Enhancing livestock biosecurity is critical to safeguard the livelihoods of farmers, global and local economies, and food security. Vaccination is fundamental to the control and prevention of exotic and endemic high-priority infectious livestock diseases. Successful implementation of vaccination in a biosecurity plan is underpinned by a strong understanding of correlates of protection—those elements of the immune response that can reliably predict the level of protection from viral challenge. While correlates of protection have been successfully characterized for many human viral vaccines, for many high-priority livestock viral diseases, including African swine fever and foot and mouth disease, they remain largely uncharacterized. Current literature provides insights into potential correlates of protection that should be assessed during vaccine development for these high-priority mammalian livestock viral diseases. Establishment of correlates of protection for biosecurity purposes enables immune surveillance, rationale for vaccine development, and successful implementation of livestock vaccines as part of a biosecurity strategy.

Linear immunoglobulin A (IgA) bullous dermatosis (LABD) is an autoimmune disease affecting children or adults that leads to subepithelial vesiculobullous lesions on the skin and/or mucosa. Due to the histologic and clinical appearance of the disease with tense and pruritic blisters, direct immunofluorescence is required for diagnosis, which features the characteristic linear deposition of IgA autoantibodies along the basement membrane zone. LABD can be idiopathic, drug-induced, or associated with a systemic disease such as inflammatory bowel disease. Many drugs have been implicated, such as antibiotics, anti-hypertensives, anti-epileptics, analgesics, and immunosuppressive medications. Treatment of LABD centers on discontinuation of the offending drug, if applicable, as well as pharmacotherapy with dapsone as the first-line treatment. Adjunctive therapy with sulphonamides, systemic corticosteroids, cyclosporine, colchicine, intravenous immunoglobulins, tetracyclines, erythromycin, and dicloxacillin has also shown benefits. We report the case of a young adult patient who developed LABD with a background of recent initiation of treatment with imipramine and newly diagnosed ulcerative colitis.

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.

SummaryUnderstanding 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 (convalescent, vaccinated) and individuals with breakthrough Delta or Omicron BA.2 infections (vaccinated, infected). Saliva from COVID-19 recovered vaccinees displayed improved antibody neutralizing activity, FcγR engagement and IgA compared to 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. IgG, but not IgA, responses to breakthrough COVID-19 variants were dampened and narrowed by increased pre-existing vaccine-induced immunity to the ancestral strain. Salivary antibodies delayed initiation of boosting following breakthrough COVID-19 infection, especially Omicron BA.2, however, rose rapidly thereafter. Our data highlight how pre-existing immunity shapes mucosal SARS-CoV-2-specific antibody responses and has implications for long-term protection from COVID-19.

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.

Translation: The University of Toledo Journal of Medical Sciences is the online journal launched by the University of Toledo. Manuscripts will be considered on the understanding that they report original work and are not under consideration for publication by any other journal. The journal publishes original articles reporting experimental results of basic or clinical research, case reports, and reviews. The journal uses a single blind peer review system and each manuscript, based on the results presented in its original submission, will be evaluated by two student reviewers and one faculty reviewer. This process will provide an opportunity for medical students, graduate students, residents, fellows and faculty to publish research observation in a timely manner.

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.

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants remains a formidable challenge to worldwide public health. The receptor binding domain (RBD) of the SARS-CoV-2 spike protein is a hotspot for mutations, reflecting its critical role at the ACE2 interface during viral entry. We comprehensively investigated the impact of RBD mutations, including 6 variants of concern (VOC) or interest (Alpha, Beta, Gamma, Delta, Kappa and Omicron) and 33 common point mutations, on IgG recognition, FcγR-engagement, and ACE2-binding inhibition in plasma from BNT162b2-vaccine recipients (two-weeks following second dose) and mild-to-moderate COVID-19 convalescent subjects using our custom bead-based 39-plex array. We observed that IgG-recognition and FcγR-binding antibodies were most profoundly decreased against Beta and Omicron RBDs, as well as point mutations G446S, found in Omicron, and N501T, a key mutation found in animal adapted SARS-CoV-2 viruses. Measurement of RBD-ACE2 binding affinity via Biolayer Interferometry showed all VOC RBDs have enhanced affinity to human ACE2. Furthermore we demonstrate that human ACE2 polymorphisms, E35K (rs1348114695), K26R (rs4646116) and S19P (rs73635825), have altered binding kinetics to the RBD of VOCs potentially affecting virus-host interaction and thereby host susceptibility.### Competing Interest StatementThe authors have declared no competing interest.### Funding StatementThis study was supported by the Victorian Government and Medical Research Future Fund (MRFF) GNT2002073 (to A.K.W, P.M.H., W.H.T., D.I.G., S.J.K., and A.W.C.), GNT2005544 (to A.K.W., J.A.J., D.I.G., S.J.K., and A.W.C), the Paul Ramsay Foundation (A.K.W., D.I.G., S.J.K. and A.W.C.). A.K.W, J.A.J., D.I.G., W.H.T., S.J.K. and A.W.C. are supported by NHMRC fellowships. W-H.T. is a Howard Hughes Medical Institute Wellcome Trust International Research Scholar (208693/Z/17/Z). N.A.G. is supported by an ARC DECRA fellowship.### Author DeclarationsI confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.YesThe details of the IRB/oversight body that provided approval or exemption for the research described are given below:Study protocols were approved by the University of Melbourne Human Research Ethics Committee (#2056689).I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.YesI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).YesI have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable.YesAll data produced in the present work are contained in the manuscript

Abstract 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.

Immunoglobulin A (IgA) vasculitis is an autoimmune disease associated with bacterial and viral infections that typically presents with palpable purpura, arthralgia, abdominal pain, and renal involvement. Coronavirus disease 2019 (COVID-19) infection has been found to trigger numerous autoimmune and rheumatologic conditions, including IgA vasculitis. We report a patient who had a COVID-19 infection and then two weeks later developed severe abdominal pain, nausea, emesis, diarrhea, hematochezia, palpable purpura, and arthralgia. Skin biopsy revealed deposition of IgA and C3 complement granular deposition with fibrinogen deposition in superficial dermal vessel walls consistent with IgA vasculitis. The patient was treated with intravenous methylprednisolone followed by oral prednisone with significant improvement and no relapse after tapering and discontinuing steroids in six weeks. This case of biopsy-proven IgA vasculitis precipitated by active COVID-19 infection demonstrates the ability of COVID-19 infection to induce IgA vasculitis and its response to corticosteroid treatment.

Allelic variants are found amongst all human IgG subclasses and can influence a range of Fc functions. IgG allotypes have been associated with reduced risk of clinical malaria, an ancient disease that has co-evolved with humanity. However, how they contribute to malaria control is not fully understood. Here, we identified a novel IgG3 allotype in pregnant women from Papua New Guinea who were highly exposed to malaria. The new G3m29 (IGHG3*30) allotype was prominent in women of Sepik ethnicity. Plasma from women with G3m29 induced enhanced antibody-dependent phagocytosis of Plasmodium falciparum CS2-infected erythrocytes. A human monoclonal antibody to P. falciparum VAR2CSA, recombinantly generated as IGHG3*30, showed enhanced affinity to FcγRIIa and induced increased antibody-dependent phagocytosis in comparison to other IgG3 allotypes. This study provides clues to the role of allotypic variants of IgG3 in the control of malaria.

Abstract Objectives SARS‐CoV‐2 can be transmitted by aerosols, and the ocular surface may be an important route of transmission. Little is known about protective antibody responses to SARS‐CoV‐2 in tears after infection or vaccination. We analysed the SARS‐CoV‐2‐specific IgG and IgA responses in human tears after either COVID‐19 infection or vaccination. Methods We measured the antibody responses in 16 subjects with COVID‐19 infection for an average of 7 months before, and 15 subjects before and 2 weeks post‐Comirnaty (Pfizer‐BioNtech) vaccination. Plasma, saliva and basal tears were collected. Eleven pre‐pandemic individuals were included as healthy controls. Results IgG antibodies to spike and nucleoprotein were detected in tears, saliva and plasma from subjects with prior SARS‐CoV‐2 infection in comparison with uninfected controls. While receptor‐binding domain (RBD)‐specific antibodies were detected in plasma, minimal RBD‐specific antibodies were detected in tears and saliva. By contrast, high levels of IgG antibodies to spike and RBD, but not nucleoprotein, were induced in tears, saliva and plasma of subjects receiving 2 doses of the Comirnaty vaccine. Increased levels of IgA1 and IgA2 antibodies to SARS‐CoV‐2 antigens were detected in plasma following infection or vaccination but were unchanged in tears and saliva. Comirnaty vaccination induced high neutralising Abs in the plasma, but limited neutralising antibodies were detected in saliva or tears. Conclusion Both infection and vaccination induce SARS‐CoV‐2‐specific IgG antibodies in tears. RBD‐specific IgG antibodies in tears were induced by vaccination but were not present 7 months post‐infection. This suggests the neutralising antibodies may be low in the tears late following infection.

The SARS-CoV-2 receptor binding domain (RBD) is both the principal target of neutralizing antibodies and one of the most rapidly evolving domains, which can result in the emergence of immune escape mutations, limiting the effectiveness of vaccines and antibody therapeutics. To facilitate surveillance, we developed a rapid, high-throughput, multiplex assay able to assess the inhibitory response of antibodies to 24 RBD natural variants simultaneously. We demonstrate how this assay can be implemented as a rapid surrogate assay for functional cell-based serological methods to measure the SARS-CoV-2 neutralizing capacity of antibodies at the angiotensinconverting enzyme 2-RBD (ACE2-RBD) interface. We describe the enhanced affinity of RBD variants N439K, S477N, Q493L, S494P, and N501Y to the ACE2 receptor and demonstrate the ability of this assay to bridge a major gap for SARS-CoV-2 research, informing selection of complementary monoclonal antibody candidates and the rapid identification of immune escape to emerging RBD variants following vaccination or natural infection.

The capacity of antibodies to engage with immune cells via the Fc region is important in preventing and controlling many infectious diseases. The evolution of such antibodies during convalescence from coronavirus disease 2019 (COVID-19) is largely unknown. We develop assays to measure Fc-dependent antibody functions against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S)-expressing cells in serial samples from subjects primarily with mild-moderate COVID-19 up to 149 days post-infection. We find that S-specific antibodies capable of engaging Fcγ receptors decay over time, with S-specific antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent phagocytosis (ADP) activity within plasma declining accordingly. Although there is significant decay in ADCC and ADP activity, they remain readily detectable in almost all subjects at the last time point studied (94%) in contrast with neutralization activity (70%). Although it remains unclear the degree to which Fc effector functions contribute to protection against SARS-CoV-2 re-infection, our results indicate that antibodies with Fc effector functions persist longer than neutralizing antibodies.

The hallmarks of COVID-19 are higher pathogenicity and mortality in the elderly compared to children. Examining baseline SARS-CoV-2 cross-reactive immunological responses, induced by circulating human coronaviruses (hCoVs), is needed to understand such divergent clinical outcomes. Here we show analysis of coronavirus antibody responses of pre-pandemic healthy children (n=89), adults (n=98), elderly (n=57), and COVID-19 patients (n=50) by systems serology. Moderate levels of cross-reactive, but non-neutralizing, SARS-CoV-2 antibodies are detected in pre-pandemic healthy individuals. SARS-CoV-2 antigen-specific Fc gamma receptor binding accurately distinguishes COVID-19 patients from healthy individuals, suggesting that SARS-CoV-2 infection induces qualitative changes to antibody Fc, enhancing Fc gamma receptor engagement. Higher cross-reactive SARS-CoV-2 IgA and IgG are observed in healthy elderly, while healthy children display elevated SARS-CoV-2 IgM, suggesting that children have fewer hCoV exposures, resulting in less-experienced but more polyreactive humoral immunity. Age-dependent analysis of COVID-19 patients, confirms elevated class-switched antibodies in elderly, while children have stronger Fc responses which we demonstrate are functionally different. These insights will inform COVID-19 vaccination strategies, improved serological diagnostics and therapeutics. Antibody responses to SARS-CoV-2 are critical in the immune response to infection, but the potential cross-reactivity to other human corona viruses is poorly appreciated. Here the authors apply a systems based approach to characterise the antibody response in pre-pandemic cohorts and assess heterotypic reactivity to SARS-CoV-2.

Femur shaft and neck of femur (NOF) fractures are often undertreated in the prehospital setting. These injuries can present unique clinical and logistical concerns in the prehospital setting. This systematic review aimed to investigate paramedic prehospital pain management of patients who had suffered NOF or femur fractures, and to investigate which interventions are effective. A systematic review was conducted in line with Preferred Reporting Item for Systematic Reviews and Meta-Analyses guidelines. Four databases were searched from inception date 23 March 2020. Articles were independently reviewed by two authors and conflicts resolved by a third author, followed by a hand search of the included reference lists. References were included if they addressed paramedic interventions for NOF or femur shaft fractures. Outcomes of interest were the effectiveness and complications of different modalities administered by paramedics. The search yielded 6868 articles, of which 19 met the final inclusion criteria. Studies investigated a variety of interventions including traction splints, intravenous (IV) analgesia and alternative analgesic options. Traction splinting and IV analgesia were consistently reported as underutilised. Alternative analgesics such as auricular acupressure, transcutaneous electrical nerve stimulation (TENS) and fascia iliaca compartment block were found to be effective techniques that could be safely and competently employed by paramedics, reducing pain for patients with limited adverse events. NOF and femur shaft fractures are an undertreated injury in the prehospital setting. Traction splinting and IV analgesia remain the traditional methodologies of treatment for these injuries; however, there are alternatives such as TENS, auricular acupressure and fascia iliaca compartment block that appear to be emerging as safe and effective options for the prehospital setting.

The durability of infection-induced SARS-CoV-2 immunity has major implications for reinfection and vaccine development. Here, we show a comprehensive profile of antibody, B cell and T cell dynamics over time in a cohort of patients who have recovered from mild-moderate COVID-19. Binding and neutralising antibody responses, together with individual serum clonotypes, decay over the first 4 months post-infection. A similar decline in Spike-specific CD4+ and circulating T follicular helper frequencies occurs. By contrast, S-specific IgG+ memory B cells consistently accumulate over time, eventually comprising a substantial fraction of circulating the memory B cell pool. Modelling of the concomitant immune kinetics predicts maintenance of serological neutralising activity above a titre of 1:40 in 50% of convalescent participants to 74 days, although there is probably additive protection from B cell and T cell immunity. This study indicates that SARS-CoV-2 immunity after infection might be transiently protective at a population level. Therefore, SARS-CoV-2 vaccines might require greater immunogenicity and durability than natural infection to drive long-term protection.