Age Affects Quantity but Not Quality of Antibody Responses after Vaccination with an Inactivated Flavivirus Vaccine against Tick-Borne Encephalitis

The impairment of immune functions in the elderly (immunosenescence) results in post-vaccination antibody titers that are significantly lower than in young individuals. It is, however, a controversial question whether also the quality of antibodies declines with age. In this study, we have therefore investigated the age-dependence of functional characteristics of antibody responses induced by vaccination with an inactivated flavivirus vaccine against tick-borne encephalitis (TBE). For this purpose, we quantified TBE virus-specific IgG and neutralizing antibody titers in post-vaccination sera from groups of young and elderly healthy adults and determined antibody avidities and NT/ELISA titer ratios (functional activity). In contrast to the quantitative impairment of antibody production in the elderly, we found no age-related differences in the avidity and functional activity of antibodies induced by vaccination, which also appeared to be independent of the age at primary immunization. There was no correlation between antibody avidity and NT/ELISA ratios suggesting that additional factors affect the quality of polyclonal responses, independent of age. Our work indicates that healthy elderly people are able to produce antibodies in response to vaccination with similar avidity and functional activity as young individuals, albeit at lower titers

Corrigendum: Structural Influence on the Dominance of Virus-Specific CD4 T Cell Epitopes in Zika Virus Infection

Zika virus (ZIKV) has recently caused explosive outbreaks in Pacific islands, South- and Central America. Like with other flaviviruses, protective immunity is strongly dependent on potently neutralizing antibodies (Abs) directed against the viral envelope protein E. Such Ab formation is promoted by CD4 T cells through direct interaction with B cells that present epitopes derived from E or other structural proteins of the virus. Here, we examined the extent and epitope dominance of CD4 T cell responses to capsid (C) and envelope proteins in Zika patients. All patients developed ZIKV-specific CD4 T cell responses, with substantial contributions of C and E. In both proteins, immunodominant epitopes clustered at sites that are structurally conserved among flaviviruses but have highly variable sequences, suggesting a strong impact of protein structural features on immunodominant CD4 T cell responses. Our data are particularly relevant for designing flavivirus vaccines and their evaluation in T cell assays and provide insights into the importance of viral protein structure for epitope selection and antigenicity.(VLID)470226

Neutrophils isolated from systemic lupus erythematosus patients exhibit a distinct functional phenotype

Neutrophil dysregulation, particularly of a low-density subset, is associated with systemic lupus erythematosus (SLE); however, the exact role of normal-density neutrophils in SLE remains unknown. This study compares activation and functional phenotypes of neutrophils from SLE patients and healthy controls to determine potential contributions to SLE pathogenesis. Surface activation markers and release of neutrophil extracellular traps (NETs), granule proteins, and cytokines/chemokines were measured in resting and stimulated neutrophils from SLE patients (n=19) and healthy controls (n=10). Select miRNA and mRNA involved in neutrophil development and function were also measured. Resting SLE neutrophils exhibited fewer activation markers compared to control neutrophils, and activation markers were associated with different plasma cytokines/chemokines in SLE patients compared to healthy controls. However, activation markers increased similarly in SLE and control neutrophils following stimulation with a TLR7/8 agonist, neutrophil growth factors, and bacterial mimic. At the resting state, SLE neutrophils produced significantly more CXCL10 (IP-10), with trends toward other increased cytokines/chemokines. Following stimulation, SLE neutrophils produced fewer NETs and proinflammatory cytokines compared to control neutrophils but more MMP-8. In addition, SLE neutrophils expressed less miR130a, miR132, miR27a, and miR223. In conclusion, SLE neutrophils exhibit distinct functional responses compared to control neutrophils. These functional differences may result from differential gene expression via miRNAs. Furthermore, the differences in functional phenotype of SLE neutrophils suggest that they may contribute to SLE differently dependent on the inflammatory milieu

Different Neutralization Profiles After Primary SARS-CoV-2 Omicron BA.1 and BA.2 Infections

Background and MethodsThe SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) Omicron (B.1.1.529) variant is the antigenically most distinct variant to date. As the heavily mutated spike protein enables neutralization escape, we studied serum-neutralizing activities of naïve and vaccinated individuals after Omicron BA.1 or BA.2 sub-lineage infections in live virus neutralization tests with Omicron BA.1, Omicron BA.2, wildtype (WT, B1.1), and Delta (B.1.617.2) strains. Serum samples obtained after WT infections and three-dose mRNA vaccinations with and without prior infection were included as controls.ResultsPrimary BA.1 infections yielded reduced neutralizing antibody levels against WT, Delta, and Omicron BA.2, while samples from BA.2-infected individuals showed almost no cross-neutralization against the other variants. Serum neutralization of Omicron BA.1 and BA.2 variants was detectable after three-dose mRNA vaccinations, but with reduced titers. Vaccination-breakthrough infections with either Omicron BA.1 or BA.2, however, generated equal cross-neutralizing antibody levels against all SARS-CoV-2 variants tested.ConclusionsOur study demonstrates that although Omicron variants are able to enhance cross-neutralizing antibody levels in pre-immune individuals, primary infections with BA.1 or BA.2 induced mostly variant-specific neutralizing antibodies, emphasizing the differently shaped humoral immunity induced by the two Omicron variants. These data thus contribute substantially to the understanding of antibody responses induced by primary Omicron infections or multiple exposures to different SARS-CoV-2 variants and are of particular importance for developing vaccination strategies in the light of future emerging variants

Humoral and Cellular Immune Response to RNA Immunization with Flavivirus Replicons Derived from Tick-Borne Encephalitis Virus

A new vaccination principle against flaviviruses, based on a tick-borne encephalitis virus (TBEV) self-replicating noninfectious RNA vaccine that produces subviral particles, has recently been introduced (R. M. Kofler, J. H. Aberle, S. W. Aberle, S. L. Allison, F. X. Heinz, and C. W. Mandl, Proc. Natl. Acad. Sci. USA 7:1951-1956, 2004). In this study, we evaluated the potential of the self-replicating RNA vaccine in mice in comparison to those of live, attenuated vaccines and a formalin-inactivated whole-virus vaccine (ImmunInject). For this purpose, mice were immunized using gene gun-mediated application of the RNA vaccine and tested for CD8(+) T-cell responses, long-term duration, neutralizing capacity, and isotype profile of specific antibodies and protection against lethal virus challenge. We demonstrate that the self-replicating RNA vaccine induced a broad-based, humoral and cellular (Th1 and CD8(+) T-cell response) immune response comparable to that induced by live vaccines and that it protected mice from challenge. Even a single immunization with 1 μg of the replicon induced a long-lasting antibody response, characterized by high neutralizing antibody titers, which were sustained for at least 1 year. Nevertheless, it was possible to boost this response further by a second injection with the RNA vaccine, even in the presence of a concomitant CD8(+) T-cell response. In this way it was possible to induce a balanced humoral and cellular immune response, similar to infection-induced immunity but without the safety hazards of infectious agents. The results also demonstrate the value of TBEV replicon RNA for inducing protective long-lasting antiviral responses

Effectiveness of Reverse Transcription-PCR, Virus Isolation, and Enzyme-Linked Immunosorbent Assay for Diagnosis of Influenza A Virus Infection in Different Age Groups

The degrees of effectiveness of reverse transcription (RT)-PCR, virus isolation, and antigen enzyme-linked immunosorbent assay (ELISA) for the detection of influenza A virus were evaluated with nasopharyngeal swabs from 150 patients (1 week to 86 years old) with influenza A virus infection. RT-PCR had a sensitivity for influenza A virus in stock virus preparations 10(3) times higher than virus isolation and 10(6) to 10(7) times higher than ELISA. The detection rate achieved by RT-PCR in clinical samples was clearly higher (93%) than that by virus isolation (80%) and ELISA (62%). Despite low overall detection rates achieved by antigen ELISA, samples from patients younger than 5 years old yielded higher-than-average rates in this rapid assay (88%). The likelihood of negative results in the ELISA increased significantly with increasing age of the patient (P < 0.01). The degrees of effectiveness of RT-PCR and virus isolation were not influenced by the age of the patient. Neither influenza immunizations nor the interval between onset of symptoms and laboratory investigation (mean, 4.7 days; standard deviation, 3.3 days) affected results obtained by the three test systems. Our results demonstrate that the ELISA is reliable for rapid laboratory diagnosis of influenza in infants and young children, but for older patients application of RT-PCR or virus isolation is necessary to avoid false negative results

Time-Based Prospective Memory in Schoolchildren

The present study examined age differences in time-based prospective memory (TBPM) in primary school age children and tested the role of self-initiated memory retrieval and strategic time monitoring (TM) as possible developmental mechanisms. Fifty-four children were recruited from local primary schools (27 younger children, mean age = 7.2 ± 0.55 years, and 27 older children, mean age = 9.61 ± 0.71 years). The task was a driving game scenario in which children had to drive a vehicle (ongoing task) and to remember to refuel before the vehicle runs out of gas (TBPM task, i.e., the fuel gauge served as child-appropriate time equivalent). Fuel gauge was either displayed permanently (low level of self-initiation) or could only be viewed on demand by hitting a button (high level of self-initiation). The results revealed age-dependent TBPM differences with better performance in older children. In contrast, level of self-initiated memory retrieval did not affect TBPM performance. However, strategies of TM influenced TBPM, as more frequent time checking was related to better performance. Patterns of time checking frequency differed according to children’s age and course of the game, suggesting difficulties in maintaining initial strategic TM in younger children. Taken together, the study revealed ongoing development of TBPM across primary school age. Observed age differences seemed to be associated with the ability to maintain strategic monitoring