Pauline Versteegen

Many countries continue to experience pertussis epidemics despite widespread vaccination. Waning protection after booster vaccination has highlighted the need for a better understanding of the immunological factors that promote durable protection. Here we apply systems vaccinology to investigate antibody responses in adolescents in the Netherlands (N = 14; NL) and the United Kingdom (N = 12; UK) receiving a tetanus-diphtheria-acellular pertussis-inactivated poliovirus (Tdap-IPV) vaccine. We report that early antiviral and interferon gene expression signatures in blood correlate to persistence of pertussis-specific antibody responses. Single-cell analyses of the innate response identified monocytes and myeloid dendritic cells (MoDC) as principal responders that upregulate antiviral gene expression and type-I interferon cytokine production. With public data, we show that Tdap vaccination stimulates significantly lower antiviral/type-I interferon responses than Tdap-IPV, suggesting that IPV may promote antiviral gene expression. Subsequent in vitro stimulation experiments demonstrate TLR-dependent, IPV-specific activation of the pro-inflammatory p38 MAP kinase pathway in MoDCs. Together, our data provide insights into the molecular host response to pertussis booster vaccination and demonstrate that IPV enhances innate immune activity associated with persistent, pertussis-specific antibody responses.

Bordetella pertussis(Bp), the causative agent of pertussis, continues to circulate despite widespread vaccination programs. An important question is whether and how (sub)clinical infections shape immune memory to Bp, particularly in populations primed with acellular pertussis vaccines (aP). Here, we examine the prevalence of mucosal antibodies against non-vaccine antigens in aP-primed children and adolescents of the BERT study (NCT03697798), using antibody binding to a Bp mutant strain lacking aP antigens (Bp_mut). Our study identifies increased levels of mucosal IgG and IgA binding toBp_mutin older aP-primed individuals, suggesting different Bp exposure between aP-primed birth cohorts, in line with pertussis disease incidence data. To examine whether Bp exposure influences vaccination responses, we measured mucosal antibody responses to aP booster vaccination as a secondary study outcome. Although booster vaccination induces significant increases in mucosal antibodies to Bp in both cohorts, the older age group that had higher baseline antibodies toBp_ mutshows increased persistence of antibodies after vaccination.

Booster vaccinations for pertussis are advised in many countries during childhood or adulthood. In a phase IV longitudinal interventional study, we assessed long-term immunity following an extra pertussis booster vaccination in children and adults. Children (9 years of age) were primed in infancy with either the Dutch whole cell pertussis (wP) vaccine (n = 49) or acellular pertussis (aP) vaccines (n = 59), and all children received a preschool aP booster. Adults (25–29 years, n = 86) were wP-primed in infancy and did not receive a preschool booster. All were followed-up for approximately 6 years. After the additional booster, antibody responses to pertussis were more heterogeneous but generally higher in adults compared with children, and additional modelling showed that antibody concentrations remained higher for at least a decade. Serologic parameters indicative of recent pertussis infection were more often found in aP-primed children (12%) compared with wP-primed individuals (2%) (p = 0.052). This suggests that the aP booster vaccination in aP-primed children offers less long-term protection against pertussis infection and consequently against transmission. Together, these data show that aP priming in combination with aP boosting may not be sufficient to prevent circulation and transmission, while wP-primed adults may benefit from enhanced long-lasting immunity.

Pertussis incidence has increased in many countries and the disease occurs among all age groups, suggesting the need for booster immunizations through life. In addition to determining the concentration of anti-pertussis toxin (PT) antibodies, the ability of PT neutralizing antibodies (PTNAs) could be used to assess vaccine responses. Altogether 258 participants [7–10-year-old (N = 73), 11–15-year-old (N = 85), 20–35-year-old (N = 50) and 60–70-year-old (N = 50)] were included. Sera were collected before, one month, and one year after a single dose of a three pertussis component containing acellular pertussis vaccine. The adolescents were primed in childhood either by acellular or whole-cell vaccination. PTNA titres were determined by a Chinese hamster ovary cell assay and anti-PT IgG/IgA antibody concentrations by multiplex immunoassay. In all age groups, a significant increase in levels of PTNAs and anti-PT IgG was observed one month after vaccination and remained at least two-fold higher one year post-booster, in comparison to pre-booster. Young adults had the lowest response. The strongest increase in PTNAs was observed in participants who had ≥10 IU/mL concentration of anti-PT IgG antibodies pre-booster. At pre-booster, whole-cell-primed adolescents had higher PTNAs than acellular-primed peers (p = 0.047). One year post-booster, the Finnish whole-cell-primed adolescents had a higher level of PTNAs than acellular-primed adolescents (p = 0.049), however, this was not observed in Dutch adolescents. In conclusion, PTNAs increased after vaccination in all age groups, and the strongest increase was related to the presence of high pre-booster antibodies.

Pertussis is a vaccine-preventable disease caused by the bacterium Bordetella pertussis. Over the past years, the incidence and mortality of pertussis increased significantly. A possible cause is the switch from whole-cell to acellular pertussis vaccines, although other factors may also contribute. Here, we applied high-dimensional flow cytometry to investigate changes in B cells in individuals of different ages and distinct priming backgrounds upon administration of an acellular pertussis booster vaccine. Participants were divided over four age cohorts. We compared longitudinal kinetics within each cohort and between the different cohorts. Changes in the B-cell compartment were correlated to numbers of vaccine-specific B- and plasma cells and serum Ig levels. Expansion and maturation of plasma cells 7 days postvaccination was the most prominent cellular change in all age groups and was most pronounced for more mature IgG1+ plasma cells. Plasma cell responses were stronger in individuals primed with whole-cell vaccine than in individuals primed with acellular vaccine. Moreover, IgG1+ and IgA1+ plasma cell expansion correlated with FHA-, Prn-, or PT- specific serum IgG or IgA levels. Our study indicates plasma cells as a potential early cellular marker of an immune response and contributes to understanding differences in immune responses between age groups and primary vaccination backgrounds.

To advance research and development of improved pertussis vaccines, new immunoassays are needed to qualify the outcome of Bordetella pertussis (Bp) specific CD4+ T-cell differentiation. Here, we applied a recently developed whole blood assay to evaluate Bp specific CD4+ T-cell responses. The assay is based on intracellular cytokine detection after overnight in vitro Bp antigen stimulation of diluted whole blood. We show for the first time that CD4+ T-cell memory of Th1, Th2, and Th17 lineages can be identified simultaneously in whole blood. Participants ranging from 7 to 70 years of age with different priming backgrounds of whole-cell pertussis (wP) and acellular pertussis (aP) vaccination were analyzed around an acellular booster vaccination. The assay allowed detection of low frequent antigen-specific CD4+ T-cells and revealed significantly elevated numbers of activated and cytokine-producing CD4+ T-cells, with a significant tendency to segregate recall responses based on primary vaccination background. A stronger Th2 response hallmarked an aP primed cohort compared to a wP primed cohort. In conclusion, analysis of Bp specific CD4+ T-cell responses in whole blood showed separation based on vaccination background and provides a promising tool to assess the quantity and quality of CD4+ T-cell responses induced by vaccine candidates.

Background: Pertussis can lead to serious disease and even death in infants. In addition older adults and patients with chronic diseases are more vulnerable to complications. In high-income countries, priming vaccination in infancy is usually undertaken using acellular pertussis vaccines. There is a significant between-country variation in the use of booster vaccinations which are administered at different ages and to different target populations. We investigated the effect of age on the response to acellular pertussis booster vaccination in three European countries. Methods: In total 379 participants, divided between four age groups - children (7-10y), adolescents (11-15y), young adults (20-34y), and older adults (60-70y) - received a pertussis toxoid, filamentous haemagglutinin, and pertactin containing booster vaccine. Serum IgG and IgA antibody concentrations to pertussis vaccine antigens at day 0, day 28, and one year were measured with a multiplex immunoassay. Findings: Participants from all four age groups showed high IgG antibodies to pertussis toxin at day 28. IgG antibody concentrations at 28 days and one year postvaccination were comparable between the age groups, but IgA concentrations showed an increase of antibody concentrations with age at all timepoints. Interpretation: Acellular pertussis booster vaccination induces comparable serological responses in older adults as younger age groups and could be considered for older adults in order to increase their protection. Trial Registration: The trial was registered at the EU Clinical Trial database (EudraCT number 2016-003678-42). Funding: PERISCOPE has received funding from the Innovative Medicines Initiative2 Joint Undertaking under grant agreement No 115910. This Joint Undertaking receives support from the European Union’s Horizon 2020 research and innovation programme, EFPIA and BMGF. Declaration of Interests: None of the authors received payment or service from a third part at any time, nor does anyone have a financial relationship with entities in the bio-medical arena. None of the authors have any patents relevant to the work. MVP is a member of the Portuguese National Immunisation Technical Advisory Group (Comissão Técnica de Vacinação da Direcção Geral de Saúde). Ethics Approval Statement: The trial was approved by the Medical Research Ethics Committees United (MEC-U, NL60807.100.17-R17.039) in the Netherlands, the South Central - Hampshire B Research Ethics Committee (REC, 19/SC/0368) in the UK, and the MREC UTU (ETMK Dnro: 129/1800/2017) in Finland. Written informed consent was obtained from all adult participants, and parents or legal guardian of minors, at the start of the study.

Tuberculous meningitis (TBM), the most severe extrapulmonary manifestation of tuberculosis, is caused by the pathogen Mycobacterium tuberculosis . The M. tuberculosis complex includes seven lineages, all described to harbor a unique geographical dissemination pattern and clinical presentation. In this study, we set out to determine whether a certain M. tuberculosis lineage demonstrated tropism to cause TBM in patients from Cape Town, South Africa.