Immune response in SARS-CoV-1 survivors after COVID-19 vaccination

In a latest Cell Reports jouirnal research, researchers evaluated extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine-induced immune responses in SARS survivors.

Study: SARS-CoV-2 vaccine-induced antibody and T cell response in SARS-CoV-1 survivors. Image Credit: creativeneko / Shutterstock.com

Background

SARS-CoV-1, the causal agent of the 2002 epidemic, is a beta-CoV from the Coronaviridae household. SARS-CoV-1 an infection elicits humoral and mobile immune responses. Antibody responses might persist for 2 to 3 years post-infection, and particular reminiscence B-cells (MBCs) decline to undetectable ranges by six years.

In distinction, SARS-CoV-1 nucleocapsid (N)-specific reminiscence T-cell responses will be detected even after 17 years. These reminiscence T lymphocytes exhibit cross-reactivity with the SARS-CoV-2 N protein.

Mounting proof exhibits SARS-CoV-2-cross-reactive reminiscence T-cells in SARS-CoV-2-naïve people. Several reviews additionally point out cross-reactivity between SARS-CoV-2-specific T-cells and the T-cells particular for animal beta-CoVs and human frequent chilly CoVs.

One research famous that greater than 90% of wholesome adults have immunoglobulin G (IgG) particular to all human frequent chilly CoVs. However, whether or not coronavirus illness 2019 (COVID-19) vaccines enhance pre-existing cross-reactive reminiscence T-cell responses stay elusive.

Study findings

In the current research, researchers analyze SARS-CoV-2-specific antibody and T-cell responses after one dose of a COVID-19 vaccine (Ad5-nCoV) in those that survived an infection with SARS-CoV-1. A complete of 25 SARS survivors have been enrolled within the present research between June 2020 and July 2020.

Twenty research individuals obtained the Ad5-nCoV vaccine in July 2021. Additionally, three vaccinated survivors have been included within the research roughly six months after vaccination.

Further, 18 naïve wholesome people (NHIs) who obtained the Ad5-nCoV vaccine have been additionally enrolled within the present research. Ten cryopreserved specimens of peripheral blood mononuclear cells (PBMCs) and serum collected from wholesome donors earlier than September 2019 served as controls.

The researchers measured neutralizing antibody (nAb) ranges towards SARS-CoV-2 Wuhan-Hu-1 (WA), Alpha, Beta, Gamma, Delta, and Omicron variants.

Although most SARS-CoV-1 survivors had nAbs towards SARS-CoV-1, none had nAbs towards SARS-CoV-2 earlier than vaccination. After vaccination, 13 of those 23 survivors neutralized SARS-CoV-2 WA1; nonetheless, neutralization towards Omicron sub-variants BA.1, BA.2, BA.2.12.1, and BA.4/5 was attenuated. Nonetheless, nAb geometric imply titers (GMTs) have been increased towards SARS-CoV-1 than WA1.

One-third of NHIs had detectable nAbs towards WA1 after vaccination, with no important variations within the GMTs between SARS-CoV-2 WA1, variants, and SARS-CoV-1. Only Ad5-nCoV-vaccinated SARS-CoV-1 survivors had nAbs towards all examined viruses.

Because the antibody responses between vaccinated SARS survivors and NHIs have been comparable, the researchers investigated if the identical utilized to T-cell responses. To this finish, SARS-CoV-2 spike-specific T-cell responses have been decided utilizing intracellular cytokine staining (ICS), activation-induced marker (AIM), and enzyme-linked immunosorbent spot (ELISpot) assays.

The ELISpot assay confirmed comparable median ranges of SARS-CoV-2 spike-specific interferon-gamma (IFN-γ)-secreting T-cells post-vaccination in NHIs and SARS survivors, albeit considerably increased than wholesome controls.

All survivors and 16 NHIs had detectable ranges of IFN-γ-secreting spike-specific T-cells. SARS-CoV-2 spike-specific AIM⁺ cluster of differentiation 4-positive (CD4⁺) T-cells have been detected in 17 SARS survivors and 16 NHIs, with comparable median frequencies however considerably increased than controls. The researchers noticed the same sample of SARS-CoV-2 spike-specific AIM⁺ CD8⁺ T-cells.

The ICS assay revealed the presence of SARS-CoV-2 spike-specific IFN-γ⁺ CD4⁺ T cells in 75% of SARS survivors and 66% of NHIs, with considerably increased median frequencies than controls. Similarly, 80% of SARS-CoV-1 survivors and 38.1% of NHIs had detectable spike-specific IFN-γ⁺ CD8⁺ T-cells. SARS-CoV-1 survivors had considerably increased frequencies than controls, whereas NHIs and controls had comparable frequencies.

Lastly, the authors assessed if Ad5-nCoV vaccination would lead to extra sturdy and potent SARS-CoV-1-specific T-cell responses in SARS-CoV-1 survivors. Taken collectively, 81% of SARS survivors and 40% of NHIs had SARS-CoV-1 spike-specific IFN-γ-secreting T-cells, as measured by an ELISpot assay.

More than 80% of SARS-CoV-1 survivors had SARS-CoV-1 spike-specific AIM⁺ CD4⁺ and CD8⁺ T-cells and IFN-γ⁺ CD4⁺ T-cells, whereas roughly 60% of SARS-CoV-1 survivors had detectable IFN-γ⁺ CD8⁺ T-cells.

Conclusions

Ad5-nCoV vaccination in SARS-CoV-1 survivors boosted nAbs towards SARS-CoV-1 however had decrease magnitude and ranges of nAbs towards SARS-CoV-2. Nonetheless, vaccination in SARS-CoV-1 survivors and NHIs induced particular T-cell responses towards SARS-CoV-2 variants six months post-vaccination, thus suggesting that vaccination is insufficient to boost the breadth and lifetime of SARS-CoV-2-specific antibody responses however results in protracted T-cell response.

Taken collectively, the research findings indicated that SARS-CoV-1 survivors and NHIs have comparable T-cell and antibody responses towards SARS-CoV-2 after vaccination.