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Abstract Idiopathic chronic neutropenia (ICN) describes a heterogeneous group of hematologic diseases characterized by low circulating neutrophil levels often associated with recurrent fevers, chronic mucosal inflammation, and severe systemic infections. The severity and risk of complications, including serious infections, are inversely proportional to the absolute neutrophil count (ANC), with the greatest problems occurring in patients with an ANC of less than 0.5 × 109/L. This case report describes a 64-year-old female with longstanding rheumatoid arthritis who subsequently developed ICN with frequent episodes of sepsis requiring hospitalization and prolonged courses of antibiotics over a 4-year period. She was treated with granulocyte colony stimulating factors (G-CSF) but had a delayed, highly variable, and volatile response. She was enrolled in a clinical trial evaluating the oral investigational agent ezatiostat. Ezatiostat, a glutathione S-transferase P1-1 inhibitor, activates Jun kinase, promoting the growth and maturation of hematopoietic progenitor stem cells. She responded by the end of the first month of treatment with stabilization of her ANC (despite tapering and then stopping G-CSF), clearing of fever, and healing of areas of infection. This ANC response to ezatiostat treatment has now been sustained for over 8 months and continues. These results suggest potential roles for ezatiostat in the treatment of patients with ICN who are not responsive to G-CSF, as an oral therapy alternative, or as an adjunct to G-CSF, and further studies are warranted.

Virus neutralization profiles against primary infection sera and corresponding antigenic cartography are integral part of the COVID-19 and influenza vaccine strain selection processes. Human single variant exposure sera have previously defined the antigenic relationships among SARS-CoV-2 variants but are now largely unavailable due to widespread population immunity. Therefore, antigenic characterization of future SARS-CoV-2 variants will require an animal model, analogous to using ferrets for influenza virus. We evaluated neutralization profiles against 23 SARS-CoV-2 variants in nonhuman primates (NHPs) after single variant exposure and generated an NHP-derived antigenic map. We identified a distant antigenic region occupied by BA.2.86, JN.1, and the descendants KP.2, KP.3, and KZ.1.1.1. We also found that the monovalent XBB.1.5 mRNA vaccine induced broad immunity against the mapped antigenic space. In addition, substantial concordance was observed between our NHP-derived and two human antigenic maps, demonstrating the utility of NHPs as a surrogate for antigenic cartography in humans., Competing Interests: Declaration of interests J.K. is listed as an inventor on patents related to vesicular stomatitis virus-based oncolytic viruses., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Highly pathogenic avian influenza A(H5) viruses globally impact wild and domestic birds, and mammals, including humans, underscoring their pandemic potential. The antigenic evolution of the A(H5) hemagglutinin (HA) poses challenges for pandemic preparedness and vaccine design. Here, the global antigenic evolution of the A(H5) HA was captured in a high-resolution antigenic map. The map was used to engineer immunogenic and antigenically central vaccine HA antigens, eliciting antibody responses that broadly cover the A(H5) antigenic space. In ferrets, a central antigen protected as well as homologous vaccines against heterologous infection with two antigenically distinct viruses. This work showcases the rational design of subtype-wide influenza A(H5) pre-pandemic vaccines and demonstrates the value of antigenic maps for the evaluation of vaccine-induced immune responses through antibody profiles., Competing Interests: Competing interests: Authors declare that they have no competing interests.

Severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) has developed substantial antigenic variability. As the majority of the population now has pre-existing immunity due to infection or vaccination, the use of experimentally generated animal immune sera can be valuable for measuring antigenic differences between virus variants. Here, we immunized Syrian hamsters by two successive infections with one of nine SARS-CoV-2 variants. Their sera were titrated against 16 SARS-CoV-2 variants, and the resulting titers were visualized using antigenic cartography. The antigenic map shows a condensed cluster containing all pre-Omicron variants (D614G, Alpha, Delta, Beta, Mu, and an engineered B.1+E484K variant) and considerably more diversity among a selected panel of Omicron subvariants (BA.1, BA.2, BA.4/BA.5, the BA.5 descendants BF.7 and BQ.1.18, the BA.2.75 descendant BN.1.3.1, the BA.2-derived recombinants XBB.2 and EG.5.1, and the BA.2.86 descendant JN.1). Some Omicron subvariants were as antigenically distinct from each other as the wildtype is from the Omicron BA.1 variant. Compared to titers measured in human sera, titers in hamster sera are of higher magnitude, show less fold change, and result in a more compact antigenic map topology. The results highlight the potential of sera from hamsters for the continued antigenic characterization of SARS-CoV-2., Competing Interests: Competing interests statement:V.M.C. has his name on patents regarding SARS-CoV-2 serological testing and monoclonal antibodies.

Antigenic characterization of newly emerging SARS-CoV-2 variants is important to assess their immune escape and judge the need for future vaccine updates. To bridge data obtained from animal sera with human sera, we analyzed neutralizing antibody titers in human and hamster single infection sera in a highly controlled setting using the same authentic virus neutralization assay performed in one laboratory. Using a Bayesian framework, we found that titer fold changes in hamster sera corresponded well to human sera and that hamster sera generally exhibited higher reactivity., (© 2024. The Author(s).)

The evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) requires ongoing monitoring to judge the ability of newly arising variants to escape the immune response. A surveillance system necessitates an understanding of differences in neutralization titers measured in different assays and using human and animal serum samples. We compared 18 datasets generated using human, hamster, and mouse serum and six different neutralization assays. Datasets using animal model serum samples showed higher titer magnitudes than datasets using human serum samples in this comparison. Fold change in neutralization of variants compared to ancestral SARS-CoV-2, immunodominance patterns, and antigenic maps were similar among serum samples and assays. Most assays yielded consistent results, except for differences in fold change in cytopathic effect assays. Hamster serum samples were a consistent surrogate for human first-infection serum samples. These results inform the transition of surveillance of SARS-CoV-2 antigenic variation from dependence on human first-infection serum samples to the utilization of serum samples from animal models.

Importance: A/H7 avian influenza viruses cause outbreaks in poultry globally, resulting in outbreaks with significant socio-economical impact and zoonotic risks. Occasionally, poultry vaccination programs have been implemented to reduce the burden of these viruses, which might result in an increased immune pressure accelerating antigenic evolution. In fact, evidence for antigenic diversification of A/H7 influenza viruses exists, posing challenges to pandemic preparedness and the design of vaccination strategies efficacious against drifted variants. Here, we performed a comprehensive analysis of the global antigenic diversity of A/H7 influenza viruses and identified the main substitutions in the hemagglutinin responsible for antigenic evolution in A/H7N9 viruses isolated between 2013 and 2019. The A/H7 antigenic map and knowledge of the molecular determinants of their antigenic evolution add value to A/H7 influenza virus surveillance programs, the design of vaccines and vaccination strategies, and pandemic preparedness., Competing Interests: The authors declare no conflict of interest.

During the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, multiple variants escaping preexisting immunity emerged, causing reinfections of previously exposed individuals. Here, we used antigenic cartography to analyze patterns of cross-reactivity among 21 variants and 15 groups of human sera obtained after primary infection with 10 different variants or after messenger RNA (mRNA)-1273 or mRNA-1273.351 vaccination. We found antigenic differences among pre-Omicron variants caused by substitutions at spike-protein positions 417, 452, 484, and 501. Quantifying changes in response breadth over time and with additional vaccine doses, our results show the largest increase between 4 weeks and >3 months after a second dose. We found changes in immunodominance of different spike regions, depending on the variant an individual was first exposed to, with implications for variant risk assessment and vaccine-strain selection.

The antigenic evolution of SARS-CoV-2 requires ongoing monitoring to judge the immune escape of newly arising variants. A surveillance system necessitates an understanding of differences in neutralization titers measured in different assays and using human and animal sera. We compared 18 datasets generated using human, hamster, and mouse sera, and six different neutralization assays. Titer magnitude was lowest in human, intermediate in hamster, and highest in mouse sera. Fold change, immunodominance patterns and antigenic maps were similar among sera. Most assays yielded similar results, except for differences in fold change in cytopathic effect assays. Not enough data was available for conclusively judging mouse sera, but hamster sera were a consistent surrogate for human first-infection sera., Competing Interests: VMC: Named on patents regarding SARS-CoV-2 serological testing and monoclonal antibodies. MSD: Consultant for Inbios, Vir Biotechnology, Ocugen, Topspin Therapeutics, Moderna, and Immunome. The Diamond laboratory has received unrelated funding support in sponsored research agreements from Moderna, Vir Biotechnology, Generate Biomedicines, and Emergent BioSolutions. YK: Received unrelated funding support from Daiichi Sankyo Pharmaceutical, Toyama Chemical, Tauns Laboratories, Inc., Shionogi & Co. LTD, Otsuka Pharmaceutical, KM Biologics, Kyoritsu Seiyaku, Shinya Corporation, and Fuji Rebio. IE: Research grant and speakers fees from Moderna. BMe: Research grant from Moderna. GRS: Is on the GSK Vaccines Scientific Advisory Board. Oxford University holds intellectual property related to the Oxford-AstraZeneca vaccine. MS: Serves in an advisory role for Ocugen, Inc. SP: Reports that the Uniformed Services University (USU) Infectious Diseases Clinical Research Program (IDCRP), a US Department of Defense institution, and the Henry M. Jackson Foundation (HJF) were funded under a Cooperative Research and Development Agreement to conduct an unrelated phase III COVID-19 monoclonal antibody immunoprophylaxis trial sponsored by AstraZeneca. The HJF, in support of the USU IDCRP, was funded by the Department of Defense Joint Program Executive Office for Chemical, Biological, Radiological, and Nuclear Defense to augment the conduct of an unrelated phase III vaccine trial sponsored by AstraZeneca. Both trials were part of the U.S. Government COVID-19 response. Neither is related to the work presented here.

Vaccine protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection wanes over time, requiring updated boosters. In a phase 2, open-label, randomized clinical trial with sequentially enrolled stages at 22 US sites, we assessed safety and immunogenicity of a second boost with monovalent or bivalent variant vaccines from mRNA and protein-based platforms targeting wild-type, Beta, Delta and Omicron BA.1 spike antigens. The primary outcome was pseudovirus neutralization titers at 50% inhibitory dilution (ID 50 titers) with 95% confidence intervals against different SARS-CoV-2 strains. The secondary outcome assessed safety by solicited local and systemic adverse events (AEs), unsolicited AEs, serious AEs and AEs of special interest. Boosting with prototype/wild-type vaccines produced numerically lower ID 50 titers than any variant-containing vaccine against all variants. Conversely, boosting with a variant vaccine excluding prototype was not associated with decreased neutralization against D614G. Omicron BA.1 or Beta monovalent vaccines were nearly equivalent to Omicron BA.1 + prototype or Beta + prototype bivalent vaccines for neutralization of Beta, Omicron BA.1 and Omicron BA.4/5, although they were lower for contemporaneous Omicron subvariants. Safety was similar across arms and stages and comparable to previous reports. Our study shows that updated vaccines targeting Beta or Omicron BA.1 provide broadly crossprotective neutralizing antibody responses against diverse SARS-CoV-2 variants without sacrificing immunity to the ancestral strain. ClinicalTrials.gov registration: NCT05289037 ., (© 2023. The Author(s).)

Since emergence of the initial SARS-CoV-2 BA.1, BA.2 and BA.5 variants, Omicron has diversified substantially. Antigenic characterization of these new variants is important to analyze their potential immune escape from population immunity and implications for future vaccine composition. Here, we describe an antigenic map based on human single-exposure sera and live-virus isolates that includes a broad selection of recently emerged Omicron variants such as BA.2.75, BF.7, BQ, XBB and XBF variants. Recent Omicron variants clustered around BA.1 and BA.5 with some variants further extending the antigenic space. Based on this antigenic map we constructed antibody landscapes to describe neutralization profiles after booster immunization with bivalent mRNA vaccines based on ancestral virus and either BA.1 or BA.4/5. Immune escape of BA.2.75, BQ, XBB and XBF variants was also evident in bivalently boosted individuals, however, cross-neutralization was improved for those with hybrid immunity. Our results indicate that future vaccine updates are needed to induce cross-neutralizing antibodies against currently circulating variants., (© 2023. Springer Nature Limited.)

Several studies have shown that SARS-CoV-2 BA.1 omicron is an immune escape variant. Meanwhile, however, omicron BA.2 and BA.5 became dominant in many countries and replaced BA.1. As both have several mutations compared to BA.1, we analyzed whether BA.2 and BA.5 show further immune escape relative to BA.1. Here, we characterized neutralization profiles against the BA.2 and BA.5 omicron sub-variants in plasma samples from individuals with different history of exposures to infection/vaccination and found that unvaccinated individuals after a single exposure to BA.2 had limited cross-neutralizing antibodies to pre-omicron variants and to BA.1. Consequently, our antigenic map including all Variants of Concern and BA.1, BA.2 and BA.5 omicron sub-variants, showed that all omicron sub-variants are distinct to pre-omicron variants, but that the three omicron variants are also antigenically distinct from each other. The antibody landscapes illustrate that cross-neutralizing antibodies against the current antigenic space, as described in our maps, are generated only after three or more exposures to antigenically close variants but also after two exposures to antigenically distant variants. Here, we describe the antigenic space inhabited by the relevant SARS-CoV-2 variants, the understanding of which will have important implications for further vaccine strain adaptations., (© 2022. The Author(s).)

Background: Protection from SARS-CoV-2 vaccines wanes over time and is compounded by emerging variants including Omicron subvariants. This study evaluated safety and immunogenicity of SARS-CoV-2 variant vaccines., Methods: This phase 2 open-label, randomized trial enrolled healthy adults previously vaccinated with a SARS-CoV-2 primary series and a single boost. Eligible participants were randomized to one of six Moderna COVID19 mRNA vaccine arms (50µg dose): Prototype (mRNA-1273), Omicron BA.1+Beta (1 or 2 doses), Omicron BA.1+Delta, Omicron BA.1 monovalent, and Omicron BA.1+Prototype. Neutralization antibody titers (ID 50 ) were assessed for D614G, Delta, Beta and Omicron BA.1 variants and Omicron BA.2.12.1 and BA.4/BA.5 subvariants 15 days after vaccination., Results: From March 30 to May 6, 2022, 597 participants were randomized and vaccinated. Median age was 53 years, and 20% had a prior SARS-CoV-2 infection. All vaccines were safe and well-tolerated. Day 15 geometric mean titers (GMT) against D614G were similar across arms and ages, and higher with prior infection. For uninfected participants, Day 15 Omicron BA.1 GMTs were similar across Omicron-containing vaccine arms (3724-4561) and higher than Prototype (1,997 [95%CI:1,482-2,692]). The Omicron BA.1 monovalent and Omicron BA.1+Prototype vaccines induced a geometric mean ratio (GMR) to Prototype for Omicron BA.1 of 2.03 (97.5%CI:1.37-3.00) and 1.56 (97.5%CI:1.06-2.31), respectively. A subset of samples from uninfected participants in four arms were also tested in a different laboratory at Day 15 for neutralizing antibody titers to D614G and Omicron subvariants BA.1, BA.2.12.2 and BA.4/BA.5. Omicron BA.4/BA.5 GMTs were approximately one third BA.1 GMTs (Prototype 517 [95%CI:324-826] vs. 1503 [95%CI:949-2381]; Omicron BA.1+Beta 628 [95%CI:367-1,074] vs. 2125 [95%CI:1139-3965]; Omicron BA.1+Delta 765 [95%CI:443-1,322] vs. 2242 [95%CI:1218-4128] and Omicron BA.1+Prototype 635 [95%CI:447-903] vs. 1972 [95%CI:1337-2907)., Conclusions: Higher Omicron BA.1 titers were observed with Omicron-containing vaccines compared to Prototype vaccine and titers against Omicron BA.4/BA.5 were lower than against BA.1 for all candidate vaccines., Clinicaltrialsgov: NCT05289037.

The global emergence of many severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants jeopardizes the protective antiviral immunity induced after infection or vaccination. To address the public health threat caused by the increasing SARS-CoV-2 genomic diversity, the National Institute of Allergy and Infectious Diseases within the National Institutes of Health established the SARS-CoV-2 Assessment of Viral Evolution (SAVE) programme. This effort was designed to provide a real-time risk assessment of SARS-CoV-2 variants that could potentially affect the transmission, virulence, and resistance to infection- and vaccine-induced immunity. The SAVE programme is a critical data-generating component of the US Government SARS-CoV-2 Interagency Group to assess implications of SARS-CoV-2 variants on diagnostics, vaccines and therapeutics, and for communicating public health risk. Here we describe the coordinated approach used to identify and curate data about emerging variants, their impact on immunity and effects on vaccine protection using animal models. We report the development of reagents, methodologies, models and notable findings facilitated by this collaborative approach and identify future challenges. This programme is a template for the response to rapidly evolving pathogens with pandemic potential by monitoring viral evolution in the human population to identify variants that could reduce the effectiveness of countermeasures., (© 2022. Springer Nature Limited.)

Although mRNA vaccines encoding the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) prevent COVID-19, the emergence of new viral variants jeopardizes their efficacy. Here, we assessed the immunogenicity and protective activity of historical (mRNA-1273, designed for Wuhan-1 spike protein) or modified (mRNA-1273.351, designed for B.1.351 spike protein) Moderna mRNA vaccines in 129S2 and K18-hACE2 mice. Mice were immunized with either high-dose or low-dose formulations of the mRNA vaccines, where low-dose vaccination modeled suboptimal immune responses. Immunization with formulations at either dose induced neutralizing antibodies in serum against ancestral SARS-CoV-2 WA1/2020 and several virus variants, although serum titers were lower against the B.1.617.2 (Delta) virus. Protection against weight loss and lung pathology was observed with all high-dose vaccines against all viruses. However, low-dose formulations of the vaccines, which produced lower magnitude antibody and T cell responses, showed breakthrough lung infections with B.1.617.2 and development of pneumonia in K18-hACE2 mice. Thus, in individuals with reduced immunity after mRNA vaccination, breakthrough infection and disease may occur with some SARS-CoV-2 variants.

Although mRNA vaccines prevent COVID-19, variants jeopardize their efficacy as immunity wanes. Here, we assessed the immunogenicity and protective activity of historical (mRNA-1273, designed for Wuhan-1 spike) or modified (mRNA-1273.351, designed for B.1.351 spike) preclinical Moderna mRNA vaccines in 129S2 and K18-hACE2 mice. Immunization with high or low dose formulations of mRNA vaccines induced neutralizing antibodies in serum against ancestral SARS-CoV-2 and several variants, although levels were lower particularly against the B.1.617.2 (Delta) virus. Protection against weight loss and lung pathology was observed with all high-dose vaccines against all viruses. Nonetheless, low-dose formulations of the vaccines, which produced lower magnitude antibody and T cell responses, and serve as a possible model for waning immunity, showed breakthrough lung infection and pneumonia with B.1.617.2. Thus, as levels of immunity induced by mRNA vaccines decline, breakthrough infection and disease likely will occur with some SARS-CoV-2 variants, suggesting a need for additional booster regimens.

Influenza vaccines are usually non-adjuvanted but addition of adjuvant may improve immunogenicity and permit dose-sparing, critical for vaccine supply in the event of an influenza pandemic. The aim of this first-in-man study was to determine the effect of delta inulin adjuvant on the safety and immunogenicity of a reduced dose seasonal influenza vaccine. Healthy male and female adults aged 18-65years were recruited to participate in a randomized controlled study to compare the safety, tolerability and immunogenicity of a reduced-dose 2007 Southern Hemisphere trivalent inactivated influenza vaccine formulated with Advax™ delta inulin adjuvant (LTIV+Adj) when compared to a full-dose of the standard TIV vaccine which does not contain an adjuvant. LTIV+Adj provided equivalent immunogenicity to standard TIV vaccine as assessed by hemagglutination inhibition (HI) assays against each vaccine strain as well as against a number of heterosubtypic strains. HI responses were sustained at 3months post-immunisation in both groups. Antibody landscapes against a large panel of H3N2 influenza viruses showed distinct age effects whereby subjects over 40years old had a bimodal baseline HI distribution pattern, with the highest HI titers against the very oldest H3N2 isolates and with a second HI peak against influenza isolates from the last 5-10years. By contrast, subjects >40years had a unimodal baseline HI distribution with peak recognition of H3N2 isolates from approximately 20years ago. The reduced dose TIV vaccine containing Advax adjuvant was well tolerated and no safety issues were identified. Hence, delta inulin may be a useful adjuvant for use in seasonal or pandemic influenza vaccines. Australia New Zealand Clinical Trial Registry: ACTRN12607000599471., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Background: Antigenic characterization of influenza viruses is typically based on hemagglutination inhibition (HI) assay data for viral isolates tested against strain-specific postinfection ferret antisera. Here, similar virus characterizations were performed using serological data from humans with primary influenza A(H3N2) infection., Methods: We screened sera collected between 1995 and 2011 from children between 9 and 24 months of age for influenza virus antibodies, performed HI tests for the positive sera against 23 influenza viruses isolated between 1989 and 2011, and measured HI titers of antisera against influenza A(H3N2) from 24 ferrets against the same panel of viruses., Results: Of the 17 positive human sera, 6 had a high response, showing HI patterns that would be expected from primary infection antisera, while 11 sera had lower, more dispersed patterns of reactivity that are not easily explained. The antigenic map based on the high-response human HI data was similar to the map created using ferret data., Conclusions: Although the overall structure of the ferret and human antigenic maps is similar, local differences in virus positions indicate that the human and ferret immune system might see antigenic properties of viruses differently. Further studies are needed to establish the degree of similarity between serological patterns in ferret and human data., (© The Author 2015. Published by Oxford University Press for the Infectious Diseases Society of America.)

We introduce the antibody landscape, a method for the quantitative analysis of antibody-mediated immunity to antigenically variable pathogens, achieved by accounting for antigenic variation among pathogen strains. We generated antibody landscapes to study immune profiles covering 43 years of influenza A/H3N2 virus evolution for 69 individuals monitored for infection over 6 years and for 225 individuals pre- and postvaccination. Upon infection and vaccination, titers increased broadly, including previously encountered viruses far beyond the extent of cross-reactivity observed after a primary infection. We explored implications for vaccination and found that the use of an antigenically advanced virus had the dual benefit of inducing antibodies against both advanced and previous antigenic clusters. These results indicate that preemptive vaccine updates may improve influenza vaccine efficacy in previously exposed individuals., (Copyright © 2014, American Association for the Advancement of Science.)