This National Institute of Allergy and Infectious Disease(NIAID) handout photo obtained March 30, 2021 shows a scanning electron micrograph of a human T lymphocyte (also called a T cell) from the immune system of a healthy donor Photo: National Institute of Allergy and Infectious Diseases/AFP
health

Killer T cells boost immunity to coronavirus variants: study

10 Comments

The emergence of coronavirus variants has provoked concern about their impact on the effectiveness of vaccines, and whether people who were previously infected might be more susceptible to reinfection.

But in welcome news, a new study this week showed that a key player in the immune response, called the "killer T cell," remained mostly unaffected.

The finding is encouraging because although these white blood cells are not a first line defense against infection, they can help prevent severe disease.

Scientists at the National Institutes of Health and Johns Hopkins University analyzed blood samples from 30 people who had contracted and recovered from COVID-19 prior to the emergence of variants.

They published their findings in Open Forum Infectious Diseases, an Oxford University Press journal.

The team wanted to know whether these cells, known by their technical name "CD8+ T cells," could still recognize three variants of SARS-CoV-2: B.1.1.7, first found in Britain, B.1.351, identified in South Africa, and B.1.1.248, first seen in Brazil.

What makes each of these variants unique is the mutations they carry, especially in a region of the virus' spike protein, structures that stud its surface and allow it to invade cells.

It has already been shown that mutations to this region of the spike protein make some variants less recognizable to neutralizing antibodies -- infection fighting proteins produced by the immune system's B cells.

This seems to be particularly true, for instance, of B.1.351, according to research on the impact of current generation Covid vaccines.

Neutralizing antibodies are custom-made to fit an antigen, or a specific structure of a pathogen.

In the case of the coronavirus, this is the spike protein, which the antibodies bind to, preventing the virus from infecting cells.

Killer T cells, on the other hand, look for telltale signs of cells that have already been infected with pathogens they have previously encountered, and then kill those cells.

In the new study, the researchers found that the killer T cell responses remained largely intact and could recognize virtually all mutations in the variants studied.

The researchers noted that larger studies are needed to confirm the results, but said that it nevertheless demonstrated that killer T cells are less susceptible to mutations in the coronavirus than neutralizing antibodies are.

Antibodies are still important to prevent infection in the first place -- and the reduced efficacy of vaccines to the variants seems to be evidence of this.

But a killer T cell response that kicks in later and aids in clearing off the disease, helps explain why the vaccines seem to be able to prevent severe disease and hospitalization, even though their efficacy at stopping infection by variants is reduced.

© 2021 AFP

©2021 GPlusMedia Inc.

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This is of course hardly surprising, since the first few months it was known that antibody levels dropped relatively fast, specially on less symptomatic infections, but the people were still protected against reinfections (and continue to be after a year) which made the experts think that cellular immunity was the responsible for this protection.

Since cellular mediated protection is much more elaborate viruses have a much harder time avoiding it, the person can still be technically "re-infected" if the antibodies fail to neutralize the variants immediately, but as long as the T-cells can recognize the virus the symptoms can be reduced or avoided completely.

The problem is that evaluating the activity of the T-cells is a much more complicated and expensive process, which is why until now tests for immunity are based on antibodies. This is what makes it difficult to see how well protected people are.

1 ( +3 / -2 )

Imagine that, we've just discovered humans have their own immune system that naturally works against the coronavirus

Oh sorry actually we knew all of this based on accepted science: https://pubmed.ncbi.nlm.nih.gov/32758887/

-1 ( +3 / -4 )

I've been listening to some interviews of Geert Vanden Bossche.

He explains that Killer T cells are indeed very important and that they get better with regular exposure to pathogens and weaker if not exposed (social distancing/constant mask wearing).

He also explains how taking the covid vaccines can adversely affect the Killer T cells' ability to fight infections.

Of course big pharma does not like his comments, so if you google his name you will get countless sites attacking or "debunking" him, but I do recommend everyone at least give his videos a listen.

He's a vaccine expert and is clearly not an anti-vaxxer, see his background here:

https://be.linkedin.com/in/geertvandenbossche?src=aff-lilpar&veh=aff_src.aff-lilpar_c.partners_pkw.123201_plc.adgoal%20GmbH_pcrid.449670_learning&trk=aff_src.aff-lilpar_c.partners_pkw.123201_plc.adgoal%20GmbH_pcrid.449670_learning&clickid=1tnXCo14KxyJRSO0ElylqXhuUkEXZ62X1wBkzE0&irgwc=1

-2 ( +2 / -4 )

He explains that Killer T cells are indeed very important and that they get better with regular exposure to pathogens and weaker if not exposed (social distancing/constant mask wearing).

He also explains how taking the covid vaccines can adversely affect the Killer T cells' ability to fight infections.

Again, the problem with these kind of explanations is that they lack even the minimum amount of evidence to back them up, wild imaginations that fail to explain what actually happens in reality are the worst kind of references you can find.

Of course big pharma does not like his comments, so if you google his name you will get countless sites attacking or "debunking" him

Nope, "Big pharma" would love for him to be right, so instead of dirt cheap vaccines they could keep profiting from people spending thousands over thousands of dollars on hospitalizations and treatment for long COVID. The one that do not like his comments is the scientific community, that validly consider him a quack that likes to misrepresent evidence and jump to invalid conclusions while trying to pretend to be scientific about it, he is not.

https://www.mcgill.ca/oss/article/covid-19-critical-thinking-pseudoscience/doomsday-prophecy-dr-geert-vanden-bossche

He's a vaccine expert and is clearly not an anti-vaxxer, see his background here:

Again with the invalid appeal to authority, the actually important part is not what he is but what he needs to prove his personal opinions as right, and this is evidence. His qualifications only make it worse for him to be mistaken because he should know better than conclude things in abscense of evidence, or even in spite of evidence that proves the contrary.

1 ( +4 / -3 )

virusrexToday  11:13 am JST

He explains that Killer T cells are indeed very important and that they get better with regular exposure to pathogens and weaker if not exposed (social distancing/constant mask wearing).

He also explains how taking the covid vaccines can adversely affect the Killer T cells' ability to fight infections.

Again, the problem with these kind of explanations is that they lack even the minimum amount of evidence to back them up, wild imaginations that fail to explain what actually happens in reality are the worst kind of references you can find.

Of course big pharma does not like his comments, so if you google his name you will get countless sites attacking or "debunking" him

Nope, "Big pharma" would love for him to be right, so instead of dirt cheap vaccines they could keep profiting from people spending thousands over thousands of dollars on hospitalizations and treatment for long COVID. The one that do not like his comments is the scientific community, that validly consider him a quack that likes to misrepresent evidence and jump to invalid conclusions while trying to pretend to be scientific about it, he is not.

https://www.mcgill.ca/oss/article/covid-19-critical-thinking-pseudoscience/doomsday-prophecy-dr-geert-vanden-bossche

He's a vaccine expert and is clearly not an anti-vaxxer, see his background here:

Again with the invalid appeal to authority, the actually important part is not what he is but what he needs to prove his personal opinions as right, and this is evidence. His qualifications only make it worse for him to be mistaken because he should know better than conclude things in abscense of evidence, or even in spite of evidence that proves the contrary.

0 ( +2 / -2 )

I've been listening to some interviews of Geert Vanden Bossche.

Hope his ideas are sounder than the people who convinced you this virus had burned itself out last year.

2 ( +4 / -2 )

Personally, I don’t see a dramatic gain or advantage. Assumed, someone is strongly infected with a massive corona virus load and the viruses are affecting multiple organs, not only the lung, then those T-cells would attack plenty of own cells or whole regions, leading to an even faster death, then caused by own T-cells and not so very much by the corona virus itself.

-1 ( +0 / -1 )

Bossche's website is also quite good, he has a number of reports with plenty of references: https://www.geertvandenbossche.org/

He is clearly knows a lot about vaccines and immunology.

Clearly more convincing than something written by a guy with a Masters at the Office of Science and Society, written in the usual deceptive hit-piece style. Not the first time virusrex uses that as a source.

@Gooch, you pasted virusrex's entire post, but it seems you forgot to add any comment. I'd love to know your thoughts on it.

-2 ( +1 / -3 )

He is clearly knows a lot about vaccines and immunology

Unfortunately he appears not to know enough to sustain his opinions with evidence, which would make his motives suspicious. It is not believable that a professional "fortets" to do the first thing that is taught to students, that usually indicates the conclusions he likes are not valid so he is reduced to do an invalid appeal to authority.

An elementary student with evidence wins over a Nobel prize without it, conspiracy fans always fail to understand how science works and think a title can replace evidence, that is false.

0 ( +2 / -2 )

On a related note, the news so far is that the three vaccines that have been approved by the CDC have all been shown to be effective against the variants. That is very good news.

1 ( +1 / -0 )

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