Tag: antibodies

Categories : PaediatricsTags :

Antibodies in Breastmilk Protect Infants Against Rotavirus

On By ModernMedia
Photo by Wendy Wei: https://www.pexels.com/photo/mother-breastfeeding-her-child-3074935/

A study led by researchers at the found that breast milk provides protection against rotavirus, a common gastrointestinal disease in infants. Babies whose mothers had high levels of specific antibodies in their breast milk were able to fend off the infection for a longer period than infants whose mothers had lower levels. The researchers also uncovered an unexpected relationship between BMI and antibody levels.

Published in the Journal of Clinical Investigation, the University of Rochester Medical Center-led study also found significant differences in antibody profiles in breast milk between mothers in high-income countries (HICs) and low- and middle-income countries (LMICs). Researchers analysed human milk samples from 695 women in Finland, the US, Pakistan, Peru, and Bangladesh, and measured specific IgA and IgG antibodies, which are common antibodies produced in breast milk, against 1607 proteins from 30 pathogens.

The research, led by Dr Kirsi Jarvinen-Seppo, MD, PhD, professor at UR Medicine Golisano Children’s Hospital (GCH), tracked antibody levels and kinetics over time to analyse antibody responses to a wide range of respiratory, diarrhoeal and sepsis pathogens in human milk. The primary aim of the study, funded by the Bill and Melinda Gates Foundation, was to understand the protective properties of these antibodies and how they vary across different geographic and economic regions.

“We would expect to find differences in antibody levels in different countries, due to different diseases circulating among areas of the world, but this is one of the first times that there’s been a head-to-head comparison for dozens of pathogens across several continents,” said Jarvinen-Seppo. “It was encouraging to see such a clear link between higher antibody levels and a delay to rotavirus infection, and this was consistently observed among an independent validation cohort.”  

Other notable findings from the study:

  • Milk from women in LMICs had higher levels of IgA and IgG antibodies against various intestinal and respiratory pathogens compared to milk from HICs. This difference was particularly notable for pathogens such as Shigella and pneumococcus, which are major contributors to morbidity and mortality in young children.
  • Higher body mass index (BMI) was associated with lower antibody levels, which went against expectations.

“The variation in antibody profiles between regions highlights the impact of economic and environmental factors on maternal immunity,” said Jarvinen-Seppo.

In addition to Rotavirus findings, the discovery that a higher BMI was associated with lower antibody counts in breast milk was also unexpected.

“We had anticipated that underweight mothers might have lower antibody levels due to poorer nutritional status,” said Jarvinen-Seppo. “Due to rising obesity rates worldwide, this could be a significant finding, but this is preliminary and additional research is needed since this is the first time this has been measured.”

“While the data on rotavirus protection is compelling, the geographical and BMI-related variations highlight areas where further research is essential. The study sets the stage for additional investigations that could lead to better understanding and interventions for improving infant health globally,” said Jarvinen-Seppo.

Source: University of Rochester Medical Center

Categories : COVID VaccinesTags :

COVID Vaccination and Antibody Responses Found to be Long-lasting

On By ModernMedia
Image by Fusion Medical on Unsplash

A long-term analysis conducted by leading microbiologists at the Icahn School of Medicine at Mount Sinai reveals that antibody responses induced by COVID vaccines are long-lasting. The study results, published online in the journal Immunity, challenge the idea that mRNA-based vaccine immunity wanes quickly.

The emergence of SARS-CoV-2 in late 2019 sparked the global pandemic that is now in its fifth year. Vaccines that were developed at record speed have saved millions of lives. However, the emergence of SARS-CoV-2 variants and waning immunity have decreased the effectiveness of the vaccines against symptomatic disease. The common perception now is that mRNA-based vaccine-induced immunity wanes quickly. However, this assumption is largely based on data from short-term studies that include a very limited number of data points following peak responses.

The Mount Sinai research team’s analysis of more than 8000 samples collected over a three-year period in New York City examined how antibody responses to the virus’s spike protein changed after infections, during the primary immunisation series, during monovalent and bivalent booster vaccination, and during breakthrough infections.

They found that upon primary immunisation, participants with pre-existing immunity (those who had previously been infected with the virus) mounted higher antibody responses faster and achieved higher steady-state antibody titres than individuals who had not been previously infected. The waning of antibody response was characterised by two phases: an initial rapid decay from the strong peak after vaccination, followed by a stabilisation phase with very slow decay, suggesting that antibody levels were very long-lasting. Booster vaccination equalised the differences in antibody concentration between participants with and without pre-existing immunity. Breakthrough infections increased antibodies to similar levels as an additional vaccine dose in individuals who had not previously been infected.

This investigation represents one of the most extensive and in-depth assessments of the longevity of SARS-CoV-2 immune responses to date. Its major conclusion is that changes in the virus that allow it to evade immunity, rather than waning immunity, are the major reason for breakthrough infections.

“Ours is one of the longest-running COVID-19 studies out there,” said Viviana Simon, MD, PhD, Professor of Microbiology, Medicine and Pathology, Molecular and Cell-Based Medicine, at Icahn Mount Sinai and lead author of the paper. “Following the same group of people monthly over time is rare and powerful because you can compare immune responses on an individual level. SARS-CoV-2 continues to evolve, so this research is important to provide an understanding about the impact of new variants and new vaccine doses on a healthy immune system, and to guide all of us to make the best choices to maintain protection against the virus that continues to circulate in our communities.”

This in-depth analysis was made possible through the Protection Associated with Rapid Immunity to SARS-CoV-2 (PARIS) study, an observational, longitudinal cohort of health care workers of the Mount Sinai Health System that was initiated in April 2020. At that time, the densely populated New York metropolitan area was hit with an exponential increase in severe SARS-CoV-2 infections, and essential workers in the health care system were at high risk for infection. In response to the crisis, a team of leading virologists, physician-scientists, and pathologists at Mount Sinai established a specific and sensitive SARS-CoV-2 binding enzyme-linked immunosorbent assay to accurately measure the SARS-CoV-2 antibody titres. This test was used to measure immune responses in the PARIS cohort in order to determine how quickly the antibody defences were mounted and much these changed over the months and years of follow up.

In addition to showing the impact on a person’s individual antibody response to vaccines based on the type of vaccine received and whether or not they were infected before receiving the first dose, the PARIS study made possible the development of a mathematical model that can be used to predict and characterize antibody responses of both individual people and populations.

“People have pandemic fatigue and vaccine uptake has slowed, especially after the vaccines started to be charged to insurance,” said Komal Srivastava, MS, Director of Strategy and Operation of the Mount Sinai Center for Vaccine Research and Pandemic Preparedness and co-first author of the paper. “We were pleasantly surprised to see that the booster doses promoted a large antibody response regardless of a person’s personal infection history, so we are hopeful that our study findings will encourage people to get their vaccine boosters when eligible and to stay engaged in research. Our work also showcases the impact of viral evolution over time and why it’s critical to keep studies like this going, despite the pandemic fatigue.”

According to the research team, the PARIS model has broad applications for studying the kinetics of antibodies produced to different COVID vaccines in diverse populations. They stress much more work remains to analyse side effects, applications of the antibody model and continued research about new vaccines and viral variants.

“This study adds an essential piece of data to understand the intricate immune response elicited by SARS-CoV-2 infection and COVID-19 vaccination,” says Juan Manuel Carreno Quiroz, PhD, Assistant Professor in the Department of Microbiology and co-first author of the paper. “In light of the emerging viral variants, which predominantly induce a cross-reactive antibody response against the spike protein, it will be exciting to characterise in depth the role of these antibodies – in particular the non-neutralising ones – in protection against the most recent circulating viral variants. Likewise, monitoring the induction of variant-specific antibodies after multiple exposures by breakthrough infections and by administration of updated COVID-19 vaccines, such as the XBB.1.5 monovalent booster, will be key to understand the evolution of the antibody response over time.”

Source: The Mount Sinai Hospital / Mount Sinai School of Medicine

Categories : Neurodegenerative DiseasesTags :

Epstein–Barr Virus Antibodies may Trigger Multiple Sclerosis

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Source: CC0

Researchers at Karolinska Institutet have found further links between Epstein–Barr virus and multiple sclerosis. A study published in Science Advances shows that some individuals have antibodies against the virus that mistakenly attack a protein in the brain and spinal cord.

Many years ago, the Epstein–Barr virus (EBV), which infects most people early in life and then usually lies dormant was linked to multiple sclerosis (MS) but the reason remained a mystery. Increasing evidence, including two papers published in Science and Nature last year, suggests that EBV infection precedes MS and that antibodies against the virus may be involved. However, the molecular mechanisms seem to vary between patients and remain largely unknown.

“MS is an incredibly complex disease, but our study provides an important piece in the puzzle and could explain why some people develop the disease,” says Olivia Thomas, postdoctoral researcher at the Department of Clinical Neuroscience, Karolinska Institutet and shared first author of the paper. “We have discovered that certain antibodies against the Epstein-Barr virus, which would normally fight the infection, can mistakenly target the brain and spinal cord and cause damage.”

The researchers analysed blood samples from more than 700 patients with MS and 700 healthy controls. They found that antibodies that bind to a certain protein in the Epstein-Barr virus, EBNA1, can also bind to a similar protein in the brain and spinal cord called CRYAB, whose role is to prevent protein aggregation during conditions of cellular stress such as inflammation. These misdirected, cross-reactive antibodies may damage the nervous system and cause severe symptoms in MS patients, including problems with balance, mobility and fatigue. The antibodies were present in about 23 percent of MS patients and 7% of control individuals.

“This shows that, whilst these antibody responses are not required for disease development, they may be involved in disease in up to a quarter of MS patients,” says Olivia Thomas. “This also demonstrates the high variation between patients, highlighting the need for personalised therapies. Current therapies are effective at reducing relapses in MS but unfortunately, none can prevent disease progression.”

“We are now expanding our research to investigate how T cells fight EBV infection and how these immune cells may damage the nervous system in multiple sclerosis and contribute to disease progression,” says joint first author of the paper Mattias Bronge, affiliated researcher at the Department of Clinical Neuroscience, Karolinska Institutet.

Source: Karolinska Institutet

Categories : COVID VaccinesTags :

COVID Vaccination Protection Wanes Faster in People with Obesity

On By ModernMedia
Antibodies by Pikisuperstar on Freepix

According to new research from the Universities of Cambridge and Edinburgh, COVID vaccination protection in people with severe obesity wanes faster than in people of normal weight. The study suggests that people with obesity are likely to need more frequent booster doses to maintain their immunity.

Previous studies on COVID vaccines have suggested that antibody levels may be lower in vaccinated people who have obesity and that they may remain at higher risk of severe disease than vaccinated people with normal weight. The reasons for this have, however, remained unclear.

This study, published in the journal Nature Medicine, shows that the ability of antibodies to neutralise the virus (their ‘neutralisation capacity’) declines faster in vaccinated people who have obesity. The findings have important implications for vaccine prioritisation policies around the world.

During the pandemic, people with obesity were more likely to be hospitalised, require ventilators and to die from COVID. In this study, supported by the NIHR Bioresource and funded by UKRI, the researchers set out to investigate how far two of the most extensively used vaccines protect people with obesity compared to those with a normal weight, over time.

A team from the University of Edinburgh looked at real-time data tracking the health of 3.5 million people in the Scottish population as part of the EAVE II study. They looked at hospitalisation and mortality from COVID in adults who received two doses of COVID vaccine (either Pfizer-BioNTech or AstraZeneca).

They found that people with severe obesity (a BMI > 40kg/m2) had a 76% higher risk of severe COVID outcomes, compared to those with a normal BMI. A modest increase in risk was also seen in people with obesity (30-39.9kg/m2), which affects a quarter of the UK population, and those who were underweight. ‘Break-through infections’ after the second vaccine dose also led to hospitalisation and death sooner (from 10 weeks) among people with severe obesity, and among people with obesity (after 15 weeks), than among individuals with normal weight (after 20 weeks).

University of Edinburg leader Prof Sir Aziz Sheikh said: “Our findings demonstrate that protection gained through COVID vaccination drops off faster for people with severe obesity than those with a normal body mass index. Using large-scale data assets such as the EAVE II Platform in Scotland have enabled us to generate important and timely insights that enable improvements to the delivery of COVID vaccine schedules in a post-pandemic UK.”

The University of Cambridge team studied people with severe obesity attending the Obesity clinic at Addenbrooke’s Hospital in Cambridge, and compared the number and function of immune cells in their blood to those of people of normal weight.

They studied people six months after their second vaccine dose and then looked at the response to a third ‘booster’ vaccine dose over time. The Cambridge researchers found that six months after a second vaccine dose, people with severe obesity had similar levels of antibodies to the COVID virus as those with a normal weight – but those antibodies were less effecctive.

The antibodies’ neutralisation capacity was reduced in 55% of individuals with severe obesity were found to have unquantifiable or undetectable ‘neutralising capacity’ compared to 12% of people with normal BMI.

“This study further emphasises that obesity alters the vaccine response and also impacts on the risk of infection,” said first author Dr Agatha van der Klaauw. “We urgently need to understand how to restore immune function and minimise these health risks.”

The researchers found that antibodies produced by people with severe obesity were less effective at neutralising the SARS-CoV-2 virus, potentially because the antibodies were not able to bind to the virus with the same strength.

When given a third (booster) dose of a COVID vaccine, neutralisation capacity was restored in both the normal weight and severely obese groups. But the researchers found that immunity again declined more rapidly in people with severe obesity, putting them at greater risk of infection with time.

Categories : Immune SystemTags :

Antibodies can Prevent Bacteria from Infiltrating Cells

On By ModernMedia
Adhesion of Bartonella henselae to human cells. B. henselae  (strain Marseille) bacteria (light blue) in an early stage infection process (30 min) to human HeLa-229 cells (red). Adhesion to host cells is mediated by specific interactions between B. henselae  surface proteins and components of the host extracellular matrix including molecules such as fibronectin or collagen. Scale bar: 8 μm.

Using Bartonella henselae bacteria, the cause of cat scratch disease, researchers have demonstrated for the first time that antibodies can prevent certain surface proteins of bacterial pathogens from entering host cells. The findings are important for the development of new drugs against highly resistant infectious agents.

Infections pose a significant threat to human health, especially when pathogens manage to colonise the organism and subsequently cause severe infections. The first step in such an infection always consists of the pathogens attaching themselves to the host cells’ surface. From here, the infections spread, resulting, for example, in infections of deeper tissue layers and organs.

A group of scientists surrounding Prof. Volkhard Kempf from Frankfurt University Hospital’s Institute of Microbiology and Hospital Hygiene has now succeeded in blocking this adhesion mechanism in a bacterium, thereby preventing the infection of host cells. For this purpose, the researchers examined the pathogen Bartonella henselae, usually causing cat scratch disease. Transmitted by cats, the disease mainly affects young children, whose symptoms include swollen and hardened lymph nodes around the site of infection, usually after a scratch or bite injury caused by infected cats.

Bartonella bacteria infect so-called endothelial cells, which line the blood vessels. Via their surface protein Bartonella adhesin A (BadA), they attach themselves to a protein (fibronectin) of the so-called “extracellular matrix,” a network of protein fibers that lie on top of the endothelial cells.

Breaking BadA

To determine which parts of the BadA protein are important in the bacterial adhesion process, the researchers equipped Bartonella bacteria with various genetically modified BadA variants, among others, and then analysed the extent to which these variants were still able to bind fibronectin. Once it was clear which BadA segments were responsible for the binding, the team produced antibodies against them, demonstrating for the first time that such antibodies can prevent infection by such bacteria.

Prof. Volkhard Kempf explains: “Bartonella henselae is not a very dangerous pathogen, and in most cases, cat scratch disease does not require any specific medical treatment. However, for us Bartonella henselae is a very important model organism for far more dangerous pathogens such as Acinetobacter baumannii, a serious pathogen that usually causes wound infection or pneumonia and often shows resistance to several last-choice antibiotics. The BadA protein of Bartonella henselae belongs to the so-called ‘trimeric autotransporter adhesins’, which are also responsible for adhesion to human cells in Acinetobacter and a number of other pathogens. A drug-induced blocking of these adhesins is therefore a promising novel and future approach to combat dangerous bacterial infections.”

The researchers published their findings in Diagnostics.

Source: Goethe University Frankfurt

Categories : COVIDTags :

New Omicron Variant Escapes Antibodies and Monoclonal Therapy

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Source: Fusion Medical Animation on Unsplash

The emerging Omicron variant BA.2.75.2 largely evades neutralising antibodies in the blood and resists several monoclonal antibody antiviral treatments, according to a study published in the journal The Lancet Infectious Diseases. The findings suggest a risk of increased COVID infections in the northern hemisphere’s winter, unless the new updated bivalent vaccines help to boost immunity in the population.

“While antibody immunity is not completely gone, BA.2.75.2 exhibited far more dramatic resistance than variants we’ve previously studied, largely driven by two mutations in the receptor binding domain of the spike protein,” said the study’s corresponding author Ben Murrell, assistant professor at the Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet.

The study shows that antibodies in random serum samples from 75 blood donors in Stockholm were approximately only one-sixth as effective at neutralising BA.2.75.2 compared with the now-dominant variant BA.5. The serum samples were collected at three time points: in November 2021 before the emergence of Omicron, in April 2022 after a large wave of infections in the country, and at the end of August to early September after the BA.5 variant became dominant.

The researchers found that only one of the clinically available monoclonal antibody treatments that were tested, bebtelovimab, managed to effectively neutralise the new variant.

BA.2.75.2 is a mutated version of another Omicron variant, BA.2.75. Since it was first discovered earlier this fall, it has spread to several countries but so far represents only a minority of registered cases.

A possible increase in infections

“We now know that this is just one of a constellation of emerging variants with similar mutations that will likely come to dominate in the near future,” Ben Murrell says, adding “we should expect infections to increase this winter.”

Some questions remain. It is unclear whether these new variants will drive an increase in hospitalisation rates. Also, while current vaccines have, in general, had a protective effect against severe disease for Omicron infections, there is not yet data showing the degree to which the updated COVID vaccines provide protection from these new variants. “We expect them to be beneficial, but we don’t yet know by how much,” Ben Murrell says.

Source: Karolinska Institutet

Categories : Diseases, Syndromes and Conditions New Compounds and TreatmentsTags :

Two New Antibody Treatments for Crohn’s Disease Equally Effective

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Anatomy of the gut
Source: Pixabay CC0

In a clinical trial, two new antibody treatments for Crohn’s disease were approximately similar in effectiveness, according to findings published in The Lancet.

This allows clinicians and patients to make treatment choices based on tolerance, according to Stephen Hanauer, MD, the Clifford Joseph Barborka Professor and a co-author of the study.

“The safety and efficacy of two agents with different mechanisms of action appears to be quite comparable over one year,” said Prof Hanauer.

Crohn’s disease (CD) is a chronic, progressive inflammatory bowel disease, causing abdominal pain, weight loss and fatigue. Treatment has usually focused on alleviating symptoms to achieve clinical remission using corticosteroids or immunomodulators, but more effective treatment is still needed, according to Prof Hanauer.

‘While there are numerous therapies and mechanisms of action for drugs approved for moderate-severe Crohn’s disease there has been a therapeutic ceiling as far as outcomes are concerned, with usually less than 50% of patients in long-term remission,” Prof Hanauer explained.

Recently, several biologic agents have been approved for use. Adalimumab is a monoclonal antibody that reduces inflammatory cytokines by inhibiting tumor necrosis factor alpha. Ustekinumab is another monoclonal antibody, though the drug targets a different set of proteins: interleukin (IL) 12 and IL-23.

Researchers recruited with Crohn’s disease, randomising 191 to receive ustekinumab and 195 to adalimumab. Patients reaching clinical remission were similar between both groups: 65% of 191 patients in the ustekinumab group versus 61% of 195 in the adalimumab group. There were no deaths through one year of study, though slightly more patients in the ustekinumab group discontinued study treatment. Disease severity measures decreased similarly over the study.

Both treatment regimens resulted in clinical remission with similar toxicity profiles.

“There are numerous options for patients with moderate-severe disease. However, the key is to treat patients with an effective regimen and treat to targets as early in the course as possible since we do not have any drugs that impact on fibrosis once it occurs,” Prof Hanauer said.

Source: Northwestern University

Categories : UncategorizedTags :

Secrets of Pregnant Mothers’ ‘Super Antibodies’ Revealed

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Pregnant with ultrasound image
Source: Pixabay

Pregnant mothers have the ability to confer greater immunity to the vulnerable developing foetus with ‘super antibodies’. Now, a far-reaching study published in Nature provides a surprising explanation of how this actually works, and what it could mean for preventing death and disability from a wide range of infectious diseases.

The findings suggest the amped-up antibodies that expecting mothers produce could be mimicked to create new drugs to treat diseases as well as improved vaccines to prevent them.

“For many years, scientists believed that antibodies cannot get inside cells. They don’t have the necessary machinery. And so, infections caused by pathogens that live exclusively inside cells were thought to be invisible to antibody-based therapies,” said Sing Sing Way, MD. “Our findings show that pregnancy changes the structure of certain sugars attached to the antibodies, which allows them to protect babies from infection by a much wider range of pathogens.”

“The maternal-infant dyad is so special. It’s the intimate connection between a mother and her baby,” says John Erickson, MD, PhD, first-author of the study.

Drs Way and Erickson are both part of Cincinnati Children’s Center for Inflammation and Tolerance and the Perinatal Institute, which strives to improve outcomes for all pregnant women and their newborns.

Erickson continues, “This special connection starts when babies are in the womb and continues after birth. I love seeing the closeness between mothers and their babies in our newborn care units. This discovery paves the way for pioneering new therapies that can specifically target infections in pregnant mothers and newborns babies. I believe these findings also will have far-reaching implications for antibody-based therapies in other fields.”

How mothers make super antibodies
The new study identifies the specific change in the sugar. During pregnancy, the “acetylated” form of sialic acid (one of the sugars attached to antibodies) shifts to the “deacetylated” form. This subtle molecular shift lets immunoglobulin G (IgG) take on an expanded protective role by stimulating immunity through receptors that respond specifically to deacetylated sugars.

“This change is the light switch that allows maternal antibodies to protect babies against infection inside cells,” Dr Way said.

“Mothers always seem to know best,” Dr Erickson added.

Revved-up antibodies can be produced in the lab
The research team pinned down the key biochemical differences between antibodies in virgin mice compared to pregnant ones. They also identified the enzyme naturally expressed during pregnancy responsible for driving this transformation.

Further, the team successfully restored lost immune protection by supplying lab-grown supplies of the antibodies from healthy pregnant mice to pups born to mothers that were gene-edited to lack the ability to remove acetylation from antibodies to enhance protection.

Hundreds of monoclonal antibodies have been produced as potential treatments for various disorders, including COVID, with a variety of results.

Dr Way said this molecular alteration can be replicated to change how antibodies stimulate the immune system to fine-tune their effects. This potentially could lead to improved treatments for infections caused by other intracellular pathogens including HIV and respiratory syncytial virus (RSV), a common virus that poses serious risks to infants.

Another reason to accelerate vaccine development
“We’ve known for years the many far-reaching benefits of breastfeeding,” Dr Erickson said. “One major factor is the transfer of antibodies in breastmilk.”

The study shows that nursing mothers retain the molecular switch, passing through the antibodies to their newborns.

Additionally, Dr Way says the findings underscore the importance of receiving all available vaccines for women of reproductive age – as well as the need for researchers to develop even more vaccines against infections that which are especially prominent in women during pregnancy or in newborn babies.

“The immunity needs to exist within the mother for it to be transferred to her child,” Dr Way said. “Without natural exposures or immunity primed by vaccination, when that light switch flips during pregnancy, there’s no electricity behind it.”

Source: Cincinnati Children’s Hospital Medical Center

Categories : COVID VaccinesTags :

New Vaccines Could Focus on T Cell Response – Without Antibodies

On By ModernMedia
T cell
Scanning Electron Micrograph image of a human T cell. Credit: NIH/NIAID

In a groundbreaking new study, scientists report training T cells to protect against SARS-CoV-2 even without an antibody response. This could open the way to more broadly effective vaccines.

The study’s findings appear in the Proceedings of the National Academy of Sciences.

Current vaccines prompt the creation of antibodies and immune cells that recognise the spike protein. However, these vaccines were developed using the spike protein from an older variant of SARS-CoV-2, reducing their effectiveness against newer variants. Researchers have found that immune cells called T cells tend to recognise parts of SARS-CoV-2 that don’t mutate rapidly. T cells coordinate the immune system’s response and kill cells that have been infected by the SARS-CoV-2 virus.

A vaccine that prompted the body to create more T cells against SARS-CoV-2 could help prevent disease caused by a wide range of variants. To explore this approach, a research team led by Dr Marulasiddappa Suresh from the University of Wisconsin studied two experimental vaccines that included compounds to specifically provoke a strong T-cell response in mice.

The team tested the vaccines’ ability to control infection and prevent severe disease caused by an earlier strain of SARS-CoV-2 as well as by the Beta variant, which is relatively resistant to antibodies raised against earlier strains.

When the researchers vaccinated the mice either either nasally or by injection, the animals developed T cells that could recognise the early SARS-CoV-2 strain and the Beta variant. The vaccines also caused the mice to develop antibodies that could neutralise the early strain. However, they failed to create antibodies that neutralised the Beta variant.

The mice were exposed to SARS-CoV-2 around 3 to 5 months after vaccination. Compared to the controls, vaccinated mice had very low levels of virus in their lungs and were protected against severe illness, which was true of infection with the Beta variant too. This showed that the vaccine provided protection against the Beta variant despite failing to produce effective antibodies against it.

To understand which T cells were providing this protection, the researchers selectively removed different types of T cells in vaccinated mice prior to infection. When they removed CD8 (killer) T cells, vaccinated mice remained well protected against the early strain, although not against the Beta variant. When they blocked CD4 T (helper) cells, levels of both the early strain and Beta variant in the lungs and severity of disease were substantially higher than in vaccinated mice that didn’t have their T cells removed.

These results suggest important roles for CD8 and CD4 T cells in controlling SARS-CoV-2 infection. Current mRNA vaccines do produce some T cells that recognize multiple variants. This may help account for part of the observed protection against severe disease from the Omicron variant. Future vaccines might be designed to specifically enhance this T cell response.

“I see the next generation of vaccines being able to provide immunity to current and future COVID variants by stimulating both broadly-neutralising antibodies and T cell immunity,” Dr Suresh predicted.

Source: National Institutes of Health

Categories : UncategorizedTags :

By Now, Nearly All South Africans Have COVID Antibodies

On By ModernMedia
South African flag with COVID theme
Image by Quicknews

The latest COVID seroprevalence survey shows that nearly every adult in South Africa has either been vaccinated or had COVID. For many, it’s both.

The study analysed blood from over 3000 blood donors. It was conducted by the South African National Blood Service, which is responsible for blood donations in eight provinces, and the Western Cape Blood Service.

The researchers estimated that by March 2022, before the fifth wave which appears to have peaked in the last few weeks, 98% of adults had some detectable antibodies, whether from COVID or from vaccination. This means that only 2% had neither been vaccinated nor been infected.

Only 10% had been vaccinated but not infected by COVID.

Read the study

(Note: The study has been published as a preprint and has not been peer-reviewed.)

What the survey tested for

Blood samples were collected and tested from 3395 consenting donors from all provinces in mid-March 2022. While blood donors are not precisely representative of the population, the researchers have argued that the study is representative enough.

This is the first time the blood services researchers have been able to look for two types of antibodies.

One test indicates if a sample has antibodies to the nucleocapsid proteins (anti-nucleocapsid antibodies). These antibodies develop if someone is infected, but won’t develop after a person receives a vaccine only (at least not those vaccines currently available in South Africa).

The other test indicates if the sample has antibodies to the spike protein (anti-spike antibodies). These antibodies develop when someone has been infected or has been vaccinated (or both).

Using these two tests together, researchers can, for the first time, evaluate the proportion of the population that has been vaccinated and not infected.

Results

After weighting the results to reflect national demographics, the researchers found that a mere 2% of the population had neither anti-spike nor anti-nucleocapsid antibodies. These are people who have likely never had COVID nor been vaccinated.

10% had only anti-spike antibodies. These are people who were likely vaccinated, but never infected.

The researchers noted that there is “an increasing incidence of reinfection” with the omicron wave.

Blood service survey is the best we have

The blood services have been regularly testing blood samples from donors throughout the pandemic, looking at the presence of anti-nucleocapsid antibodies.

While other surveys might be more representative of the population than the blood donor ones, these have been infrequently published or published long after the survey was conducted. By contrast the blood donor surveys are relatively affordable and quick to publish. Also, as far as we are aware, it is the only survey repeatedly testing the same group of people, so that comparisons across time are possible.

Past blood surveys

The blood services’ survey from samples taken in May 2021 estimated that 47% of the adult population had previously been infected.

The next survey of blood samples was taken in November 2021 after the delta wave. This was just before the omicron wave. The researchers estimated that about 70% of people had been infected.

The latest survey indicates that about 87% of people have been infected.

The previous surveys found that levels of infection differed by province. Now these differences have “largely disappeared as prevalence appears to have saturated”.

Differences across race

There are significant differences in rates of infection when different races are compared.

The November survey showed that about 80% of black donors and 40% of white donors had been infected with COVID.

In the latest survey the proportion of white and Asian donors that only have anti-spike antibodies (indicating vaccination but no infection) was higher than black and coloured donors.

The researchers suggest that “white donors are both unusually likely to avail themselves of vaccination, and they are unusually able to avoid exposure, for instance by working predominantly from home, [and] living in smaller family units.”

Article by By James Stent. Republished from GroundUp under a Creative Commons Attribution-NoDerivatives 4.0 International License.

Source: GroundUp