Mpox-specific immune responses elicited by vaccination or infection in people living with HIV.

In the recent mpox outbreak, people living with HIV (PLWH) were at high risk both for contracting infection and for suffering a more severe disease course. We studied cellular and humoral immune responses elicited by mpox infection (n = 5; n = 3 PLWH) or smallpox vaccination (n = 17; all PLWH) in a cohort of men who have sex with men. All PLWH were successfully treated, with stable CD4 counts and undetectable HIV viral loads. 11/17 vaccinated individuals had received childhood smallpox vaccination. In this group of individuals, both two-dose MVA-vaccination and natural infection evoked mpox-specific immune responses mediated by B cells as well as CD4 and CD8 T cells. This study improves our understanding of smallpox vaccination mediated cross-reactivity to other orthopox viruses, and the long-lasting durability of childhood smallpox vaccination mediated immune responses including in PLWH.

Persistent immune abnormalities discriminate post-COVID syndrome from convalescence.

BACKGROUND: Innate lymphoid cells (ILCs) are key organizers of tissue immune responses and regulate tissue development, repair, and pathology. Persistent clinical sequelae beyond 12 weeks following acute COVID-19 disease, named post-COVID syndrome (PCS), are increasingly recognized in convalescent individuals. ILCs have been associated with the severity of COVID-19 symptoms but their role in the development of PCS remains poorly defined. METHODS AND RESULTS: Here, we used multiparametric immune phenotyping, finding expanded circulating ILC precursors (ILCPs) and concurrent decreased group 2 innate lymphoid cells (ILC2s) in PCS patients compared to well-matched convalescent control groups at > 3 months after infection or healthy controls. Patients with PCS showed elevated expression of chemokines and cytokines associated with trafficking of immune cells (CCL19/MIP-3b, FLT3-ligand), endothelial inflammation and repair (CXCL1, EGF, RANTES, IL-1RA, PDGF-AA). CONCLUSION: These results define immunological parameters associated with PCS and might help find biomarkers and disease-relevant therapeutic strategies.

Characterization of SARS-CoV-2 Escape Mutants to a Pair of Neutralizing Antibodies Targeting the RBD and the NTD.

Mutations in the spike protein of SARS-CoV-2 can lead to evasion from neutralizing antibodies and affect the efficacy of passive and active immunization strategies. Immunization of mice harboring an entire set of human immunoglobulin variable region gene segments allowed to identify nine neutralizing monoclonal antibodies, which either belong to a cluster of clonally related RBD or NTD binding antibodies. To better understand the genetic barrier to emergence of SARS-CoV-2 variants resistant to these antibodies, escape mutants were selected in cell culture to one antibody from each cluster and a combination of the two antibodies. Three independently derived escape mutants to the RBD antibody harbored mutations in the RBD at the position T478 or S477. These mutations impaired the binding of the RBD antibodies to the spike protein and conferred resistance in a pseudotype neutralization assay. Although the binding of the NTD cluster antibodies were not affected by the RBD mutations, the RBD mutations also reduced the neutralization efficacy of the NTD cluster antibodies. The mutations found in the escape variants to the NTD antibody conferred resistance to the NTD, but not to the RBD cluster antibodies. A variant resistant to both antibodies was more difficult to select and only emerged after longer passages and higher inoculation volumes. VOC carrying the same mutations as the ones identified in the escape variants were also resistant to neutralization. This study further underlines the rapid emergence of escape mutants to neutralizing monoclonal antibodies in cell culture and indicates the need for thorough investigation of escape mutations to select the most potent combination of monoclonal antibodies for clinical use.

A pair of noncompeting neutralizing human monoclonal antibodies protecting from disease in a SARS-CoV-2 infection model.

TRIANNI mice carry an entire set of human immunoglobulin V region gene segments and are a powerful tool to rapidly isolate human monoclonal antibodies. After immunizing these mice with DNA encoding the spike protein of SARS-CoV-2 and boosting with spike protein, we identified 29 hybridoma antibodies that reacted with the SARS-CoV-2 spike protein. Nine antibodies neutralize SARS-CoV-2 infection at IC50 values in the subnanomolar range. ELISA-binding studies and DNA sequence analyses revealed one cluster of three clonally related neutralizing antibodies that target the receptor-binding domain and compete with the cellular receptor hACE2. A second cluster of six clonally related neutralizing antibodies bind to the N-terminal domain of the spike protein without competing with the binding of hACE2 or cluster 1 antibodies. SARS-CoV-2 mutants selected for resistance to an antibody from one cluster are still neutralized by an antibody from the other cluster. Antibodies from both clusters markedly reduced viral spread in mice transgenic for human ACE2 and protected the animals from SARS-CoV-2-induced weight loss. The two clusters of potent noncompeting SARS-CoV-2 neutralizing antibodies provide potential candidates for therapy and prophylaxis of COVID-19. The study further supports transgenic animals with a human immunoglobulin gene repertoire as a powerful platform in pandemic preparedness initiatives.

Association of Plasma Aß40 Peptides, But Not Aß42, with Coronary Artery Disease and Diabetes Mellitus.

BACKGROUND/OBJECTIVE: Plasma levels of amyloid-beta (Aß) 1-40 peptide have been proposed to be associated with cardiovascular mortality in patients with coronary artery disease (CAD). Therefore, we aimed to investigate the association of plasma Aß levels with CAD, cardiovascular risk factors (CVRF), and APOE genotype in non-demented elderly individuals. METHODS: Plasma Aß1 - 40 and Aß1 - 42 levels of 526 individuals (mean age of 63.0±7.3 years) were quantified with the INNO-BIA plasma Aß forms assay based on multiplextrademark technique. APOE genotype was determined with an established protocol. Presence of CAD and CVRFs were ascertained using a questionnaire and/or medical records. RESULTS: Plasma Aß1 - 40 levels were significantly higher in individuals with CAD (p = 0.043) and, independently, in individuals with diabetes mellitus (DM) type 2 (p = 0.001) while accounting for age- and gender-effects. Plasma Aß1 - 42 levels were higher in APOEɛ4 carriers (p = 0.004), but were neither relevantly associated with CAD nor with any CVRF. Plasma Aß1 - 40 showed no association with APOE genotype. DISCUSSION: Our findings argue for an association of circulating plasma Aß1 - 40 peptides with incident CAD and DM. Further investigations are needed to entangle the role of Aß1 - 40 role in the pathophysiology of cardiovascular disease independent of its known role in Alzheimer's disease.

Risk-inducing activities leading to injuries in a child and adolescent population of Germany.

BACKGROUND: Injuries are the most common cause of mortality in children, also accounting considerably for childhood morbidity. However, data on injuries only provide valid information on the actual risk of each injury-causing activity when taken in consideration of the relationship with actual activity exposure data. Therefore, the primary goal of this investigation is to determine the relative risk of normal child and adolescent activities. METHODS: From January 1, 1999 to December 31, 2001, a school questioning in regard to social, pedagogic, and leisure activities was performed among 2,325 students ranging from 6 to 17 years old. A total of 3,645 injuries sustained by children and adolescents treated at the surgical emergency department of the University Hospital Dresden were analyzed. Furthermore, a danger awareness test was performed. RESULTS: Forty-three percent of all injuries happened during leisure time, 41% at school, 8% in traffic, and 8% at home. Bicycle riding was pointed out as the most frequent leisure activity, regardless of gender and age. Horse riding had a 9-fold increased risk and moped driving had a 23.75-fold increased risk for injury compared with adolescent bike riding. Horse riding and snowboarding showed an increased risk for injury in children (5.6- and 4.2-fold, relative to biking). The level of danger awareness was significantly lower in children with a history of frequent injuries. CONCLUSIONS: The riskier activities were horse-riding, moped driving, and snowboarding. The level of danger awareness did affect the frequency of injuries. The authors recommend a danger awareness test for all children to identify those who would benefit from injury prevention training.