The impact of CMV serostatus on humoral and mobile measures of vaccine responses after 2 and three doses of SARS-CoV-2 mRNA vaccines in older adults
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In a latest examine posted to the medRxiv* preprint server, researchers evaluated the impression of cytomegalovirus (CMV) seropositivity on humoral and mobile immune responses generated after double and/or triple messenger ribonucleic acid (mRNA) vaccination towards extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among the many aged.

Study: CMV seropositivity in older adults adjustments T cell performance, however doesn’t stop antibody or mobile SARS-CoV-2 vaccine responses. Image Credit: Rido/Shutterstock

CMV seropositivity has been related to decreased humoral immune responses to Ebola vaccines and influenza vaccines. On the opposite, mobile or humoral immune responses induced by ChAdOx1 nCoV-19 vaccination amongst younger adults have been reported to be unaffected by CMV serostatus. Therefore, information on the impression of CMV seropositivity on host antiviral immune responses has conflicting outcomes. Moreover, the impression of CMV serostatus on SARS-CoV-2 mRNA vaccine-induced immunity is but unknown.

About the examine

In the current examine, researchers evaluated the consequences of CMV serostatus on humoral and mobile immune responses after two and three doses of SARS-CoV-2 mRNA vaccines (mRNA-1273 or BNT162b2) amongst elder people residing in assisted dwelling services.

The examine was performed between March and December 2021 on 188 people aged ≥65 years who resided in congregate dwelling services (14 nursing houses and three retirement houses) in Ontario, Canada. Blood samples have been collected from all individuals a minimal of 1 week after both the second dose or after the third dose of mRNA vaccines. For 47 individuals, blood samples have been obtained after double and triple mRNA vaccination.

CMV seropositivity was assessed by evaluating the anti-CMV immunoglobulin G (IgG) titers utilizing enzyme-linked immunosorbent assays (ELISA). The impression of CMV seropositivity on humoral immune responses after SARS-CoV-2 vaccination was decided based mostly on the impact of CMV seropositivity on the anti-SARS-CoV-2 spike (S) antibody titers and anti-SARS-CoV-2 receptor-binding area (RBD) immunoglobulin G (IgG), IgA, and IgM titers. In addition, the neutralization capability of antibodies towards SARS-CoV-2 wildtype and Beta strains was assessed utilizing cell tradition assays with Vero E6 cells.

Immunophenotyping assays and stream cytometry evaluation have been carried out to determine 5 subsets of T lymphocytes as follows: naïve (N), terminally differentiated (TD), central reminiscence (CM), effector reminiscence (EM), effector reminiscence re-expressing CD45RA (EMRA) lymphocytes. Subsets of the cluster of differentiation 4 constructive (CD4+) T lymphocytes corresponding to T helper 1 (Th1), Th2, and Th17 have been recognized based mostly on their C-C chemokine receptor sort 4 (CCR4), CCR6, and chemokine receptor 3 (CXCR3) expression. In addition, absolutely the T lymphocyte counts have been decided.  

Further, T lymphocyte activation assays have been carried out to determine activation-induced marker (AIM)-positive and antigen-specific T lymphocytes based mostly on the CD25 and CD134 co-expression on CD4+ T lymphocytes and CD69 and CD137 co-expression on CD8+ T lymphocytes. In addition, recall (reminiscence) responses of AIM+ cells have been assessed utilizing the SARS-CoV-2 S peptide pool.

The impression of CMV seropositivity on COVID-19 incidence and the impact of prior SARS-CoV-2 infections on the antibody-mediated humoral immune responses and T lymphocyte-mediated mobile immune responses have been assessed. Prior SARS-CoV-2 an infection was recognized based mostly on constructive polymerase chain response (PCR) experiences or seropositivity for IgA or IgG nucleocapsid antibodies.


Of 188 individuals, 131 (69.7%) individuals demonstrated CMV seropositivity. Five to seven months after double mRNA vaccination, anti-S IgG and anti-RBD IgG titers have been detected in 89% and 64% of individuals, respectively, which elevated to 97% and 95% three months after triple mRNA vaccination, respectively. CMV seropositive and seronegative individuals demonstrated comparable neutralization capability towards the wildtype and Beta strains. Moderate correlations have been noticed between the anti-S, anti-RBD IgG, and anti-RBD IgA titers and the neutralization capability, regardless of CMV serostatus. This indicated that CMV seropositivity didn’t have an effect on mRNA vaccine-induced anti-SARS-CoV-2 humoral immunity.

In the stream cytometry evaluation, CMV serostatus didn’t considerably alter the counts of complete CD4+ T lymphocytes, or CD4N, CD4EM, CD8N, or CD8EM T lymphocytes. However, elevated complete CD8+ T lymphocytes and CD4EMRA, CD4TD, CD8EMRA, and CD8TD T lymphocyte counts and decreased CD4CM and CD8CM T lymphocyte counts have been noticed amongst CMV seropositive individuals.

T lymphocyte activation assays confirmed that CMV seropositivity decreased CD28 expression on CD8CM and CD8EM lymphocytes; nevertheless, CMV serostatus didn’t have an effect on CD57 or CD28 expression on CD4N T lymphocytes. CMV serostatus was related to elevated CD8+ T lymphocyte expression. Still, it didn’t improve CD4+ T lymphocyte recall responses towards SARS-CoV-2 S. CMV serostatus considerably impacted Th1 S-CD4+ T lymphocyte frequency however not Th17 S- and Th2 S-CD4+ T lymphocyte frequencies. In addition, CMV serostatus didn’t have an effect on the variety of people with SARS-CoV-2 S-activated CD4+ T lymphocytes or CD8+ T lymphocytes after double or triple mRNA vaccinations.

Further, CMV seropositivity elevated AIM+ CD8+ T lymphocyte counts however not AIM+CD4+ T lymphocyte frequency. CMV serostatus altered reminiscence T lymphocyte purposeful composition, with SARS-CoV-2 S-targeted results; nevertheless, there was no change within the capability to generate CD4+ or CD8+ T lymphocyte reminiscence COVID-19 incidence after mRNA vaccination was noticed amongst CMV seropositive elders.

Overall, the examine findings confirmed that CMV seropositivity could alter T lymphocyte composition however doesn’t impede mobile or humoral immune responses after mRNA vaccinations within the aged.

*Important discover

medRxiv publishes preliminary scientific experiences that aren’t peer-reviewed and, due to this fact, shouldn’t be considered conclusive, information medical apply/health-related habits, or handled as established info.

Journal reference:

  • Breznik, J. et al. (2022) “CMV seropositivity in older adults changes T cell functionality, but does not prevent antibody or cellular SARS-CoV-2 vaccine responses”. medRxiv. doi: 10.1101/2022.05.27.22275673. material/10.1101/2022.05.27.22275673v1

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