In the absence of approved, effective treatment for COVID-19, some hospitals treat patients with severe COVID symptoms with blood plasma from the recovery of patients. The blood of the recovered patients contains antibodies that act against the coronavirus. While plasma has not yet shown a benefit in randomized trials, some small-scale studies have suggested that it may reduce the severity of the disease and reduce hospital time.
This week at mBio, an open-access journal of the American Society for Microbiology, researchers report that antibody levels in the blood of COVID-19 patients drop rapidly within weeks after their body clears the virus and symptoms subside. If convalescent plasma is finally shown to have a clear benefit, the authors conclude, then it must be collected during a specific window of time after recovery. However, healing patients may not donate blood until at least 14 days after the symptoms have subsided, to give the body time to clean the viral particles.
“We don’t want to catch the virus, just transmit antibodies,” said Andrés Finzi, Ph.D., at the University of Montreal, Canada. “But at the same time, our work shows that plasma’s ability to neutralize viral particles decreases in those first weeks.”
The spike protein of SARS-CoV-2 plays an important role in helping the virus grab and invade host cells. Antibodies produced by the body’s immune system bind to a component of this protein and inhibit the capacity of this “key” to engage the host’s cellular “lock,” Finzi said, preventing the viral particle. infect a cell host.
Previous studies suggest that antibodies against SARS-CoV-2 spike protein peak 2 or 3 weeks after the onset of symptoms. Findings from a previous cross-sectional study of Finzi’s group, which involved more than 100 patients, suggested that the plasma’s ability to neutralize the virus was significantly reduced between 3 and 6 weeks after the onset of symptoms.
In the new longitudinal study, Finzi and his colleagues analyzed blood samples collected at one month interval from 31 individuals recovering from COVID-19. They measured the levels of immunoglobulins acting against the coronavirus S protein and tested the ability of antibodies to neutralize the virus.
The researchers observed variation in the level of individual patients but identified a consistency in the general signal: The levels of Immunoglobulins G, A, and M targeting the existing site dropped between 6 and 10 weeks after symptoms begin. At the same time, the ability of antibodies to neutralize the virus similarly fell.
Finzi’s group continues to study blood samples from patients. Understanding how antibodies levels change over time, he said, is critical not only for optimizing the use of convalescent plasma but also for understanding the effectiveness of the vaccine and whether people who were previously infected are not at risk of re-infection.
“How long do antibodies protect you?” he asked.
Finzi’s other research focuses on the immune response to the human immunodeficiency virus, or HIV, which is different from SARS-CoV-2.
References: “Rejection of Humoral Responders against SARS-CoV-2 Spike in Convalescent Individuals” by Guillaume Beaudoin-Bussières, Annemarie Laumaea, Sai Priya Anand, Jérémie Prévost, Romain Gasser, Guillaume Goyette, Halima Medjahed, Josée Perreault Tony Tremblay, Antoine Lewin, Laurie Gokool, Chantal Morrisseau, Philippe Bégin, Cécile Tremblay, Valérie Martel-Laferrière, Daniel E. Kaufmann, Jonathan Richard, Renée Bazin and Andrés Finzi, October 16, 2020, mBio.
DOI: 10.1128 / mBio.02590-20
ASM maintains the pulse of the SARS-CoV-2 pandemic along with the COVID-19 Research Registry of top-ranked research articles curated by experts. In the eyes of a pandemic, this curated database will ensure that scientists, journalists and the public have a great way to find up-to-date and most important SARS-CoV-2 / COVID-19 research from the latest journal articles and preprints.
The American Society for Microbiology is one of the largest professional societies dedicated to life sciences and is made up of 30,000 scientists and health practitioners. The mission of ASM is to promote and advance microbial sciences.
ASM will promote microbial sciences through conferences, publications, certification and educational opportunities. It enhances the capacity of the laboratory worldwide through training and resources. It provides a network for scientists in academia, industry and clinical settings. In addition, ASM promotes a deeper understanding of microbial sciences in diverse audiences.