Moderna and Pfizer-BioNTech vaccines induce a strong T cell response to SARS-CoV-2 mutants

Researchers in the United States Effectiveness of Moderna and Pfizer-BioNTech vaccines elicit a potent T-cell response to drug variants that cause severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) – coronavirus disease 2019 (COVID-19) I will.

Teams from the Gladstone Virology Institute in San Francisco and the University of California have also evidenced that individuals who received one vaccination after recovering from SARS-CoV-2 infection may not need a second dose. Provided.

In addition, Nadia Roan et al. Found that vaccination in previously infected individuals may result in more sustained homing of SARS-CoV-2 specific T cells into the respiratory tract than in previously uninfected individuals. Was shown.

“We have found a reassuring, unchanged T cell response to mutants and a significant effect of previous infections on vaccination-induced T cell qualitative characteristics,” the team wrote.

The preprinted version of the research treatise is bioRxiv* Servers and articles have been peer reviewed.

Concerns about vaccine efficacy against mutants

Since the outbreak of COVID-19 first began in late December 2019, due to the development of vaccines against SARS-CoV-2 and enthusiastic efforts in clinical trials, emergency use authorization for several mRNA-based vaccines was soon granted. Was obtained.

Pfizer-BioNTech and Moderna vaccines have proven to be very effective in protecting against SARS-CoV-2 infections, but are concerned about the extent to which they can protect against new variants that are currently spreading rapidly around the world. Is occurring.

Antibodies generated after vaccination generally remain potent against the B.1.1.7 mutant that emerged in the United Kingdom, as well as against the SARS-CoV-2 ancestral strain. However, studies have also shown that the antibody is less effective against the B.1.351 strain that emerged in South Africa and the P.1 mutant that emerged in Brazil.

It is also unclear how booster doses and previous infections affect vaccine-induced immunity.

T-cell-mediated immunity seems difficult to avoid

Encouragingly, early studies suggest that T-cell-mediated immunity appears less prone to avoidance by mutants.

“The relative resistance of T cells to SARS-CoV-2 antigenic escape is important in light of the important role these immune effectors play in COVID-19,” Roan et al. “T cell numbers are strongly inversely associated with disease severity, and SARS-CoV-2 specific T cell frequency predicts recovery from severe disease.”

The team adds that T cells can be key to long-term immunological memory because they have the ability to last for decades.

In addition, studies of antibody-B cell responses to infection suggest that a single dose of mRNA vaccine may be beneficial during the COVID-19 convalescent phase, but a second booster jab is not required.

However, “it is not clear how this is interpreted in the context of vaccine-induced T cell immunity,” Roan et al.

What did the researchers do?

The team conducted a longitudinal study of eight mRNA-vaccinated individuals. Four of them recovered from COVID-19 and four had no history of infection. The researchers performed T cell-centric CyTOF (time-of-flight cytometry) analysis on SARS-CoV-2 specific T cells in phenotypic participants.

Three of the participants were vaccinated with the Modern RNA-1273 vaccine and the remaining five were vaccinated with the Pfizer-BioNTech BNT162b2 vaccine.

For each of the 24 samples obtained, researchers evaluated T cell phenotype and effector function in response to. Spike protein Comparison of spikes between the original SARS-CoV-2 strain and the B.1.1.7 (UK) and B.1.351 (South Africa) mutants.

Peplomers are the major structure that viruses use to infect host cells. Neutralizing antibody After vaccination.

What did they find?

Vaccinated T cells responded similarly to spike epitopes from ancestral strains and mutants. The phenotypic characteristics of these cells were identical among the different strains.

“The fact that both the quantity and quality of the T cell response are maintained against the mutant may provide an explanation for the actual efficacy of the vaccine against the mutant,” the team says.

In individuals without a history of infection, the dose increased with the second dose, although not with the quality of the spike-specific response...

Researchers say this emphasizes the importance of ensuring a second dose to individuals who have never been infected.

However, there was no evidence of spike-specific T cell phenotypic changes after the second dose among convalescent participants, but no evidence of increased T cell numbers.

“Our results suggest that a second SARS-CoV-2 vaccination of an individual who has recovered from COVID-19 may be less beneficial than an individual who has never been previously exposed to SARS-CoV-2. It suggests that there is, “Roen et al.

Phenotypic differences between convalescent vaccinated and uninfected vaccinated

Researchers say one of the most striking findings was a significantly different phenotype of spike-specific T cells between convalescent and non-infectious disease vaccinated individuals.

Spike-specific CD4 + T cells from convalescent individuals showed increased potential for long-term persistence, including increased expression of CD127, a marker for long-lived memory T cells.

Compared to uninfected vaccinated individuals, CD4 + T cells from the nasopharynx of the upper respiratory tract of convalescent individuals also expressed multiple tissue homing receptors.

What is the meaning of research?

“In summary, these results indicate that convalescent spike-specific CD4 + T cells may be superior in survival and airway migration compared to individuals without a history of infection.” The researchers write.

With reference to the overall findings, the team said: Vaccinated convalescent patients may have more persistent nasopharyngeal homing SARS-CoV-2 specific T cells than convalescent patients without infection.

*Important Notices

bioRxiv Publish preliminary scientific reports that should not be considered definitive as they are not peer-reviewed, guide clinical practice / health-related behaviors, and should not be treated as established information.