Category: Immunology

Categories : COVID ImmunologyTags :

New “Double Antibodies” can Treat COVID Variants

On By ModernMedia

A new generation of “double antibodies” has been developed which can protect against all SARS-CoV-2 variants, as well as inhibiting mutations against the antibodies.

These “bispecific”  antibodies were created by the Institute for Research in Biomedicine (IRB; Bellinzona, Switzerland), which is affiliated to the Università della Svizzera italiana (USI).

While traditional antibody-based immunisation is able to offer protection against SARS-CoV-2, there is still a need to protect against variants which may achieve “vaccine escape”, as well as inhibiting mutations which give rise to resistance, as with antibiotic resistance in bacteria.

The researchers overcame these difficulties by splicing together a pair of antibodies to make a “bispecific” antibody that simultaneously targets two viral sites. The bispecific antibody treatment has proved effective in mouse models, which maintained body weight when infected with SARS-CoV-2, compared to infected controls, which lost 20-30% body weight before humane euthanisation. The paper is available on the bioRxiv preprint server.

Study author Luca Varani of USI explained: “We exploited our knowledge of the molecular structure and biochemical traits of the virus to fuse together two human antibodies, obtaining a single bispecific molecule simultaneously attacking the virus in two independent sites critical for infectivity. Supercomputing simulations allowed us to refine and validate the bispecific antibody design, which was later produced and tested in the laboratory. Although the virus can mutate and escape from the attack of a single first-generation antibody, we have shown that it cannot do so against the double action of the bispecific.

“A single injection of the bispecific antibody provides instantaneous protection against the disease in pre-clinical trials. The antibody effectively reduces viral burden in the lungs and mitigates inflammation typical of COVID-19”, said Daniel Ruzek from the Czech Academy of Sciences who led the antibody pre-clinical testing.

The effectiveness of the bispecific antibodies holds promise for human clinical trials, with the prospect of being both an effective prevention and treatment of COVID.

Source: News-Medical.Net

Journal information: Gasparo, R D., et al. (2020) Bispecific antibody prevents SARS-CoV-2 escape and protects mice from disease. bioRxiv.doi.org/10.1101/2021.01.22.427567.

Categories : Diseases, Syndromes and Conditions Gastrointestinal ImmunologyTags :

Taurine Boosts Microbiotic Defences in the Gut

On By ModernMedia

A new study has discovered that taurine has a role in triggering the gut’s microbiota to identify and destroy invading bacteria, such as Klebsiella pneumoniae, a bacteria commonly found in the gut and responsible for a variety of infections.

It is already known that gut microbiota can protect against infection, but it is not well understood how they accomplish this. A better of understanding of how they confer protection will aid the development of replacements for current antibiotic drugs, which currently harm gut microbiota and whose effectiveness is waning.

Taurine is a complementary (non-essential amino acid, involved in helping break down fats and is present in bile acid. Most taurine is produced by the body but some is also required in the diet. Certain seafoods, seaweed, poultry and beef are good sources of taurine.

The scientists believed that the taurine helped prevent against bacterial colonisation by producing hydrogen sulphide, but during their research they also discovered that a single infection was sufficient to prepare the gut microbiota to resist a second infection. The liver and gallbladder which produce and store bile acids, can develop long-term protection against infection.

While investigating further, the researchers discovered a particular type of bacteria, Deltaproteobacteria, which protected the gut against colonisation by infectious bacteria and which was activated by taurine. Taurine fed to mice in drinking water helped to shield against infection by boosting the function of the protective bacteria, but those fed bismuth subsalicylate (a common over-the-counter diarrhoea treatment), the infection protection diminished, because bismuth suppresses hydrogen sulphide production in the gut.

Source: News-Medical.Net

Categories : HIV ImmunologyTags :

HIV Vaccine Search is a Marathon

On By ModernMedia

While COVID vaccines have appeared in a record-breaking short time, an HIV vaccine is still yet to arrive – though not without good reasons, as The Daily Maverick reports.

Mitchell Warren, executive director of AVAC, a US-based HIV advocacy organisation explained: “There is still no conclusive research on what type of immune response an HIV vaccine should be trying to trigger.”

“With HIV, you’re trying to do better than nature,” continued Warren. “With a Covid-19 vaccine, the jab merely has to do what nature is doing already — in the form of an immune response — just faster. But with HIV, you’re trying to do better than nature because your body isn’t able to successfully fight off the virus.”

HIV mutates quite rapidly, to the point where there are now two distinct strains, HIV-1 and HIV-1, complicating the process. SARS-CoV-2 on the other hand uses a process called proofreading when it replicates, ensuring a lower rate of mutations.

There are currently three vaccines in development; HPX2008/HVTN 705: Imbokodo and HPX3002/HVTN 706: Mosaico both use adenoviruses to deliver protein fragments of the HIV virus to train the immune system to respond to it. The “Imbokodo” is being trialled with young women, and “Mosaico” is being trialled with transgender men and men who have sex with men, and expected to end in 2022 and 2024 respectively. 

The PrEPVacc vaccine uses DNA inserted into plasmids, which induce the body to produce the virus’ proteins, but not the virus itself. The two shots contain a cocktail of proteins and the plasmids to train the immune system. The trial is expected to end in 2023

Categories : ImmunologyTags :

Gut Microbiota Have Large Effects on Immune System

On By ModernMedia

For the first time, immune cells in the bloodstream have been shown to be affected by the makeup of gut microbiota.

In recent years, there has been increased interest in gut microorganisms and their influence on human health, partly as a result of improvements in the ability to study them. Much prior understanding of gut microbiota on the immune system comes from animal studies; this study was able to examine the effects in humans. This study used data from allogeneic stem cell and bone marrow transplants (BMTs), where the patient’s blood formation system is destroyed by radiation or chemotherapy and replaced with stem cells from a donor’s bone marrow. The patient is given antibiotics until the transplanted cells are able to re-establish the immune system, the gut microbiota being destroyed in the process and then re-establishing once the antibiotics are withdrawn. Over a period of ten years, a multidisciplinary team with the Memorial Sloan Kettering Cancer Center took blood and faecal samples from BMT patients.

Study author Dr Joao Xavier said, “Our study shows that we can learn a lot from stool—biological samples that literally would be flushed down the toilet. The result of collecting them is that we have a unique dataset with thousands of datapoints that we can use to ask questions about the dynamics of this relationship.”
“The parallel recoveries of the immune system and the microbiota, both of which are damaged and then restored, gives us a unique opportunity to analyse the associations between these two systems,” lead author Dr Jonas Schluter said.

A higher diversity of microbiota was shown to lower the risk of death following a BMT, and a lower diversity increased the risk of graft-versus-host disease, a potentially fatal condition where the transplanted marrow attacks the host’s body.

“Because experiments with people are often impossible, we are left with what we can observe,” Dr. Schluter noted. “But because we have so many data collected over a period of time when the immune system of patients as well as the microbiome shift dramatically, we can start to see patterns. This gives us a good start toward understanding the forces that the microbiota exerts on the rebuilding of the immune system.”

Source: Medical Xpress

Journal information: Jonas Schluter et al. The gut microbiota is associated with immune cell dynamics in humans, Nature (2020). DOI: 10.1038/s41586-020-2971-8