Intravital imaging of the human cornea reveals the differential effects of season on innate and adaptive immune cell morphodynamics.

PURPOSE: While the external environment has been shown to shape the systemic human immune landscape, defining the in vivo immune status of peripheral tissues has remained a technical challenge. We recently developed functional in vivo confocal microscopy (Fun-IVCM) for dynamic, longitudinal imaging of corneal immune cells in living humans. This study investigated the effect of seasonal-driven environmental factors on the density, morphology and dynamic behavior of human corneal immune cell subsets. DESIGN: Longitudinal, observational clinical study. PARTICIPANTS: Sixteen healthy participants (18-40 years) attended two visits in distinct seasons in Melbourne, Australia (Visit 1: Spring/Summer: November-December 2021; Visit 2: Autumn/Winter: April-June 2022). METHODS: Environmental data were collected over each period. Participants underwent ocular surface examinations and corneal Fun-IVCM (Heidelberg HRT-3, Rostock Corneal Module). Volume scans (80µm) were acquired at 5.5±1.5 minute intervals, for up to five timepoints. Time-lapse videos were created to analyze corneal immune cells, comprising epithelial T cells and dendritic cells (DCs), and stromal macrophages. Tear cytokines were analyzed using multiplex bead-based immunoassay. MAIN OUTCOME MEASURES: Difference in the density, morphological and dynamic parameters of corneal immune cell subsets over the study periods. RESULTS: Visit 1 was characterized by higher temperature, lower humidity, and higher air particulate and pollen levels than Visit 2. Clinical ocular surface parameters, and the density of immune cell subsets were similar across visits. At Visit 1 (Spring/Summer), corneal epithelial DCs were larger and more elongated, with a lower dendrite probing speed (0.38±0.21 vs 0.68±0.33µm/min, p<0.001) relative to Visit 2; stromal macrophages were more circular and had less dynamic activity (Visit 1: 7.2±1.9 vs Visit 2: 10.3±3.7 'dancing index', p<0.001). T cell morphology and dynamics were unchanged across periods. Basal tear levels of IL-2 and CXCL10 were lower during Spring/Summer. CONCLUSION: This novel study shows that the in vivo morphodynamics of innate corneal immune cells (DCs, macrophages) are modified by environmental factors, but such effects are not evident for adaptive immune cells (T cells). The cornea is a potential non-invasive, in vivo 'window' to season-dependent changes to the human immune system, with capacity to yield new insight into environmental influences on immune regulation.

Influenza antibody breadth and effector functions are immune correlates from acquisition of pandemic infection of children.

Cross-reactive antibodies with Fc receptor (FcR) effector functions may mitigate pandemic virus impact in the absence of neutralizing antibodies. In this exploratory study, we use serum from a randomized placebo-controlled trial of seasonal trivalent influenza vaccination in children (NCT00792051) conducted at the onset of the 2009 H1N1 pandemic (pH1N1) and monitored for infection. We found that seasonal vaccination increases pH1N1 specific antibodies and FcR effector functions. Furthermore, prospective baseline antibody profiles after seasonal vaccination, prior to pH1N1 infection, show that unvaccinated uninfected children have elevated ADCC effector function, FcγR3a and FcγR2a binding antibodies to multiple pH1N1 proteins, past seasonal and avian (H5, H7 and H9) strains. Whereas, children that became pH1N1 infected after seasonal vaccination have antibodies focussed to seasonal strains without FcR functions, and greater aggregated HA-specific profiles for IgM and IgG3. Modeling to predict infection susceptibility, ranked baseline hemagglutination antibody inhibition as the highest contributor to lack of pH1N1 infection, in combination with features that include pH1-IgG1, H1-stem responses and FcR binding to seasonal vaccine and pH1 proteins. Thus, seasonal vaccination can have benefits against pandemic influenza viruses, and some children already have broadly reactive antibodies with Fc potential without vaccination and may be considered 'elite influenza controllers'.

Immunoglobulin G genetic variation can confound assessment of antibody levels via altered binding to detection reagents.

Objectives: Amino acid variations across more than 30 immunoglobulin (Ig) allotypes may introduce structural changes that influence recognition by anti-Ig detection reagents, consequently confounding interpretation of antibody responses, particularly in genetically diverse cohorts. Here, we assessed a panel of commercial monoclonal anti-IgG1 clones for capacity to universally recognise two dominant IgG1 haplotypes (G1m-1,3 and G1m1,17). Methods: Four commercial monoclonal anti-human IgG1 clones were assessed via ELISAs and multiplex bead-based assays for their ability to bind G1m-1,3 and G1m1,17 IgG1 variants. Detection antibodies were validated against monoclonal IgG1 allotype standards and tested for capacity to recognise antigen-specific plasma IgG1 from G1m-1,3 and G1m1,17 homozygous and heterozygous SARS-CoV-2 BNT162b2 vaccinated (n = 28) and COVID-19 convalescent (n = 44) individuals. An Fc-specific pan-IgG detection antibody corroborated differences between hinge- and Fc-specific anti-IgG1 responses. Results: Hinge-specific anti-IgG1 clone 4E3 preferentially bound G1m1,17 compared to G1m-1,3 IgG1. Consequently, SARS-CoV-2 Spike-specific IgG1 levels detected in G1m1,17/G1m1,17 BNT162b2 vaccinees appeared 9- to 17-fold higher than in G1m-1,3/G1m-1,3 vaccinees. Fc-specific IgG1 and pan-IgG detection antibodies equivalently bound G1m-1,3 and G1m1,17 IgG1 variants, and detected comparable Spike-specific IgG1 levels between haplotypes. IgG1 responses against other human coronaviruses and influenza were similarly poorly detected by 4E3 anti-IgG1 in G1m-1,3/G1m-1,3 subjects. Conclusion: Anti-IgG1 clone 4E3 confounds assessment of antibody responses in clinical cohorts owing to bias towards detection of G1m1,17 IgG1 variants. Validation of anti-Ig clones should include evaluation of binding to relevant antibody variants, particularly as the role of immunogenetics upon humoral immunity is increasingly explored in diverse populations.

Altered IgG4 Antibody Response to Repeated mRNA versus Protein COVID Vaccines.

Repeated mRNA SARS-CoV-2 vaccination has been associated with increases in the proportion of IgG4 in spike-specific antibody responses and concurrent reductions in Fcγ-mediated effector functions that may limit control of viral infection. Here, we assessed anti-Spike total IgG, IgG1, IgG2, IgG3 and IgG4, and surrogate markers for antibody-dependent cellular phagocytosis (ADCP, FcγRIIa binding), antibody-dependent cellular cytotoxicity (ADCC, FcγRIIIa binding), and antibody-dependent complement deposition (ADCD, C1q binding) associated with repeated SARS-CoV-2 vaccination with NVX-CoV2373 (Novavax Inc., Gaithersburg, MD). The NVX-CoV2373 protein vaccine did not induce notable increases in spike-specific IgG4 or negatively impact surrogates for Fcγ effector responses. Conversely, repeated NVX-CoV2373 vaccination uniquely enhanced IgG3 responses which are known to exhibit strong affinity for FcγRIIIa and have previously been linked to potent neutralization of SARS-CoV-2. Subsequent investigations will help to understand the immunological diversity generated by different SARS-CoV-2 vaccine types and have the potential to reshape public health strategies.

Antibody glycosylation correlates with disease progression in SIV-Mycobacterium tuberculosis coinfected cynomolgus macaques.

Objectives: Tuberculosis (TB) remains a substantial cause of morbidity and mortality among people living with human immunodeficiency virus (HIV) worldwide. However, the immunological mechanisms associated with the enhanced susceptibility among HIV-positive individuals remain largely unknown. Methods: Here, we used a simian immunodeficiency virus (SIV)/TB-coinfection Mauritian cynomolgus macaque (MCM) model to examine humoral responses from the plasma of SIV-negative (n = 8) and SIV-positive (n = 7) MCM 8-week postinfection with Mycobacterium tuberculosis (Mtb). Results: Antibody responses to Mtb were impaired during SIV coinfection. Elevated inflammatory bulk IgG antibody glycosylation patterns were observed in coinfected macaques early at 8-week post-Mtb infection, including increased agalactosylation (G0) and reduced di-galactosylation (G2), which correlated with endpoint Mtb bacterial burden and gross pathology scores, as well as the time-to-necropsy. Conclusion: These studies suggest that humoral immunity may contribute to control of TB disease and support growing literature that highlights antibody Fc glycosylation as a biomarker of TB disease progression.

Interim results from a phase I randomized, placebo-controlled trial of novel SARS-CoV-2 beta variant receptor-binding domain recombinant protein and mRNA vaccines as a 4th dose booster.

BACKGROUND: SARS-CoV-2 booster vaccination should ideally enhance protection against variants and minimise immune imprinting. This Phase I trial evaluated two vaccines targeting SARS-CoV-2 beta-variant receptor-binding domain (RBD): a recombinant dimeric RBD-human IgG1 Fc-fusion protein, and an mRNA encoding a membrane-anchored RBD. METHODS: 76 healthy adults aged 18-64 y, previously triple vaccinated with licensed SARS-CoV-2 vaccines, were randomised to receive a 4th dose of either an adjuvanted (MF59®, CSL Seqirus) protein vaccine (5, 15 or 45 µg, N = 32), mRNA vaccine (10, 20, or 50 µg, N = 32), or placebo (saline, N = 12) at least 90 days after a 3rd boost vaccination or SARS-CoV-2 infection. Bleeds occurred on days 1 (prior to vaccination), 8, and 29. CLINICALTRIALS: govNCT05272605. FINDINGS: No vaccine-related serious or medically-attended adverse events occurred. The protein vaccine reactogenicity was mild, whereas the mRNA vaccine was moderately reactogenic at higher dose levels. Best anti-RBD antibody responses resulted from the higher doses of each vaccine. A similar pattern was seen with live virus neutralisation and surrogate, and pseudovirus neutralisation assays. Breadth of immune response was demonstrated against BA.5 and more recent omicron subvariants (XBB, XBB.1.5 and BQ.1.1). Binding antibody titres for both vaccines were comparable to those of a licensed bivalent mRNA vaccine. Both vaccines enhanced CD4+ and CD8+ T cell activation. INTERPRETATION: There were no safety concerns and the reactogenicity profile was mild and similar to licensed SARS-CoV-2 vaccines. Both vaccines showed strong immune boosting against beta, ancestral and omicron strains. FUNDING: Australian Government Medical Research Future Fund, and philanthropies Jack Ma Foundation and IFM investors.

Preexisting immunity restricts mucosal antibody recognition of SARS-CoV-2 and Fc profiles during breakthrough infections.

Understanding mucosal antibody responses from SARS-CoV-2 infection and/or vaccination is crucial to develop strategies for longer term immunity, especially against emerging viral variants. We profiled serial paired mucosal and plasma antibodies from COVID-19 vaccinated only vaccinees (vaccinated, uninfected), COVID-19-recovered vaccinees (recovered, vaccinated), and individuals with breakthrough Delta or Omicron BA.2 infections (vaccinated, infected). Saliva from COVID-19-recovered vaccinees displayed improved antibody-neutralizing activity, Fcγ receptor (FcγR) engagement, and IgA levels compared with COVID-19-uninfected vaccinees. Furthermore, repeated mRNA vaccination boosted SARS-CoV-2-specific IgG2 and IgG4 responses in both mucosa biofluids (saliva and tears) and plasma; however, these rises only negatively correlated with FcγR engagement in plasma. IgG and FcγR engagement, but not IgA, responses to breakthrough COVID-19 variants were dampened and narrowed by increased preexisting vaccine-induced immunity against the ancestral strain. Salivary antibodies delayed initiation following breakthrough COVID-19 infection, especially Omicron BA.2, but rose rapidly thereafter. Importantly, salivary antibody FcγR engagements were enhanced following breakthrough infections. Our data highlight how preexisting immunity shapes mucosal SARS-CoV-2-specific antibody responses and has implications for long-term protection from COVID-19.

Mucosal antibody responses following Vaxzevria vaccination.

Mucosal antibodies play a key role in protection against breakthrough COVID-19 infections and emerging viral variants. Intramuscular adenovirus-based vaccination (Vaxzevria) only weakly induces nasal IgG and IgA responses, unless vaccinees have been previously infected. However, little is known about how Vaxzevria vaccination impacts the ability of mucosal antibodies to induce Fc responses, particularly against SARS-CoV-2 variants of concern (VoCs). Here, we profiled paired mucosal (saliva, tears) and plasma antibodies from COVID-19 vaccinated only vaccinees (uninfected, vaccinated) and COVID-19 recovered vaccinees (COVID-19 recovered, vaccinated) who both received Vaxzevria vaccines. SARS-CoV-2 ancestral-specific IgG antibodies capable of engaging FcγR3a were significantly higher in the mucosal samples of COVID-19 recovered Vaxzevria vaccinees in comparison with vaccinated only vaccinees. However, when IgG and FcγR3a engaging antibodies were tested against a panel of SARS-CoV-2 VoCs, the responses were ancestral-centric with weaker recognition of Omicron strains observed. In contrast, salivary IgA, but not plasma IgA, from Vaxzevria vaccinees displayed broad cross-reactivity across all SARS-CoV-2 VoCs tested. Our data highlight that while intramuscular Vaxzevria vaccination can enhance mucosal antibodies responses in COVID-19 recovered vaccinees, restrictions by ancestral-centric bias may have implications for COVID-19 protection. However, highly cross-reactive mucosal IgA could be key in addressing these gaps in mucosal immunity and may be an important focus of future SARS-CoV-2 vaccine development.

Polyfunctional antibodies: a path towards precision vaccines for vulnerable populations.

Vaccine efficacy determined within the controlled environment of a clinical trial is usually substantially greater than real-world vaccine effectiveness. Typically, this results from reduced protection of immunologically vulnerable populations, such as children, elderly individuals and people with chronic comorbidities. Consequently, these high-risk groups are frequently recommended tailored immunisation schedules to boost responses. In addition, diverse groups of healthy adults may also be variably protected by the same vaccine regimen. Current population-based vaccination strategies that consider basic clinical parameters offer a glimpse into what may be achievable if more nuanced aspects of the immune response are considered in vaccine design. To date, vaccine development has been largely empirical. However, next-generation approaches require more rational strategies. We foresee a generation of precision vaccines that consider the mechanistic basis of vaccine response variations associated with both immunogenetic and baseline health differences. Recent efforts have highlighted the importance of balanced and diverse extra-neutralising antibody functions for vaccine-induced protection. However, in immunologically vulnerable populations, significant modulation of polyfunctional antibody responses that mediate both neutralisation and effector functions has been observed. Here, we review the current understanding of key genetic and inflammatory modulators of antibody polyfunctionality that affect vaccination outcomes and consider how this knowledge may be harnessed to tailor vaccine design for improved public health.

Potent pan huACE2-dependent sarbecovirus neutralizing monoclonal antibodies isolated from a BNT162b2-vaccinated SARS survivor.

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern such as Omicron hampered efforts in controlling the ongoing coronavirus disease 2019 pandemic due to their ability to escape neutralizing antibodies induced by vaccination or prior infection, highlighting the need to develop broad-spectrum vaccines and therapeutics. Most human monoclonal antibodies (mAbs) reported to date have not demonstrated true pan-sarbecovirus neutralizing breadth especially against animal sarbecoviruses. Here, we report the isolation and characterization of highly potent mAbs targeting the receptor binding domain (RBD) of huACE2-dependent sarbecovirus from a SARS-CoV survivor vaccinated with BNT162b2. Among the six mAbs identified, one (E7) showed better huACE2-dependent sarbecovirus neutralizing potency and breadth than any other mAbs reported to date. Mutagenesis and cryo-electron microscopy studies indicate that these mAbs have a unique RBD contact footprint and that E7 binds to a quaternary structure-dependent epitope.

Antibody Fc-binding profiles and ACE2 affinity to SARS-CoV-2 RBD variants.

Emerging SARS-CoV-2 variants, notably Omicron, continue to remain a formidable challenge to worldwide public health. The SARS-CoV-2 receptor-binding domain (RBD) is a hotspot for mutations, reflecting its critical role at the ACE2 interface during viral entry. Here, we comprehensively investigated the impact of RBD mutations, including 5 variants of concern (VOC) or interest-including Omicron (BA.2)-and 33 common point mutations, both on IgG recognition and ACE2-binding inhibition, as well as FcγRIIa- and FcγRIIIa-binding antibodies, in plasma from two-dose BNT162b2-vaccine recipients and mild-COVID-19 convalescent subjects obtained during the first wave using a custom-designed bead-based 39-plex array. IgG-recognition and FcγR-binding antibodies were decreased against the RBD of Beta and Omicron, as well as point mutation G446S, found in several Omicron sub-variants as compared to wild type. Notably, while there was a profound decrease in ACE2 inhibition against Omicron, FcγR-binding antibodies were less affected, suggesting that Fc functional antibody responses may be better retained against the RBD of Omicron in comparison to neutralization. Furthermore, while measurement of RBD-ACE2-binding affinity via biolayer interferometry showed that all VOC RBDs have enhanced affinity to human ACE2, we demonstrate that human ACE2 polymorphisms, E35K (rs1348114695) has reduced affinity to VOCs, while K26R (rs4646116) and S19P (rs73635825) have increased binding kinetics to the RBD of VOCs, potentially affecting virus-host interaction and, thereby, host susceptibility. Collectively, our findings provide in-depth coverage of the impact of RBD mutations on key facets of host-virus interactions.

Adenovirus vector produced Zika virus-like particles induce a long-lived neutralising antibody response in mice.

Countermeasures against Zika virus (ZIKV) epidemics are urgently needed. In this study we generated a ZIKV virus-like particle (VLP) based vaccine candidate and assessed the immunogenicity of these particles in mice. The ZIKV-VLPs were morphologically similar to ZIKV by electron microscopy and were recognized by anti-Flavivirus neutralising antibodies. We observed that a single dose of unadjuvanted ZIKV-VLPs, or inactivated ZIKV, generated an immune response that lasted over 6 months, but did not neutralize ZIKV infection of cells in vitro. However, when we co-administered the ZIKV VLPs with either Aluminium hydroxide (Alhydrogel®; Alum), AddaVax or Pam2Cys we observed that Alum was the most effective in a single dose regime, since it not only produced antibodies that neutralized the virus, but also generated a greater number of antigen-specific memory B cells. We additionally observed that the generation of the neutralising antibodies persisted for up to 6 months. Our results suggest that a single dose ZIKV VLPs could be a suitable single dose vaccine candidate for use in outbreak settings.

Robust immunity to influenza vaccination in haematopoietic stem cell transplant recipients following reconstitution of humoral and adaptive immunity.

Objectives: Influenza causes significant morbidity and mortality, especially in high-risk populations. Although current vaccination regimens are the best method to combat annual influenza disease, vaccine efficacy can be low in high-risk groups, such as haematopoietic stem cell transplant (HSCT) recipients. Methods: We comprehensively assessed humoral immunity, antibody landscapes, systems serology and influenza-specific B-cell responses, together with their phenotypes and isotypes, to the inactivated influenza vaccine (IIV) in HSCT recipients in comparison to healthy controls. Results: Inactivated influenza vaccine significantly increased haemagglutination inhibition (HAI) titres in HSCT recipients, similar to healthy controls. Systems serology revealed increased IgG1 and IgG3 antibody levels towards the haemagglutinin (HA) head, but not to neuraminidase, nucleoprotein or HA stem. IIV also increased frequencies of total, IgG class-switched and CD21loCD27+ influenza-specific B cells, determined by HA probes and flow cytometry. Strikingly, 40% of HSCT recipients had markedly higher antibody responses towards A/H3N2 vaccine strain than healthy controls and showed cross-reactivity to antigenically drifted A/H3N2 strains by antibody landscape analysis. These superior humoral responses were associated with a greater time interval after HSCT, while multivariant analyses revealed the importance of pre-existing immune memory. Conversely, in HSCT recipients who did not respond to the first dose, the second IIV dose did not greatly improve their humoral response, although 50% of second-dose patients reached a seroprotective HAI titre for at least one of vaccine strains. Conclusions: Our study demonstrates efficient, although time-dependent, immune responses to IIV in HSCT recipients, and provides insights into influenza vaccination strategies targeted to immunocompromised high-risk groups.

Broad immunity to SARS-CoV-2 variants of concern mediated by a SARS-CoV-2 receptor-binding domain protein vaccine.

BACKGROUND: The SARS-CoV-2 global pandemic has fuelled the generation of vaccines at an unprecedented pace and scale. However, many challenges remain, including: the emergence of vaccine-resistant mutant viruses, vaccine stability during storage and transport, waning vaccine-induced immunity, and concerns about infrequent adverse events associated with existing vaccines. METHODS: We report on a protein subunit vaccine comprising the receptor-binding domain (RBD) of the ancestral SARS-CoV-2 spike protein, dimerised with an immunoglobulin IgG1 Fc domain. These were tested in conjunction with three different adjuvants: a TLR2 agonist R4-Pam2Cys, an NKT cell agonist glycolipid α-Galactosylceramide, or MF59® squalene oil-in-water adjuvant, using mice, rats and hamsters. We also developed an RBD-human IgG1 Fc vaccine with an RBD sequence of the immuno-evasive beta variant (N501Y, E484K, K417N). These vaccines were also tested as a heterologous third dose booster in mice, following priming with whole spike vaccine. FINDINGS: Each formulation of the RBD-Fc vaccines drove strong neutralising antibody (nAb) responses and provided durable and highly protective immunity against lower and upper airway infection in mouse models of COVID-19. The 'beta variant' RBD vaccine, combined with MF59® adjuvant, induced strong protection in mice against the beta strain as well as the ancestral strain. Furthermore, when used as a heterologous third dose booster, the RBD-Fc vaccines combined with MF59® increased titres of nAb against other variants including alpha, delta, delta+, gamma, lambda, mu, and omicron BA.1, BA.2 and BA.5. INTERPRETATION: These results demonstrated that an RBD-Fc protein subunit/MF59® adjuvanted vaccine can induce high levels of broadly reactive nAbs, including when used as a booster following prior immunisation of mice with whole ancestral-strain spike vaccines. This vaccine platform offers a potential approach to augment some of the currently approved vaccines in the face of emerging variants of concern, and it has now entered a phase I clinical trial. FUNDING: This work was supported by grants from the Medical Research Future Fund (MRFF) (2005846), The Jack Ma Foundation, National Health and Medical Research Council of Australia (NHMRC; 1113293) and Singapore National Medical Research Council (MOH-COVID19RF-003). Individual researchers were supported by an NHMRC Senior Principal Research Fellowship (1117766), NHMRC Investigator Awards (2008913 and 1173871), Australian Research Council Discovery Early Career Research Award (ARC DECRA; DE210100705) and philanthropic awards from IFM investors and the A2 Milk Company.

Robust and prototypical immune responses toward COVID-19 vaccine in First Nations peoples are impacted by comorbidities.

High-risk groups, including Indigenous people, are at risk of severe COVID-19. Here we found that Australian First Nations peoples elicit effective immune responses to COVID-19 BNT162b2 vaccination, including neutralizing antibodies, receptor-binding domain (RBD) antibodies, SARS-CoV-2 spike-specific B cells, and CD4+ and CD8+ T cells. In First Nations participants, RBD IgG antibody titers were correlated with body mass index and negatively correlated with age. Reduced RBD antibodies, spike-specific B cells and follicular helper T cells were found in vaccinated participants with chronic conditions (diabetes, renal disease) and were strongly associated with altered glycosylation of IgG and increased interleukin-18 levels in the plasma. These immune perturbations were also found in non-Indigenous people with comorbidities, indicating that they were related to comorbidities rather than ethnicity. However, our study is of a great importance to First Nations peoples who have disproportionate rates of chronic comorbidities and provides evidence of robust immune responses after COVID-19 vaccination in Indigenous people.

Immune profiling of SARS-CoV-2 infection during pregnancy reveals NK cell and γδ T cell perturbations.

Pregnancy poses a greater risk for severe COVID-19; however, underlying immunological changes associated with SARS-CoV-2 during pregnancy are poorly understood. We defined immune responses to SARS-CoV-2 in unvaccinated pregnant and nonpregnant women with acute and convalescent COVID-19, quantifying 217 immunological parameters. Humoral responses to SARS-CoV-2 were similar in pregnant and nonpregnant women, although our systems serology approach revealed distinct antibody and FcγR profiles between pregnant and nonpregnant women. Cellular analyses demonstrated marked differences in NK cell and unconventional T cell activation dynamics in pregnant women. Healthy pregnant women displayed preactivated NK cells and γδ T cells when compared with healthy nonpregnant women, which remained unchanged during acute and convalescent COVID-19. Conversely, nonpregnant women had prototypical activation of NK and γδ T cells. Activation of CD4+ and CD8+ T cells and T follicular helper cells was similar in SARS-CoV-2-infected pregnant and nonpregnant women, while antibody-secreting B cells were increased in pregnant women during acute COVID-19. Elevated levels of IL-8, IL-10, and IL-18 were found in pregnant women in their healthy state, and these cytokine levels remained elevated during acute and convalescent COVID-19. Collectively, we demonstrate perturbations in NK cell and γδ T cell activation in unvaccinated pregnant women with COVID-19, which may impact disease progression and severity during pregnancy.

Predictors of Post-Traumatic Growth in a Sample of United Kingdom Mental and Community Healthcare Workers during the COVID-19 Pandemic.

Experiences of adversity can generate positive psychological effects alongside negative impacts. Little research to date has evaluated predictors of post-traumatic growth in mental or community healthcare workers during the COVID-19 pandemic. Following a survey of 854 community and mental healthcare staff in the United Kingdom in July to September 2020, multiple linear regression was used to determine the association between hypothesised risk and protective factors (personal, organisational and environmental variables) and total scores on the Post-traumatic Growth Inventory-Short Version. Positive self-reflection activities, black and minority ethnic status, developing new healthcare knowledge and skills, connecting with friends and family, feeling supported by senior management, feeling supported by the UK people, and anxiety about the personal and work-related consequences of COVID-19 each significantly independently predicted greater post-traumatic growth. Working in a clinical role and in mental healthcare or community physical healthcare predicted lower post-traumatic growth. Our research supports the value of taking an organisational growth-focused approach to occupational health during times of adversity, by supporting staff to embrace opportunities for personal growth. Valuing staff's cultural and religious identity and encouraging self-reflective activities, such as mindfulness and meditation, may help to promote post-traumatic growth.

Acquisition of antibodies to Plasmodium falciparum and Plasmodium vivax antigens in pregnant women living in a low malaria transmission area of Brazil.

BACKGROUND: Pregnant women have increased susceptibility to Plasmodium falciparum malaria and acquire protective antibodies over successive pregnancies. Most studies that investigated malaria antibody responses in pregnant women are from high transmission areas in sub-Saharan Africa, while reports from Latin America are scarce and inconsistent. The present study sought to explore the development of antibodies against P. falciparum and Plasmodium vivax antigens in pregnant women living in a low transmission area in the Brazilian Amazon. METHODS: In a prospective cohort study, plasma samples from 408 pregnant women (of whom 111 were infected with P. falciparum, 96 had infections with P. falciparum and P. vivax, and 201 had no Plasmodium infection) were used to measure antibody levels. Levels of IgG and opsonizing antibody to pregnancy-specific variant surface antigens (VSAs) on infected erythrocytes (IEs), 10 recombinant VAR2CSA Duffy binding like (DBL domains), 10 non-pregnancy-specific P. falciparum merozoite antigens, and 10 P. vivax antigens were measured by flow cytometry, ELISA, and multiplex assays. Antibody levels and seropositivity among the groups were compared. RESULTS: Antibodies to VSAs on P. falciparum IEs were generally low but were higher in currently infected women and women with multiple P. falciparum episodes over pregnancy. Many women (21%-69%) had antibodies against each individual VAR2CSA DBL domain, and antibodies to DBLs correlated with each other (r ≥ 0.55, p < 0.0001), but not with antibody to VSA or history of infection. Infection with either malaria species was associated with higher seropositivity rate for antibodies against P. vivax proteins, adjusted odds ratios (95% CI) ranged from 5.6 (3.2, 9.7), p < 0.0001 for PVDBPII-Sal1 to 15.7 (8.3, 29.7), p < 0.0001 for PvTRAg_2. CONCLUSIONS: Pregnant Brazilian women had low levels of antibodies to pregnancy-specific VSAs that increased with exposure. They frequently recognized both VAR2CSA DBL domains and P. vivax antigens, but only the latter varied with infection. Apparent antibody prevalence is highly dependent on the assay platform used.

Heterologous SARS-CoV-2 IgA neutralising antibody responses in convalescent plasma.

Objectives: Following infection with SARS-CoV-2, virus-specific antibodies are generated, which can both neutralise virions and clear infection via Fc effector functions. The importance of IgG antibodies for protection and control of SARS-CoV-2 has been extensively reported. By comparison, other antibody isotypes including IgA have been poorly characterised. Methods: Here, we characterised plasma IgA from 41 early convalescent COVID-19 subjects for neutralisation and Fc effector functions. Results: Convalescent plasma IgA from > 60% of the cohort had the capacity to inhibit the interaction between wild-type RBD and ACE2. Furthermore, a third of the cohort induced stronger IgA-mediated ACE2 inhibition than matched IgG when tested at equivalent concentrations. Plasma IgA and IgG from this cohort broadly recognised similar RBD epitopes and had similar capacities to inhibit ACE2 from binding to 22 of the 23 prevalent RBD mutations assessed. However, plasma IgA was largely incapable of mediating antibody-dependent phagocytosis in comparison with plasma IgG. Conclusion: Overall, convalescent plasma IgA contributed to the neutralising antibody response of wild-type SARS-CoV-2 RBD and various RBD mutations. However, this response displayed large heterogeneity and was less potent than IgG.