Cross-reactive Protein Research Articles

Component-resolved diagnostics of fruit and vegetable allergy: precise identification and individualized treatment strategies

Vegetable and fruit allergies are common types of food allergies worldwide, most of them are triggered by primary sensitization to pollen. Most allergens in vegetables and fruits belong to a few cross-reactive proteins such as PR-10 proteins, profilins, and nsLTPs. The presence of these allergens in various plants can lead to widespread cross-reactive allergic responses. Component-resolved diagnostics (CRD) can improve diagnostic accuracy by precisely identifying specific allergenic proteins, aiding physicians in making more accurate treatment and management decisions, and reducing unnecessary food avoidance. This article, based on the "Molecular Allergology User's Guide 2.0 (MAUG 2.0)" issued by the European Academy of Allergy and Clinical Immunology (EAACI), analyzes the primary mechanisms, relevant allergens, and diagnostic and clinical management strategies for vegetable and fruit allergies. By detailing and analyzing these allergenic components, this article may help the healthcare professionals to deep the understandings of vegetable and fruit allergies, offer new perspectives and practical guideline for the research and treatment of these allergies, and promot the development of precise diagnostics and personalized treatment strategies.

Pollen Cross-Reactivity: A Primer for Allergy Specialists

There are over 400,000 land-based plant species that comprise our biodiverse habitat. Only a small subset of those plant species satisfies Thommen’s postulates, classifying them as allergens. The number of allergenic species, however, remains so vast that it is prohibitive to both test and treat for all relevant species within a geographical region. Allergy specialists have a valuable tool that can be used to help simplify the management of allergic patients: cross-reactivity. Cross-reactivity is the ability for an allergen to induce an IgE-mediated response, regardless of previous exposure. Allergens are a complex milieu of proteins, some of which have allergic potential while others do not. A number of proteins are conserved across allergen species. When exposure to these conserved proteins occurs, the immune system recognizes them in a similar manner. For homologous or cross-reactive allergenic proteins, this conserved molecular recognition initiates the allergic cascade. Allergen characterization is critical to the understanding of cross-reactivity. Characterization, in this context, refers to the protein make-up of a particular allergen. The process of allergen characterization began in 1962 with the discovery of antigen E, the first identified allergenic protein. Antigen E, commonly known as Amb a 1, is an allergenic protein in ragweed, and is the primary sensitizing protein for ragweed allergy sufferers. These primary sensitizers are referred to as major allergens and can be defined as such when >50% of the allergic patient population is sensitized to them. An entire branch of research arose from this discovery, which has allowed for major advances to be made in the understanding of cross‑reactive relationships among allergen species. Cross‑reactivity is not limited to homologous major allergen expression. Rather, minor allergens and panallergens, though less clinically relevant, play a similar role in cross‑reactive relationships. This primer will explore the science behind cross‑reactivity, as well as provide a general overview of the cross‑reactive relationships that have been defined for plant allergens found across North America.

Identification of cross-reactive IgE-binding proteins from Philippine allergenic grass pollen extracts.

Respiratory allergies are one of the most common allergic diseases that affect Filipinos. Grass pollen accounts for the majority of the outdoor allergens triggering these respiratory allergies. Cross-reactivity among the Philippine grass pollen grains has not been extensively studied. This study aims to investigate the cross-reactivity of our local grasses and identify the cross-reactive allergens. Grass pollen grains were collected and processed into crude allergenic extracts. The IgE-reactivity of these crude allergenic pollen extracts was studied using sera from patients who tested positive for the mentioned extracts. The proteins from the immunoblots of cross-reactive pollen allergen extracts were sequenced and identified. Allergenic pollen proteins were identified as cross-reactive among the grass pollen extracts. Four of these have not been listed yet as grass allergens in the World Health Organization/International Union of Immunological Societies allergen nomenclature database. Local grass pollen allergens are cross-reactive with probable new allergens identified.

Efficacy and safety evaluation of cross-reactive Fibroblast activation protein scFv-based CAR-T cells.

Fibroblast activation protein (FAP) overexpression on cancer-associated fibroblasts (CAFs) is associated with poor prognosis and worse clinical outcomes. Selective ablation of pro-tumorgenic FAP+ stromal cells with CAR-T cells may be a new therapeutic strategy. However, the clinical use of FAP-CAR T cells is suggested to proceed with caution for occasional poor efficacy and induction of on-target off-tumor toxicity (OTOT), including lethal osteotoxicity and cachexia. Hence, more investigations and preclinical trials are required to optimize the FAP-CAR T cells and to approve their safety and efficacy. In this study, we designed second-generation CAR T cells targeting FAP with 4-1BB as a co-stimulatory molecule, and tested their cytotoxicity against FAP-positive cells (hFAP-HT1080 cells and a variety of primary CAFs) in vitro and in Cell line-derived xenograft (CDX) and a patient-derived xenograft (PDX) model. Results showed that our FAP-CAR T cells were powerfully potent in killing human and murine FAP-positive tumor cells and CAFs in multiple types of tumors in BALB/c and C57BL/6 mice and in patient-derived xenografts (PDX) model. And they were proved to be biologically safe and exhibit low-level OTOT. Taken together, the human/murine cross-reactive FAP-CAR T cells were powerfully potent in killing human and murine FAP positive tumor cells and CAFs. They were biologically safe and exhibit low-level OTOT, warranting further clinical investigation into our FAP-CAR T cells.

Screening asthmatics for atopic status using the ALergy EXplorer (ALEX2) macroarray

Background Screening asthma patients for atopy facilitates management. Since 2010, the core biomarker for screening asthma subjects for atopic status has been the qualitative Phadiatop. multi-aeroallergen screen. A more quantitative macroarray, the Allergy Explorer (ALEX2), shows promise as an alternative. Objective The study’s goal was to examine the pros and cons of the use of ALEX2 in the screening of asthma patients for atopic status. Methods We evaluated the atopic (IgE-sensitization) status in asthmatic Amish and Hutterite farm children using the ImmunoCAP and ALEX2 assays in Phadiatop equivocal and positive subjects. Results All 42 asthmatic children were analyzed by Phadiatop and total serum IgE. Of these, 22 had a negative Phadiatop (<0.1 kUa/L) and total IgE <100 kU/L which defined them as non-atopic and they were excluded from ALEX2 testing. Of six children with equivocal Phadiatops (0.1–0.2 kUa/L-Group 1) and three children with a negative Phadiatop but total IgE >100 kUa/L (group 3), 44% (n = 4) had detectable IgE antibody by ALEX2 to mite, tree pollen, and other allergens not detected by Phadiatop, but confirmed by allergen-specific ImmunoCAP testing. In 11 Phadiatop positive subjects (>0.2 kUa/L–group 2), all but one were positive by ALEX2. IgE antibody specific for mold and rabbit aeroallergens matched their agricultural and pet exposure history. Three children were positive for IgE antibody to allergens in the profilin, nsLTP, or PR-10 cross-reactive protein families. Conclusion Judicious use of ALEX2’s enhanced specificity data not provided by the Phadiatop can aid in the interpretation of sensitization patterns and planning management of atopic asthmatics, but sensitization relevance must be confirmed by the patient’s clinical history.

Gastrointestinal manifestations, spectrum and frequency of sensitization to food allergens in Kyiv’s adult citizens with allergic rhinitis: a cross-sectional study

Background. Food allergy affects 1–3 % of adults worldwide. More than 160 foods can cause allergic reactions. Food allergy may precede and stimulate allergic rhinitis. Aim of the study was to assess the spectrum and frequency of sensitization to food allergens in patients with allergic rhinitis from Kyiv, Ukraine. Materials and me­thods. The investigation was conducted as a cross-sectional study. One hundred and seventy-five Kyiv adult patients with allergic rhinitis were enrolled in the trial. Sensitization to allergens and their components was determined by skin prick tests and in vitro detection of allergen specific IgE by ELISA in blood serum — a multicomponent Allergy Explorer2 ALEX2 test. Results. It was shown that sensitization to following inhalant allergens was predominant: to timothy grass — in 50.3 %, to ragweed — in 48.6 %, to birch — in 44 %, to wormwood — in 24 %, to Alternaria alternata mold — in 15.4 % of patients. One hundred and thirty-one (74.9 %) participants have co-sensitization to at least one food allergen, among them 77 (58.8 %) had gastrointestinal symptoms. Sensitization to following food allergens was predominant: to hazelnut — 27.5 %, apple — 26.3 %, peanut — 21.7 %, celery — 14.3 %, soy — 13.1 %, carp — 11.4 %, kiwi — 9.1 %, crab — 9.1 %, codfish — 8.6 %, oyster — 8.6 %, peach — 8 %, lobster — 8 %, carrot — 7.4 %, anisakis — 6.3 %, prawn — 6.3 %, tiger prawn — 5.7 %, to beef — 5.1 % of cases. It was found that the frequency of sensitization to cross-reactive proteins PR-10 was 20.5 % (95% confidence interval (CI); 9.7–33.9 %) in patients with allergic rhinitis without food co-sensitization comparing to 51.1 % (95% CI; 42.5–59.7 %) in participants with both allergic rhinitis and food co-sensitization, p &lt; 0.001; to nsLTP — 2.3 % (95% CI; 0–8.9 %) and 19.8 % (95% CI; 13.4–27.2 %), respectively, p = 0.011. Conclusions. Among Kyiv adult patients with allergic rhinitis, approximately three quarters have food co-sensitization that may be the cause of gastrointestinal symptoms and exacerbations of allergic rhinitis after consuming vegetables, fruits and nuts due to cross-reactivity with inhalant allergens. This should be considered when manage such patients.

Expression and functional characterization of bovine receptor activator of NF-κB ligand (RANKL)

Receptor activator of nuclear factor Kappa-B Ligand (RANKL) is a member of the tumor necrosis factor ligand (TNF) family involved in immune responses and immunomodulation. Expressed in various cells types around the body, RANKL plays a crucial role in bone remodeling and development of the thymus, lymph nodes and mammary glands. Research in other species demonstrates that RANKL is required for the development of microfold cells (M cells) in the gut, however limited information specific to cattle is available. Cloning and expression of bovine RANKL (BoRANKL) was carried out and bioactivity of the protein was demonstrated in the induction of osteoclast differentiation from both bovine and ovine bone marrow cells. The effects of BoRANKL on particle uptake in bovine enteroids was also assessed. The production of cross-reactive bovine RANKL protein will enable further investigations into cell differentiation using the available ruminant organoid systems, and their role in investigating host-pathogen interactions in cattle and sheep.

Development of a novel serological assay for the detection of mpox infection in vaccinated populations.

In 2022 the World Health Organization declared a Public Health Emergency for an outbreak of mpox, the zoonotic Orthopoxvirus (OPV) affecting at least 104 nonendemic locations worldwide. Serologic detection of mpox infection is problematic, however, due to considerable antigenic and serologic cross-reactivity among OPVs and smallpox-vaccinated individuals. In this report, we developed a high-throughput multiplex microsphere immunoassay using a combination of mpox-specific peptides and cross-reactive OPV proteins that results in the specific serologic detection of mpox infection with 93% sensitivity and 98% specificity. The New York State Non-Vaccinia Orthopoxvirus Microsphere Immunoassay is an important tool to detect subclinical mpox infection and understand the extent of mpox spread in the community through retrospective analysis.

Structural Characterization of Food Allergens by Nuclear Magnetic Resonance Spectroscopy.

As allergies, especially those triggered by food, are becoming more and more prevalent, it is of increasing importance to fully understand the structures and dynamic behaviors of allergenic proteins along with their interactions with potential natural ligands. Therefore, we have established a solid routine to achieve structural characterization of food allergens, especially for birch pollen-related cross-reactive proteins from the class 10 of pathogenesis-related proteins (PR-10), by nuclear magnetic resonance (NMR) spectroscopy. Following expression of the desired allergen in Escherichia coli in isotope-labeled minimal media, the three-dimensional solution structures of these proteins can be determined, and insight into ligand binding mechanics and structural dynamic properties are accessible through NMR spin relaxation experiments.

Murine model identifies tropomyosin as IgE cross-reactive protein between house dust mite and coho salmon that possibly contributes to the development of salmon allergy.

Recently, we have developed a method to identify IgE cross-reactive allergens. However, the mechanism by which IgE cross-reactive allergens cause food allergy is not yet fully understood how. In this study, we aimed to understand the underlying pathogenesis by identifying food allergens that cross-react with house dust mite allergens in a murine model. Allergenic protein microarray analysis was conducted using serum from mice intraperitoneally injected with Dermatophagoides pteronyssinus (Der p) extract plus alum or alum alone as controls. Der p, Dermatophagoides farinae (Der f), coho salmon extract-sensitized and control mice were analyzed. Serum levels of IgE against Der p, Der f, coho salmon extract, protein fractions of coho salmon extract separated by ammonium sulfate precipitation and anion exchange chromatography, and recombinant coho salmon tropomyosin or actin were measured by an enzyme-linked immunosorbent assay. A murine model of cutaneous anaphylaxis or oral allergy syndrome (OAS) was established in Der p extract-sensitized mice stimulated with coho salmon extract, tropomyosin, or actin. Protein microarray analysis showed that coho salmon-derived proteins were highly bound to serum IgE in Der p extract-sensitized mice. Serum IgE from Der p or Der f extract-sensitized mice was bound to coho salmon extract, whereas serum IgE from coho salmon extract-sensitized mice was bound to Der p or Der f extract. Analysis of the murine model showed that cutaneous anaphylaxis and oral allergic reaction were evident in Der p extract-sensitized mice stimulated by coho salmon extract. Serum IgE from Der p or Der f extract-sensitized mice was bound strongly to protein fractions separated by anion exchange chromatography of coho salmon proteins precipitated with 50% ammonium sulfate, which massively contained the approximately 38 kDa protein. We found that serum IgE from Der p extract-sensitized mice was bound to recombinant coho salmon tropomyosin. Der p extract-sensitized mice exhibited cutaneous anaphylaxis in response to coho salmon tropomyosin. Our results showed IgE cross-reactivity of tropomyosin between Dermatophagoides and coho salmon which illustrates salmon allergy following sensitization with the house dust mite Dermatophagoides. Our method for identifying IgE cross-reactive allergens will help understand the underlying mechanisms of food allergies.

Lateral Flow Immunoassay As Novel Screening Tool For Potential Cross-Reacting Protein In Crude Plant Latex As Tested For Plasmodium, Dengue, HBV, HCV, HIV

Lateral Flow Immunoassay As Novel Screening Tool For Potential Cross-Reacting Protein In Crude Plant Latex As Tested For Plasmodium, Dengue, HBV, HCV, HIV

Assessment of Enterovirus Antibodies during Early Childhood Using a Multiplex Immunoassay.

Enteroviruses are a group of positive single-stranded viruses that belong to the Picornaviridae family. They regularly infect humans and cause symptoms ranging from the common cold and hand-foot-and-mouth disease to life-threatening conditions, such as dilated cardiomyopathy and poliomyelitis. Enteroviruses have also been associated with chronic immune-mediated diseases, such as type 1 diabetes, celiac disease, and asthma. Studying these disease-pathogen connections is challenging due to the high prevalence of enterovirus infections in the population and the transient appearance of the virus during the acute infection phase, which limit the identification of the causative agent via methods based on the virus genome. Serological assays can detect the antibodies induced by acute and past infections, which is useful when direct virus detection is not possible. We describe in this immuno-epidemiological study how the antibody levels against VP1 proteins from eight different enterovirus types, representing all seven of the human infecting enterovirus species, vary over time. VP1 responses first significantly (P < 0.001) decline until 6 months of age, reflecting maternal antibodies, and they then start to increase as the infections accumulate and the immune system develops. All 58 children in this study were selected from the DiabImmnune cohort for having PCR-confirmed enterovirus infections. Additionally, we show that there is great, although not complete, cross-reactivity of VP1 proteins from different enteroviruses and that the response against 3C-pro could reasonably well reflect the recent Enterovirus infection history (ρ = 0.94, P = 0.017). The serological analysis of enterovirus antibodies in sera from children paves the way for the development of tools for monitoring the Enterovirus epidemics and associated diseases. IMPORTANCE Enteroviruses cause a wide variety of symptoms ranging from a mild rash and the common cold to paralyzing poliomyelitis. While enteroviruses are among the most common human pathogens, there is a need for new, affordable serological assays with which to study pathogen-disease connections in large cohorts, as enteroviruses have been linked to several chronic illnesses, such as type 1 diabetes mellitus and asthma exacerbations. However, proving causality remains an issue. In this study, we describe the use of an easily customizable multiplexed assay that is based on structural and nonstructural enterovirus proteins to study antibody responses in a cohort of 58 children from birth to 3 years of age. We demonstrate how declining maternal antibody levels can obscure the serological detection of enteroviruses before the age of six months and how antibody responses to nonstructural enterovirus proteins could be interesting targets for serodiagnosis.

Une anaphylaxie sévère à la mangue dans le cadre d’un syndrome armoise-apiaceae-mangue chez une enfant de 11 ans

Mango allergy is rare but tends to increase due to the more frequent consumption of exotic fruits. We report the observation of an 11-year-old child who had severe anaphylaxis after eating a whole mango with a grade 3 reaction according to the Ring and Behrendt classification. She had already consumed it before without any reaction. She also had rhino-conjunctivitis for several years due to mugwort pollen, revealing the mugwort-apiaceae-mango syndrome. The mango skin prick test was positive at 4mm for native fresh fruit and 5mm for industrial mango juice. Specific IgE for mango and mugwort were 1.45 and 26.7kU/L, respectively. She also showed sensitization for some apiaceae, carrots and celery at 1.66 and 0.72kU/L respectively, that she consumed without any problem. In the presence of a mango allergy, it is advisable to look for cross-reactions with other allergens due to the cross-reactivity of mango proteins with respiratory and food allergens in the context of mugwort-apiaceae-mango syndrome.

Impact of individual molecular components in determining primary sensitization to latex

Allergy to natural rubber latex emerged as one of the main allergies at the beginning among some professional groups and the general population. Sensitization and development of latex allergy have been attributed to exposure to products containing residual latex proteins. The prevailing cross-reactivity of latex proteins with other food allergens is of great concern. Numerous purified allergens are currently available, which greatly help in patient management, thus determining their specific profile. We conducted a multicenter study to investigate changes, from the ROC analysis, in the characteristics of patients with latex allergy by measuring its major protein components. Sensitization to latex proteins is crucial because it highlights the cross reactivity to inhalants (pollen) and food (fruit). It is very essential in an accurate and specific clinical setting.

Corroboration of cross-reactivity between Mycobacterium leprae and hosts' salivary and cutaneous proteins: A hope for prognostic biomarkers for the pathogenesis of reactions in leprosy.

Immunological reactions are frequent complications that may occur either before, during, or after treatment and affect 30-50% of leprosy patients. The presence of autoantibodies like rheumatoid factor, antinuclear factor, and antibodies to host collagen, keratin, actin, myosin, endothelial cells, and myelin basic protein (MBP) has been earlier reported in leprosy patients. The purpose of this study was to identify cross-reactive proteins in clinical samples such as saliva and slit skin scrapings (SSS) of leprosy patients which could be utilised as prognostic biomarkers for Type 1 Reaction (T1R) in leprosy. A total of 10 leprosy patients in T1R and 5 healthy volunteers were recruited. The protein was extracted from their SSS and saliva samples, thereafter, isoelectric focusing (IEF) and two-dimensional PAGE were performed to analyse the proteins. Furthermore, the cross-reactivity was identified by western blotting host proteins in gel against purified IgG from Mycobacterium leprae soluble antigen (MLSA)- hyperimmunized rabbit sera, thereafter, cross-reactive proteins were identified by MS/MS. The cross-reactive host proteins were analysed for homologous bacterial proteins and B cell epitopes (BCEs) were predicted by using bioinformatic tools. A total of five spots of salivary proteins namely S100-A9, 35.3 kDa, and 41.5 kDa proteins, Serpin peptidase inhibitor (clade A), Cystatin SA-III, and four spots of SSS namely 41.4 kDa protein, Alpha-1 antitrypsin, vimentin, and keratin 1, were identified as cross-reactive. Further, a total of 22 BCEs of cross-reactive host proteins were predicted and visualised. This data provides strong evidence of cross-reactivity/molecular mimicry between host and pathogen in leprosy patients with reaction. These BCEs of cross-reactive proteins could be further studied to predict reactions and may be utilised as an early diagnostic biomarker for T1R in leprosy.

Prevalence and correlates of co-occurring allergies in a US food allergy patient registry

Food allergy (FA) affects an estimated 8% of children and 11% of adults.1,2 Population-level survey data suggest that 45.3% of adults and 39.9% of children having FAs are allergic to multiple foods and that racial and ethnic minorities have the highest prevalence of FA in childhood.1,2 Although the cross-reactivity of specific food proteins has been established, much less is known about its clinical relevance and association with sociodemographic characteristics.3 Here, we present the degree to which common cross-reactive food proteins are reported as co-occurring FAs and the associated sociodemographic characteristics in a large food-allergic patient registry.

Cross-reactivity between vaccine antigens from the chitin deacetylase protein family improves survival in a mouse model of cryptococcosis.

Meningitis due to the fungal pathogen Cryptococcus neoformans is estimated to cause nearly 200,000 deaths annually, mostly in resource-limited regions. We previously identified cryptococcal protein antigens which, when delivered in glucan particles, afford vaccine-mediated protection against an otherwise lethal infection. Many of these proteins exhibit significant homology to other similar cryptococcal proteins leading us to hypothesize that protection may be augmented by immunologic cross-reactivity to multiple members of a protein family. To examine the significance of protein cross-reactivity in vaccination, we utilized strains of Cryptococcus that are genetically deficient in select antigens, yet are still lethal in mice. Vaccination with a protein without homologs (e.g., Mep1 and Lhc1) protected against challenge with wild-type Cryptococcus, but not against a deletion strain lacking that protein. Contrastingly, vaccination with a single chitin deacetylase (Cda) protein protected against the corresponding deletion strain, presumably due to host recognition of one or more other family members still expressed in this strain. Vaccination with a single Cda protein induced cross-reactive antibody and interferon-gamma (IFNγ) immune responses to other Cda protein family members. Paradoxically, we saw no evidence of cross-protection within the carboxypeptidase family of proteins. Factors such as in vivo protein expression and the degree of homology across the family could inform the extent to which vaccine-mediated immunity is amplified. Together, these data suggest a role for prioritizing protein families in fungal vaccine design: increasing the number of immune targets generated by a single antigen may improve efficacy while diminishing the risk of vaccine-resistant strains arising from gene mutations.

In silico tools to assess the potential allergenicity of shiitake mushrooms (Lentinula edodes).

Computational tools may have an edge over conventional methods for the preliminary evaluation of food allergenicity. In this study, the allergenic potential of Lentinula edodes was evaluated and validated using in silico tools. The potential cross-reactivity of mushroom proteins with fungal allergens was determined using sequence alignment - the Fast Alignment(FASTA) and Basic Local Alignment Search Tool (BLAST) algorithm. Eight L. edodes proteins were cross-reactive with allergens from fungal origin, showing 52%-89% sequence identity using FASTA algorithm-based alignment. The BLAST data were corroborated by percentage identity and query coverage. Physico-chemical property-based allergenicity was deciphered by AlgPred, Allermatch, and AllergenFP software, which predicted six out of eight proteins as potential allergens. Sequence alignment showed 66%-86% conservancy between mushroom protein and known fungal allergens. Secondary structure and amino acid composition supported structural affinity between query and fungal proteins. Three-dimensional structures of five mushroom proteins were generated, quality assessed, and superimposed with fungal allergens, suggesting possible allergenicity of mushroom proteins. An enzyme-linked immunosorbent assay (ELISA) demonstrated immunoglobulin E (IgE) binding in 13 out of 21 food-hypersensitive patients' sera. In silico tools provide preliminary indications about the potential allergenicity and cross-reactivity of mushroom proteins. This approach may be used for the prelusive allergenicity assessment of allergen sources. © 2022 Society of Chemical Industry.

Preexisting antibodies targeting SARS-CoV-2 S2 cross-react with commensal gut bacteria and impact COVID-19 vaccine induced immunity

ABSTRACT The origins of preexisting SARS-CoV-2 cross-reactive antibodies and their potential impacts on vaccine efficacy have not been fully clarified. In this study, we demonstrated that S2 was the prevailing target of the preexisting S protein cross-reactive antibodies in both healthy human and SPF mice. A dominant antibody epitope was identified on the connector domain of S2 (1147-SFKEELDKYFKNHT-1160, P144), which could be recognized by preexisting antibodies in both human and mouse. Through metagenomic sequencing and fecal bacteria transplant, we demonstrated that the generation of S2 cross-reactive antibodies was associated with commensal gut bacteria. Furthermore, six P144 reactive monoclonal antibodies were isolated from naïve SPF mice and were proven to cross-react with commensal gut bacteria collected from both human and mouse. A variety of cross-reactive microbial proteins were identified using LC-MS, of which E. coli derived HSP60 and HSP70 proteins were confirmed to be able to bind to one of the isolated monoclonal antibodies. Mice with high levels of preexisting S2 cross-reactive antibodies mounted higher S protein specific binding antibodies, especially against S2, after being immunized with a SARS-CoV-2 S DNA vaccine. Similarly, we found that levels of preexisting S2 and P144-specific antibodies correlated positively with RBD binding antibody titers after two doses of inactivated SARS-CoV-2 vaccination in human. Collectively, our study revealed an alternative origin of preexisting S2-targeted antibodies and disclosed a previously neglected aspect of the impact of gut microbiota on host anti-SARS-CoV-2 immunity.

Efficacy and safety of a universal influenza A vaccine (MVA-NP+M1) in adults when given after seasonal quadrivalent influenza vaccine immunisation (FLU009): a phase 2b, randomised, double-blind trial

In animal, epidemiological, and human challenge studies, a pre-existing T-cell response to internal proteins of influenza A has been associated with improved virological and disease outcomes. The aim of this study was to assess whether inducing additional responses to conserved CD4 and CD8 T-cell antigens provides added benefit to standard influenza vaccination. We designed a phase 2b, randomised, placebo-controlled, double-blind trial of a recombinant viral-vectored vaccine (modified vaccinia Ankara expressing virus nucleoprotein and matrix protein 1; MVA-NP+M1), which has been shown to induce both CD4 and CD8 T cells, at eight outpatient clinical trial sites in Australia over two consecutive influenza seasons. We recruited non-immunosuppressed adults (≥18 years) who had received the 2019 quadrivalent influenza vaccine (QIV) vaccine within 28 days before study enrolment and randomisation (day 0). Participants were randomly assigned (1:1) according to a computer-generated random sequence to receive one dose of 1·5 × 108 plaque-forming units of MVA-NP+M1 or saline (placebo) intramuscularly. Randomisation was stratified by age (<65 years or ≥65 years). The patients and trial assessors were masked to treatment assignment. During the subsequent influenza seasons, participants with symptoms related to respiratory illness or influenza-like illness were to attend the clinic within 72 h of symptom onset for two nasal swabs for influenza testing by quantitative RT-PCR. The primary endpoint was the incidence rate of laboratory-confirmed influenza in the intention-to-treat (ITT) population. Safety (solicited adverse events within 7 days and unsolicited adverse events within 28 days after study vaccination, and serious adverse events for the study duration) was assessed in all randomly assigned participants who received at least one vaccination (according to the treatment received). The trial is registered with ClinicalTrials.gov, NCT03880474. Between April 2 and June 14, 2019, 2152 adults were randomly allocated and received MVA-NP+M1 (n=1077) or placebo (n=1075), comprising the efficacy (ITT) analysis set. Participants were followed up throughout the 2019 Australia influenza season (May 1 to Oct 15, 2019). 419 (19·5%) of 2152 participants were aged 65 years or older. The incidence of laboratory-confirmed influenza did not differ between the MVA-NP+M1 group (35 of 1077 participants; 3·25% [95% CI 2·31-4·44]) and the placebo group (23 of 1075; 2·14% [1·39-3·14]; Fisher's exact p=0·14). 23 severe solicited local injection site reactions were reported in 13 (0·6%) of 2152 participants, 22 of which were reported in the MVA-NP + M1 group (in 12 [1·1%] participants). 100 severe systemic events were reported in 45 (4·2%) MVA-NP + M1 recipients, and 20 were reported in 14 (1·3%) placebo recipients. Three unsolicited grade 3 events in three participants (two headache and one nausea, all in the MVA-NP+M1 group) were deemed vaccine related. 21 serious adverse events were reported in 18 (1·7%) of 1077 participants in the MVA-NP+M1 group and 25 serious adverse events were reported in 22 (2·0%) of 1075 participants in the placebo group; none were considered vaccine related. The trial was stopped after one season for futility on the recommendation of the data monitoring committee. MVA-NP+M1 was well tolerated with no vaccine-associated serious adverse events. A vaccine designed to induce moderate T-cell responses to the cross-reactive internal proteins of influenza A did not lead to improved incidence when given within 28 days after standard QIV immunisation. A greater magnitude of T-cell response with a different vaccine or regimen, or localisation in the lungs via alternative delivery, such as intranasal or aerosol, might be successful and require further investigation. Vaccitech.