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The severe acute respiratory syndrome virus coronavirus 2 (SARS-CoV-2) emerged from Wuhan, China in late 2019 and rapidly spread around the world, progressing into a full-fledged pandemic. As this is a new virus, scientists around the world immediately began work on developing a vaccine or effective therapeutic agents to fight SARS-CoV-2.
The use of convalescent plasma in the treatment of infectious diseases
Convalescent plasma has now been identified as a potential treatment option for coronavirus disease (COVID-19). Convalescent plasma has been used in the past to treat infectious diseases, such as during the Spanish flu pandemic and the more recent SARS and Middle East respiratory syndrome (MERS) outbreaks.
Although convalescent plasma has some disadvantages, such as variations in nature and the neutralizing power of antibodies in plasma from one donor to another, many can be overcome by purifying and concentrating antibodies in pharmaceutical preparations. Human immunoglobulin products derived from plasma pools of convalescent or vaccinated donors have been used for several years in the treatment of various infectious diseases.
Convalescent purifying plasma to produce anti-SARS-CoV-2 hyperimmune globulin
In a recent study published in the prepress server bioRxiv*, researchers from the Grifols Bioscience Research Group reported on convalescent plasma collection and production of anti-SARS-CoV-2 hyperimmune globulin for use in clinical research.
Researchers collected convalescent plasma from donors who are part of an existing network of plasma donation centers. Hyperimmune globulin was produced using a caprylate / chromatography purification process. Initial batches of the anti-SARS-CoV-2 or hIVIG hyperimmune globulin were produced in a small-scale facility built specifically to address emerging infectious diseases.
Treatment of the convalescent plasma produced a highly purified IgG product with concentrated neutralizing antibody activity. Therefore, this hyperimmune globulin allows for the delivery of higher antibody activity per volume unit with less potential for adverse reactions associated with plasma administration.
The final product had over 10 times the SARS-CoV-2 specific IgG antibody
In the process of purification of the convalescent plasma in the final product, the concentration of IgG and the IgG antibody specific to SARS-CoV-2 increased more than 10 times. The neutralizing activity of antibodies increased nearly 3-fold from the plasma pool to the final hyperimmune globulin. This 3-fold increase in neutralizing activity is less than expected based on the ELISA titer, which the authors believe may be due to the lack of IgA and IgM contributions removed during IgG purification. Normalized ELISA activity was maintained throughout the process.
“The antibody neutralization activity increased approximately threefold from the plasma pool to the final product.”
In the final product batches, the protein content was 100% IgG with 98% monomer and dimer forms. Levels of potentially dangerous proteins such as IgM, IgA and anti-A, anti-B and anti-D antibodies have been minimized as much as possible. Therefore, the authors report that they have successfully produced multiple batches of anti-SARS-CoV-2 hyperimmune globulin from convalescent human plasma and HIVIG has produced regulatory requirements met.
Anti-SARS-CoV-2 hyperimmune globulin has more diverse antibodies with wider antiviral activity
A potential advantage of this anti-SARS-CoV-2 hyperimmune globulin over direct administration of plasma from donors is the diversity of antibodies acquired from a convalescent pool of donors. These different antibodies can offer a much wider range of antiviral activity by targeting multiple viral epitopes and recruiting different cellular mechanisms. The authors believe this diversity may also be important in terms of overcoming viral mutations.
“A potential advantage of hIVIG over direct administration of plasma from individuals or a monoclonal antibody is the diversity of antibodies obtained from a convalescent donor pool that can deliver a wider range of antiviral activity.”
Overall, the processes described in this study resulted in the production of multiple batches of anti-SARS-CoV-2 hyperimmune globulin that met all regulatory requirements. Furthermore, previous experience with hyperimmune globulin products used in the treatment of tetanus, rabies and hepatitis B offers a reasonable expectation for the safety and efficacy of anti-SARS-CoV-2 hyperimmune globulin.
Clinical trials have been started to analyze the effectiveness of this hyperimmune globulin. The Coronavirus Immunoglobulin Inpatient Treatment Study (ITAC) is the first clinical study in which hyperimmune globulin is evaluated.
*Important Notice
bioRxiv publishes preliminary scientific reports that are not peer-reviewed and therefore should not be considered conclusive, guide clinical practice / health-related behaviors, or treated as consolidated information.
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