Additional heterologous versus homologous booster vaccination in immunosuppressed patients without SARS-CoV-2 antibody seroconversion after primary mRNA vaccination: a randomised controlled trial

ObjectivesSARS‐CoV‐2-induced COVID-19 has led to exponentially rising mortality, particularly in immunosuppressed patients, who inadequately respond to conventional COVID-19 vaccination.MethodsIn this blinded randomised clinical trial, we compare the efficacy and safety of an additional booster vaccination with a vector versus mRNA vaccine in non-seroconverted patients. We assigned 60 patients under rituximab treatment, who did not seroconvert after their primary mRNA vaccination with either BNT162b2 (Pfizer–BioNTech) or mRNA-1273 (Moderna), to receive a third dose, either using the same mRNA or the vector vaccine ChAdOx1 nCoV-19 (Oxford–AstraZeneca). Patients were stratified according to the presence of peripheral B cells. The primary efficacy endpoint was the difference in the SARS-CoV-2 antibody seroconversion rate between vector (heterologous) and mRNA (homologous) vaccinated patients by week 4. Key secondary endpoints included the overall seroconversion and cellular immune response; safety was assessed at week 1 and week 4.ResultsSeroconversion rates at week 4 were comparable between vector (6/27 patients, 22%) and mRNA (9/28, 32%) vaccines (p=0.6). Overall, 27% of patients seroconverted; specific T cell responses were observed in 20/20 (100%) vector versus 13/16 (81%) mRNA vaccinated patients. Newly induced humoral and/or cellular responses occurred in 9/11 (82%) patients. 3/37 (8%) of patients without and 12/18 (67%) of the patients with detectable peripheral B cells seroconverted. No serious adverse events, related to immunisation, were observed.ConclusionsThis enhanced humoral and/or cellular immune response supports an additional booster vaccination in non-seroconverted patients irrespective of a heterologous or homologous vaccination regimen.

Immunosequencing and epitope mapping reveal substantial preservation of the T cell immune response to Omicron generated by SARS-CoV-2 vaccines

The Omicron SARS-CoV-2 variant contains 34 mutations in the spike gene likely impacting protective efficacy from vaccines. We evaluated the potential impact of these mutations on the cellular immune response. Combining epitope mapping to SARS-CoV-2 vaccines that we have determined from past experiments along with T cell receptor (TCR) repertoire sequencing from thousands of vaccinated or naturally infected individuals, we estimate the abrogation of the cellular immune response in Omicron. Although 20% of CD4+ T cell epitopes are potentially affected, the loss of immunity mediated by CD4+ T cells is estimated to be slightly above 30% as some of the affected epitopes are relatively more immunogenic. For CD8+ T cells, we estimate a loss of approximately 20%. These reductions in T cell immunity are substantially larger than observed in other widely distributed variants. Combined with the expected substantial loss of neutralization from antibodies, the overall protection provided by SARS-CoV-2 vaccines could be impacted adversely. From analysis of prior variants, the efficacy of vaccines against symptomatic infection has been largely maintained and is strongly correlated with the T cell response but not as strongly with the neutralizing antibody response. We expect the remaining 70% to 80% of on-target T cells induced by SARS-CoV-2 vaccination to reduce morbidity and mortality from infection with Omicron.

Persistence of immune response in health care workers after two doses BNT162b2 in a longitudinal observational study

Background The mRNA-based vaccine BNT162b2 of BioNTech/Pfizer has shown high efficacy against SARS-CoV-2 infection and a severe course of the COVID-19 disease. However, little is known about the long-term durability of the induced immune response resulting from the vaccination. Methods In a longitudinal observational study in employees at a German hospital we compared the humoral and cellular immune response in 184 participants after two doses of the BioNTech/Pfizer vaccine (BNT162b2) with a mid-term follow-up after 9 months. Anti-SARS-CoV-2 binding antibodies were determined using both a quantitative and a semi-quantitative assay. For a qualitative assessment of the humoral immune response, we additionally measured neutralizing antibodies. Cellular immune response was evaluated by measuring Interferon-gamma release after stimulating blood-cells with SARS-CoV-2 specific peptides using a commercial assay. Results In the first analysis, a 100% humoral response rate was described after two doses of BNT162b2 vaccine with a mean antibody ratio of 8.01 ± 1.00. 9 months after the second dose of BNT162b2, serological testing showed a significant decreased mean antibody ratio of 3.84 ± 1.69 (p < 0.001). Neutralizing antibodies were still detectable in 96% of all participants, showing an average binding inhibition value of 68.20% ± 18.87%. Older age, (p < 0.001) and obesity (p = 0.01) had a negative effect on the antibody persistence. SARS-CoV-2 specific cellular immune response was proven in 75% of individuals (mean IFN-gamma release: 579.68 mlU/ml ± 705.56 mlU/ml). Conclusion Our data shows a declining immune response 9 months after the second dose of BNT162b2, supporting the potentially beneficial effect of booster vaccinations, the negative effect of obesity and age stresses the need of booster doses especially in these groups.

Ubiquitinated Hepatitis D Antigen-Loaded Microvesicles Induce a Potent Specific Cellular Immune Response to Inhibit HDV Replication in Vivo

Hepatitis D is the most severe viral hepatitis with accelerating the process of liver cirrhosis and increasing the risk of hepatocellular carcinoma. However, there are no effective antiviral drugs.

The Evaluation of Cellular Immunity to Avian Viral Diseases: Methods, Applications, and Challenges

Cellular immune responses play critical roles in the control of viral infection. However, the immune protection against avian viral diseases (AVDs), a major challenge to poultry industry, is yet mainly evaluated by measuring humoral immune response though antibody-independent immune protection was increasingly evident in the development of vaccines against some of these diseases. The evaluation of cellular immune response to avian viral infection has long been neglected due to limited reagents and methods. Recently, with the availability of more immunological reagents and validated approaches, the evaluation of cellular immunity has become feasible and necessary for AVD. Herein, we reviewed the methods used for evaluating T cell immunity in chickens following infection or vaccination, which are involved in the definition of different cellular subset, the analysis of T cell activation, proliferation and cytokine secretion, and in vitro culture of antigen-presenting cells (APC) and T cells. The pros and cons of each method were discussed, and potential future directions to enhance the studies of avian cellular immunity were suggested. The methodological improvement and standardization in analyzing cellular immune response in birds after viral infection or vaccination would facilitate the dissection of mechanism of immune protection and the development of novel vaccines and therapeutics against AVD.

Predicted Epitope Abundance Supports Vaccine-Induced Cytotoxic Protection Against SARS-CoV-2 Variants of Concern

The effect of emerging SARS-CoV-2 variants on vaccine efficacy is of critical importance. In this study, the potential impact of mutations that facilitate escape from the cytotoxic cellular immune response in these new virus variants for the 551 most abundant HLA class I alleles was analyzed. Computational prediction showed that most of these alleles, that cover &gt;90% of the population, contain enough epitopes without escape mutations in the principal SARS-CoV-2 variants. These data suggest that the cytotoxic cellular immune protection elicited by vaccination is not greatly affected by emerging SARS-CoV-2 variants.

Infection in asymptomatic carriers of SARS-CoV-2 can interfere with the achievement of robust immunity on a population scale

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to spread worldwide as a severe pandemic, and a significant portion of the infected population may remain asymptomatic. Given this, five surveys were carried out between May and September 2020 with a total of 3585 volunteers in the municipality of Foz do Iguaçu, State of Paraná, a triple border region between Brazil/Argentina/Paraguay. Five months after the first infection, volunteers were re-analysed for the production of IgG anti-Spike and anti-RBD-Spike, in addition to analyses of cellular immunity. Seroconversion rates ranged from 4.4 % to a peak of 37.21 % followed by a reduction in seroconversion to 21.1 % in September, indicating that 25 % of the population lost their circulating anti-SARS-CoV-2 antibodies 3 months after infection. Analyses after 5 months of infection showed that only 17.2 % of people still had anti-RBD-Spike antibodies, however, most volunteers had some degree of cellular immune response. The strategy of letting people become naturally infected with SARS-CoV-2 to achieve herd immunity is flawed, and the first contact with the virus may not generate enough immunogenic stimulus to prevent a possible second infection.

How Dopamine Influences Survival and Cellular Immune Response of Rhipicephalus microplus Inoculated with Metarhizium anisopliae

Dopamine (DA) is a biogenic monoamine reported to modulate insect hemocytes. Although the immune functions of DA are known in insects, there is a lack of knowledge of DA’s role in the immune system of ticks. The use of Metarhizium anisopliae has been considered for tick control, driving studies on the immune response of these arthropods challenged with fungi. The present study evaluated the effect of DA on the cellular immune response and survival of Rhipicephalus microplus inoculated with M. anisopliae blastospores. Exogenous DA increased both ticks’ survival 72 h after M. anisopliae inoculation and the number of circulating hemocytes compared to the control group, 24 h after the treatment. The phagocytic index of tick hemocytes challenged with M. anisopliae did not change upon injection of exogenous DA. Phenoloxidase activity in the hemolymph of ticks injected with DA and the fungus or exclusively with DA was higher than in untreated ticks or ticks inoculated with the fungus alone, 72 h after treatment. DA was detected in the hemocytes of fungus-treated and untreated ticks. Unveiling the cellular immune response in ticks challenged with entomopathogenic fungi is important to improve strategies for the biological control of these ectoparasites.

Effect of Bruton Tyrosine Kinase Inhibitor on Serologic and Cellular Immune Responses to Recombinant Zoster Vaccine

Introduction The recombinant zoster vaccine (RZV) is effective in preventing herpes zoster reactivation in the general population. We previously showed that patients with chronic lymphocytic leukemia (CLL), particularly those receiving Bruton tyrosine kinase inhibitors (BTKis), have decreased humoral immune responses following vaccination. The impact of vaccination on cellular immune responses in CLL patients is not well characterized. Understanding the effect of humoral and cellular immunity in CLL patients who are treatment naïve or receiving BTKis can inform vaccination strategies in this immunosuppressed patient population. Methods In this phase II open-label study (NCT03702231), patients with CLL who were either treatment naïve (TN) or receiving a BTKi (ibrutinib or acalabrutinib) received 2 doses of RZV via intramuscular injection at baseline and 3 months. Subjects were followed for 6 months and assessed for serologic response at 3 and 6 months. Serologic response was defined as a ≥ four-fold rise in anti-glycoprotein E (anti-gE) IgG serum titer at the 6 month timepoint. Cellular immune response was assessed by intracellular cytokine staining and flow cytometric analysis of gE-specific CD4+ T cells expressing upregulation of ≥2 effector molecules (interferon-γ, interleukin-2, tumor necrosis factor-α, and/or CD40 ligand). Cellular response was defined as ≥ two-fold rise over baseline and ≥320 net gE-specific CD4(2+) cells per million CD4+ T cells. Descriptive statistics were used to report vaccine response rates. Mann-Whitney test and Fisher's exact test were used to compare titers and response rates between different groups. Spearman r was used to measure the correlation between vaccine responses and clinical characteristics. All subjects completed an adverse event (AE) diary documenting any local (injection site) or systemic AE that started within 7 days after receiving the first and second vaccine dose. Results 106 subjects had serologic response assessment at 6 months. Baseline characteristics are shown in Table 1. The serologic response rate to RZV was significantly higher in the TN cohort (76.8%, 95% CI, 64.2-85.9; n = 56) compared to patients receiving a BTKi (40.0%, 95% CI,27.6-53.8; n = 50; P = .0002). Cellular vaccine response was assessed in 94 subjects at 6 months. Similarly, the rate of cellular immunity was significantly higher in the TN cohort (69.4%, 95% CI,55.5-80.5; n = 49) compared to patients treated with a BTKi (40.0%, 95% CI,27.0-54.5; n = 45, P = .0067). Paired serologic and cellular responses were available in 93 subjects. 68.5% (95% CI,55.3-79.3; n = 54) of subjects with a serologic response also had a positive cellular immune response, whereas 35.9% (95% CI,22.7-51.6; n = 39) of subjects attained a cellular immune response in absence of a serologic response (P = .0029) (Figure 1). Among subjects with a negative serologic response and a positive cellular immune response, 42.9% were TN (n = 6) and 57.1% (n = 8) received a BTKi. There was no difference in serologic or cellular responses between patients treated with ibrutinib and acalabrutinib (P &gt; 0.05). Serologic antibody titers and T cell responder frequencies were weakly positively correlated (r = 0.26; 95%CI .05-.44; P = .0127). Serologic titers and T cell responses were not correlated with age, beta-2 microglobulin, absolute lymphocyte count, absolute peripheral blood CD19+, CD3+, CD4+ or CD8+ counts or serum immunoglobulin levels (IgA, IgG, IgM) (all P &gt; 0.05). The most frequent local and systemic AEs were injection site pain (98.3%), injection site reaction (97.4%), headache (51.7%), and generalized myalgias (51.7%). Most AEs were grade 1-2 and all AEs resolved or returned to baseline within 7 days of vaccine administration. Conclusions RZV is safe in CLL patients and can induce both humoral and cellular immune responses. BTKi treatment was associated with impaired serologic and cellular vaccine responses compared to TN patients. Although BTKi therapy may inherently decrease vaccine immunogenicity, TN CLL patients could be more immunocompetent because of less advanced disease, thereby permitting more effective immune responses. The majority of patients with a positive antibody response also developed virus-specific T cells following vaccination. Approximately one third of patients without a positive serologic response developed virus reactive T cells. Figure 1 Figure 1. Disclosures Laing: Curevo Vaccine: Consultancy; MaxHealth LLC: Consultancy. Wiestner: Acerta Pharma: Research Funding; Pharmacyclics LLC: Research Funding; Merck: Research Funding; Nurix: Research Funding; Verastem: Research Funding; Genmab: Research Funding. Koelle: Merck: Research Funding; Curevo Vaccine: Other: Scientific Advisory Board ; MaxHealth LLC: Other: Scientific Advisory Board ; Oxford Immunotec: Research Funding; Sensei Biotherapeutics: Research Funding; Sanofi Pasteur: Research Funding. Sun: Genmab: Research Funding.