Should further study validate these findings, clinical laboratories managing hospital blood banks would be among the first to benefit from an abundance of universal donor blood
In a surprising outcome for microbiome research, scientists at the Technical University of Denmark (DTU) and Sweden’s Lund University discovered that the bacteria Akkermansia muciniphila, which resides in the human gut, produces enzymes that can be used to process whole blood in ways that could help produce type-O blood. This “universal” blood type can be given to patients during transfusions when other blood types are in short supply.
Receiving the wrong type of blood via a transfusion could result in a fatal reaction where the immune system launches an attack on foreign antigens. As blood bankers and clinical laboratory scientists know, the A antigens in type A blood are not compatible with the B antigens in type B blood. Type-O blood completely lacks these antigens, which explains why it can be used for individuals of any blood type.
The DTU/Lund discovery—still in its initial stages of development—could eventually give blood bankers in hospital laboratories a way to expand their supply of universal type-O blood. Although individuals with type-O blood are universal donors, often the available supply is inadequate to meet the demand.
“For the first time, the new enzyme cocktails not only remove the well-described A and B antigens, but also extended variants previously not recognized as problematic for transfusion safety,” said Maher Abou Hachem, PhD, Professor of Biotechnology and Biomedicine at DTU, one of the authors of the study, in a news release.
Discovering a way that ensures any blood type can donate blood for all blood types could increase the supply of donor blood while reducing the costs and logistics affiliated with storing four separate blood types. Additionally, the production of a universal blood type using gut microorganisms could reduce the waste associated with blood products nearing their expiration dates.
“We are close to being able to produce universal blood from group B donors, while there is still work to be done to convert the more complex group A blood,” said Maher Abou Hachem, PhD (above), Professor of Biotechnology and Biomedicine at DTU in a news release. “Our focus is now to investigate in detail if there are additional obstacles and how we can improve our enzymes to reach the ultimate goal of universal blood production,” he added. Hospital clinical laboratories that manage blood banks will be among the first to benefit from this new process once it is developed and cleared for use in patient care. (Photo copyright: Technical University of Denmark.)
Creating Universal Donor Blood
The bacterium Akkermansia muciniphila is abundant in the guts of healthy humans. It produces valuable compounds, and it is able to break down mucus in the gut and can have significant, positive effects on body weight and metabolic markers.
“What is special about the mucosa is that bacteria, which are able to live on this material, often have tailor-made enzymes to break down mucosal sugar structures, which include blood group ABO antigens. This hypothesis turned out to be correct,” Hachem noted in the DTU news release.
“Instead of doing the work ourselves and synthesizing artificial enzymes, we’ve asked the question: What looks like a red [blood] cell surface? The mucus in our gut does. So, we simply borrowed the enzymes from the bacteria that normally metabolize mucus and then applied them to the red [blood] cells,” Martin Olsson MD, PhD, professor of hematology and transfusion medicine at Lund University, told Live Science. “If you think about it, it’s quite beautiful.”
The researchers successfully identified long strings of sugar structures known as antigens that render one blood type incompatible with another. These antigens define the four blood types: A, B, AB and O. They then used a solution of gut bacteria enzymes to remove the sugar molecules present on the surface of red blood cells (RBCs).
“We biochemically evaluated 23 Akkermansiaglycosyl hydrolases and identified exoglycosidase combinations which efficiently transformed both A and B antigens and four of their carbohydrate extensions,” the study authors wrote in Nature Microbiology. “Enzymatic removal of canonical and extended ABO antigens on RBCs significantly improved compatibility with group O plasmas, compared to conversion of A or B antigens alone. Finally, structural analysis of two B-converting enzymes identified a previously unknown putative carbohydrate-binding module.”
“Universal blood will create a more efficient utilization of donor blood, and also avoid giving ABO-mismatched transfusions by mistake, which can otherwise lead to potentially fatal consequences in the recipient. When we can create ABO-universal donor blood, we will simplify the logistics of transporting and administering safe blood products, while at the same time minimizing blood waste,” Olsson said in the news release.
Future Progress
The researchers have applied for a patent for the enzymes and their method of enzyme treatment. The two educational institutions hope to make further progress on this joint project over the next three years. They eventually hope to test their theory in controlled patient trials and make it available for commercial production and clinical use.
More research and clinical studies are needed to prove the effectiveness of this discovery. Clinical laboratory professionals—particularly those who manage hospital blood banks—will want to follow DTU’s research. It could someday lead to the availability of a more abundant supply of universal donor blood for transfusions.
Researchers find declining antibody levels in SARS-CoV-2 patients are offset by T cells and B cells that remain behind to fight off reinfection
Questions remain regarding how long antibodies produced by a COVID-19 vaccine or natural infection will provide ongoing protection against SARS-CoV-2. However, a new study showing COVID-19 immunity may be “robust” and “long lasting” may signal important news for clinical laboratories and in vitro diagnostics companies developing serological tests for the coronavirus disease.
The LJI research team analyzed blood samples from 188 COVID-19 patients, 7% of whom had been hospitalized. They measured not only virus-specific antibodies in the blood stream, but also memory B cell infections, T helper cells, and cytotoxic (killer) T cells.
While antibodies eventually disappear from the blood stream, T cells and B cells appear to remain to fight future reinfection.
“As far as we know, this is the largest study ever for any acute infection that has measured all four of those components of immune memory,” Crotty said in a La Jolla Institute news release.
The LJI researchers found that virus-specific antibodies remained in the blood stream months after infection while spike-specific memory B cells—which could trigger an accelerated and robust antibody-mediated immune response in the event of reinfection—actually increased in the body after six months. In addition, COVID-19 survivors had an army of T cells ready to halt reinfection.
“Our data show immune memory in at least three immunological compartments was measurable in ~95% of subjects five to eight months post symptom onset, indicating that durable immunity against secondary COVID-19 disease is a possibility in most individuals,” the study concludes. The small percentage of the population found not to have long-lasting immunity following COVID-19 infection could be vaccinated in an effort to stop reinfection from occurring on the way to achieving herd immunity, the LJI researchers maintained.
Do COVID-19 Vaccines Create Equal Immunity Against Reinfection?
Whether COVID-19 vaccinations will provide the same immune response as an active infection has yet to be determined, but indications are protection may be equally strong.
“It is possible that immune memory will be similarly long lasting similar following vaccination, but we will have to wait until the data come in to be able to tell for sure,”
LJI Research Professor Daniela Weiskopf, PhD, said in the LJI statement. “Several months ago, our studies showed that natural infection induced a strong response, and this study now shows that the response lasts. The vaccine studies are at the initial stages, and so far, have been associated with strong protection. We are hopeful that a similar pattern of responses lasting over time will also emerge for the vaccine-induced responses.”
The study’s authors cautioned that people previously diagnosed with COVID-19 should not assume they have protective immunity from reinfection, the Washington Post noted. In fact, according to the LJI news release, researchers saw a “100-fold range in the magnitude of immune memory.”
Alessandro Sette, Doctor of Biological Sciences (above), an Italian immunologist, Professor at the Center for Autoimmunity and Inflammation/Center for Infectious Disease and Vaccine Research at La Jolla Institute for Immunology, and co-author of the study, told the Washington Post that people should act responsibly. “If I had COVID, I would still not throw away my masks, I would not go to rave parties … It’s like driving a car where you know you have 90% probability that the brakes work.” (Photo copyright: La Jolla Institute for Immunology.)
Previous Studies Found Little Natural Immunity Against SARS-CoV-2 Reinfection
The Scientist reported that several widely publicized previous studies raised concerns that immunity from natural infection was fleeting, perhaps dwindling in weeks or months. And a United Kingdom study published in Nature Microbiology found that COVID-19 generated “only a transient neutralizing antibody response that rapidly wanes” in patients who exhibited milder infection.
Daniel M. Davis, PhD, Professor of Immunology at the University of Manchester, says more research is needed before scientists can know for certain how long COVID-19 immunity lasts after natural infection.
“Overall, these results are interesting and provocative, but more research is needed, following large numbers of people over time. Only then, will we clearly know how many people produce antibodies when infected with coronavirus, and for how long,” Davis told Newsweek.
While additional peer-reviewed studies on the body’s immune response to COVID-19 will be needed, this latest study from the La Jolla Institute for Immunity may help guide clinical laboratories and in vitro diagnostic companies that are developing serological antibody tests for COVID-19 and lead to more definitive answers as to how long antibodies confer protective immunity.
