Severe COVID-19 appears rare in children. This is unexpected, especially in young infants, who are vulnerable to severe disease caused by other respiratory viruses. We evaluate convalescent immune responses in four infants under 3 months old with confirmed COVID-19 who presented with mild febrile illness, alongside their parents, and adult controls recovered from confirmed COVID-19. Although not statistically significant, compared to seropositive adults, infants have high serum levels of IgG and IgA to SARS-CoV-2 spike protein with corresponding functional ability to block SARS-CoV-2 cellular entry. Infants also exhibit robust saliva anti-spike IgG and IgA responses. Spike-specific IFN-γ production by infant peripheral blood mononuclear cells appears restrained, but the frequency of spike-specific IFN-γ and/or TNF-ɑ producing T cells is comparable between infants and adults. On principal component analysis, infant immune responses appear distinct from their parents. Robust functional antibody responses alongside restrained IFN-γ production may help protect infants from severe COVID-19.

COVID-19 continues to damage populations, communities and economies worldwide. Vaccines have reduced COVID-19-related hospitalisations and deaths, primarily in developed countries. Persisting infection rates, and highly transmissible SARS-CoV-2 Variants of Concern (VOCs) causing repeat and breakthrough infections, underscore the ongoing need for new treatments to achieve a global solution. Based on ADDomer, a self-assembling protein nanoparticle scaffold, we created ADDoCoV, a thermostable COVID-19 candidate vaccine displaying multiple copies of a SARS-CoV-2 receptor binding motif (RBM)-derived epitope. In vitro generated neutralising nanobodies combined with molecular dynamics (MD) simulations and electron cryo-microscopy (cryo-EM) established authenticity and accessibility of the epitopes displayed. A Gigabody comprising multimerized nanobodies prevented SARS-CoV-2 virion attachment with picomolar EC50. Antibodies generated by immunising mice cross-reacted with VOCs including Delta and Omicron. Our study elucidates nasal administration of ADDomer-based nanoparticles for active and passive immunisation against SARS-CoV-2 and provides a blueprint for designing nanoparticle reagents to combat respiratory viral infections.

COVID-19 causes immune perturbations which may persist long-term, and patients frequently report ongoing symptoms for months after recovery. We assessed immune activation at 3-12 months post hospital admission in 187 samples from 63 patients with mild, moderate or severe disease and investigated whether it associates with long COVID. At 3 months, patients with severe disease displayed persistent activation of CD4+ and CD8+ T-cells, based on expression of HLA-DR, CD38, Ki67 and granzyme B, and elevated plasma levels of IL-4, IL-7, IL-17 and TNF-α compared to mild and/or moderate patients. Plasma from severe patients at 3 months caused T-cells from healthy donors to upregulate IL-15Rα, suggesting that plasma factors in severe patients may increase T-cell responsiveness to IL-15-driven bystander activation. Patients with severe disease reported a higher number of long COVID symptoms which did not however, correlate with cellular immune activation/pro-inflammatory cytokines after adjusting for age, sex and disease severity. Our data suggests that long COVID and persistent immune activation may correlate independently with severe disease.

Objectives To determine whether artificial urethral sphincter filling volume is proportional to peak pressure exerted on the urethra. Materials and Methods Urethral pressure profilometry was performed in five female, medium‐sized, mixed‐breed canine cadavers following artificial urethral sphincter placement. Maximum urethral pressure was recorded following sequential incremental inflation of 0.15 mL and compared to baseline pressure and between dogs using two‐way analysis of variance. Results Artificial urethral sphincter placement in cadavers was associated with an increase in urethral pressure, which was significantly correlated with inflation volume. The correlation was non‐linear and demonstrated considerable individual variation. Maximum urethral pressures after artificial urethral sphincter placement exceeded those reported in conscious continent dogs within a narrow volume range, in which a 0.15 mL infusion more than doubled maximal urethral pressures. Clinical Significance Rapid increases in urethral pressure from the artificial urethral sphincter over a small range of filling volumes (0.15 mL increments) might explain why some clinical cases can become suddenly dysuric following incremental inflations. We suggest that smaller increments of filling (0.05 to 0.1 mL) may achieve finer pressure control.

COVID-19 causes immune perturbations which may persist long-term, and patients frequently report ongoing symptoms for months after recovery. We assessed the extent and nature of immune activation at 3 months post hospital admission in patients with mild, moderate or severe COVID-19 and investigated whether immune activation associates with disease severity and long COVID. Patients with severe disease displayed persistent activation of CD4+ and CD8+ T-cells, based on expression of HLA-DR, CD38, Ki67 and granzyme B, but they lacked activation of other immune subsets. Elevated plasma levels of IL-4, IL-7, IL- 17 and TNF-α were present in patients with severe compared to mild and/or moderate disease. Plasma from severe patients caused T-cells from healthy donors to upregulate IL-15Rα, suggesting that factors in the plasma of severe patients may increase T-cell responsiveness to IL-15-driven ‘bystander” activation, which may drive persistent T-cell activation after severe COVID-19. Patients with severe disease reported a higher number of long COVID symptoms which correlated with the frequency of two subsets of activated CD4+ and CD8+ T cells (CD4+ T-cell population 2 and CD8+ T-cell population 4; FDR p<0.05), however these associations were lost after adjusting for age, sex and disease severity. Our data suggests that persistent immune activation and long COVID correlate independently with severe disease.

Tumors generate an immune-suppressive environment that prevents effective killing of tumor cells by CD8+ cytotoxic T cells (CTL). It remains largely unclear upon which cell type and at which stage of the anti-tumor response mediators of suppression act. We have combined an in vivo tumor model with a matching in vitro reconstruction of the tumor microenvironment based on tumor spheroids to identify suppressors of anti-tumor immunity that directly act on interaction between CTL and tumor cells and to determine mechanisms of action. An adenosine 2A receptor antagonist, as enhanced by blockade of TIM3, slowed tumor growth in vivo. Engagement of the adenosine 2A receptor and TIM3 reduced tumor cell killing in spheroids, impaired CTL cytoskeletal polarization ex vivo and in vitro and inhibited CTL infiltration into tumors and spheroids. With this role in CTL killing, blocking A2AR and TIM3 may complement therapies that enhance T cell priming, e.g. anti-PD-1 and anti-CTLA-4.

Tumors generate an immune-suppressive environment that prevents effective killing of tumor cells by CD8+ cytotoxic T cells (CTL). It remains largely unclear upon which cell type and at which stage of the anti-tumor response mediators of suppression act. We have combined an in vivo tumor model with a matching in vitro reconstruction of the tumor microenvironment based on tumor spheroids to identify suppressors of anti-tumor immunity that directly act on interaction between CTL and tumor cells and to determine mechanisms of action. An adenosine 2a receptor antagonist, as enhanced by blockade of TIM3, slowed tumor growth in vivo. Engagement of the adenosine 2a receptor and TIM3 reduced tumor cell killing in spheroids, impaired CTL cytoskeletal polarization ex vivo and in vitro and inhibited CTL infiltration into tumors and spheroids. With this focus on CTL killing, blocking A2aR and TIM3 complements therapies that enhance T cell priming, e.g. anti-PD1 and anti-CTLA-4.

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