies consist of 5 or 6 units, each with two binding sites. In principle, they can thus better intercept viruses and other pathogens than IgG antibodies, which have only two binding sites.
However, IgM antibodies are more difficult to produce than IgG antibodies, which is why they have not yet been used clinically. This may change over the next few years as some manufacturing issues have since been resolved. IGM Biosciences of Mountain View/California may, according to its own information, produce IgM preparations in sufficient quantities for use in clinical studies.
The company’s repertoire also includes IgM antibodies against SARS-CoV-2. A team led by Zhiqiang An of the UT-Health Texas Therapeutics Institute in Houston tested IgM antibodies in laboratory studies and then examined mice to see if the antibodies neutralized SARS-CoV-2 and protected the animals from infection.
The results were particularly promising with the IGM-6268 antibody, which binds more strongly to the S protein of SARS-CoV-2 (or a similar laboratory virus). In laboratory experiments, IgM antibodies also protect against various virus variants, including B.1.1.7 (England), P.1 (Brazil), and B.1.351 (South Africa) classified as of concern.
Another advantage of IgM antibodies is that they can protect mucous membranes in a targeted manner after topical application. Intranasal application will be possible without any problems in the early stage of the disease. Approved IgG antibody preparations often fail to be used because they must be administered intravenously. Even with high doses, it does not reach the mucous membranes of the airways.
US researchers reported that administration of IgM was able to protect mice from infection and significantly reduced the amount of virus in nasal and lung tissue after infection. Resorption into the systemic circulation occurs only to a very small extent, which may increase the safety of nasal application. The manufacturer wants to start clinical studies early in the fall. © rme / aerzteblatt.de