IrsiCaixa

TARDBP (TDP-43), a multifunctional RNA-binding protein, has emerged as a critical host factor controlling HIV-1 replication by destabilizing the viral Pr55Gag polyprotein, precursor to capsid (CA), matrix, and nucleocapsid. TARDBP promotes HDAC6-mediated autophagic degradation of HIV-1 Pr55Gag and Vif, impairing nascent virion assembly and infectivity. Simultaneously, TARDBP disrupts viral entry by modulating HDAC6-dependent microtubule (MT) deacetylation, blocking the viral core at the pore fusion step in target cells. These dual mechanisms position TARDBP as a central antiviral defender, paralleling the CA- and viral core-targeting activity of nonhuman TRIM5α and novel therapeutic inhibitors such as lenacapavir. This review synthesizes evidence for TARDBP’s roles in HIV-1 restriction, highlighting its potential to destabilize the CA-formed viral core during both viral assembly and entry. We propose that enhancing TARDBP activity, combined with destabilizing CA-binding drugs, could offer a synergistic strategy to combat drug-resistant HIV-1 strains and target viral reservoirs, providing hope for functional cure approaches. TARDBP (TDP-43) is a protein that normally helps cells manage RNA, but recent studies have shown that TARDBP also plays a surprisingly powerful role in fighting HIV-1. This protein weakens the virus in two main ways. First, TARDBP regulates and works with another protein called HDAC6 to break down important viral components (particularly HIV-1 Pr55Gag and Vif) through the cell’s natural recycling system, known as autophagy. Since Pr55Gag is needed to construct the viral core that contains and protects the viral genome, as well as the matrix and nucleocapsid, destroying it prevents new virus particles from forming correctly or becoming infectious. Second, TARDBP hinders HIV-1´s ability to enter cells. It does this by affecting the microtubules inside the cells, which are similar to tiny tracks that the virus uses to reach the nucleus. By modulating the effect of HDAC6 on microtubules, TARDBP prevents HIV-1 from completing the fusion step needed to release its viral core (capsid) and genome into the host cell. Together, these two actions make TARDBP a strong natural defender against HIV-1 by avoiding CA (viral core) formation and/or viral core entry into the cells. Its behaviour is complementary and in phase to that of other antiviral factors, such as nonhuman TRIM5α, as well as to that of new drugs that target the CA (viral core), such as lenacapavir. Researchers propose that boosting TARDBP activity, especially alongside capsid-targeting drugs, could offer a dual strategy: combating drug-resistant HIV-1 and helping to reduce the viral reservoir.

The biological mechanisms underlying long COVID in the pediatric population are poorly understood. Our study aimed to characterize the immune pathophysiology of long COVID in children and young people (CYP). We analyzed major immune cell compartments in PBMCs, as well as specific SARS-CoV-2 antibody response in CYP with (n=99) and without (n=18) long COVID at three months following acute infection. Our findings indicate that pediatric long COVID is associated with a dysregulated immune response characterized by altered innate immunity and overactivated T-, B- and NK-cell responses. Furthermore, CYP with long COVID had an impaired humoral response to SARS-CoV-2 marked by a dysregulated B-cell compartment and lower levels of anti-RBD IgG and IgA. This correlated with reduced neutralizing capacity against SARS-CoV-2. Random forest analysis identified CCR6 expression on myeloid cells as the most relevant biomarker that distinguishes long COVID from control individuals with 79% accuracy.

The rapid evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has compromised the efficacy of many authorized monoclonal antibody products. This highlights the need for alternative strategies, especially for vulnerable populations such as immunocompromised individuals. Here, we optimized angiotensin-converting enzyme 2 (ACE2)-Fc fusion proteins by combining three engineering steps: in silico mutagenesis of the S protein binding interface to increase affinity, insertion of a flexible linker to improve protein stability and S protein accessibility, and generation of a tetrameric molecule to maximize avidity. Neutralizing activity was tested against a large panel of pre-Omicron and Omicron pseudoviruses and authentic viruses, including JN.1 and KP.2 variants. Optimized ACE2-Fc molecules demonstrated potent neutralizing activity, in the picomolar range, against all SARS-CoV-2 variants. Our molecules displayed similar potency but better resilience when compared to the monoclonal antibody Sipavibart. These findings support ACE2-Fc proteins as robust candidates for next-generation interventions against infection by an evolving SARS-CoV-2.

Multisystem Inflammatory Syndrome in Children (MIS-C) is a severe post-COVID-19 complication characterized by hyperimmune activation and systemic inflammation. Identifying biomarkers for disease severity and predicting ICU admission is critical. This study analyzed 92 inflammatory biomarkers in serum samples from 22 pediatric MIS-C patients and 17 convalescent COVID-19 children using Olink proteomics. MIS-C samples were taken at diagnosis, before treatment, and at follow-up. Convalescent COVID-19 samples were taken 3 to 5 weeks after acute COVID-19 diagnosis, at a similar time to MIS-C theoretical occurrence. The study identified 29 significantly altered biomarkers in MIS-C, including elevated pro-inflammatory cytokines (IFN-γ, IL-6, TNF, IL-18), chemokines (CXCL9, CXCL10, CXCL11), and immune regulators (IL-10, PD-L1, CDCP1). Among these, random forest analysis highlighted 18 key markers distinguishing MIS-C from convalescent cases. ICU-admitted MIS-C patients displayed distinct biomarker signatures, and the differential regulation of IL-2, IL-33, CD244, SCF, TNFRSF9, and CD8α, was sufficient to predict almost all ICU admissions. Notably, lower levels of soluble CD244 and TNFRSF9 correlated with longer hospital stays. Finally, longitudinal analysis showed biomarker normalization within two months post-MIS-C. This study provides a detailed characterization of the MIS-C inflammatory response, identifying potential biomarkers for improved early diagnosis and clinical management. MIS-C incidence has substantially decreased since the beginning of the COVID-19 pandemic, but rare cases are still occurring with severe to critical presentation. We identified 6 biomarkers, IL-2, IL-33, CD244, SCF, TNFRSF9, and CD8α, predictors of ICU-admission in MIS-C. We showed the normalization of cytokine profiles by 2 months following treatment in MIS-C. This study Identified potential biomarkers for improved early diagnosis and clinical management of MIS-C.

Abstract Objectives Although rare, severe complications may follow SARS-CoV-2 infection in pediatric populations. PHH-1V, a protein-based, bivalent, adjuvanted COVID-19 vaccine, demonstrated strong immunogenicity and favorable safety as a booster in adults. This study further evaluated PHH-1V as a heterologous booster in pediatric adolescent population. Study design HIPRA-HH-3 was a phase IIb, open-label, multicenter, non-inferiority trial assessing the immunogenicity and safety of PHH-1V in 240 healthy adolescents (≥ 12 to < 18 years) previously vaccinated with BNT162b2. Immunogenicity (N = 88) was evaluated by measuring neutralizing antibodies against SARS-CoV-2 variants, total binding antibodies, and T-cell responses at day 14 post-booster, compared to young adults (≥ 18 to ≤ 25 years) (N = 81) from the previous HIPRA-HH-2 study, who had also received the PHH-1V booster vaccine. Safety endpoints included all adverse events through day 28. Results Neutralizing titers against Omicron BA.1 (primary endpoint), WH1, Beta, and Delta variants and total binding antibodies were significantly higher in adolescents than in young adults (p < 0.001), demonstrating non-inferiority (margin < 1.5). T-cell responses against Omicron BA.1 and Beta variants also increased significantly (p < 0.001). Adverse events were mostly mild or moderate, primarily injection-site pain and headache. No serious adverse events were reported. Conclusions PHH-1V is safe and immunogenic as a heterologous booster in adolescents, inducing both humoral and cellular responses with SARS-CoV-2 cross-variant immune recognition. These findings support the use of PHH-1V in adolescent vaccination strategies. Additional data on long-term protection in this population, including specific risk groups, remain needed. Clinical Trial Registration NCT06234956 ( https://clinicaltrials.gov/study/NCT06234956 ) and 2023-504639-42-00 ( https://euclinicaltrials.eu/search-for-clinical-trials/?lang=en&EUCT=2023-504639-42-00 ).

Enfuvirtide, the first HIV fusion inhibitor, exhibits remarkable antiviral efficacy and a favourable safety profile compared with antiretroviral therapy alone. However, its clinical application is constrained by the necessity for subcutaneous administration and the high incidence of injection site reactions (ISRs) in 98% of patients. This study seeks to overcome these limitations by developing dissolving microneedle array patches (DMAPs), offering a painless and efficient alternative for enfuvirtide delivery. Two bilayer DMAP designs featuring poly(vinyl pyrrolidone) (PVP) based-hydrophilic and poly(lactic acid) (PLA)-based hydrophobic baseplates were engineered, incorporating a novel PLA-silica baseplate as a colorimetric dissolution indicator for visual feedback on successful patch insertion and timely removal. The DMAPs with embedded indicators exhibited a rapid color change from yellow to green within 3min of insertion into the rats' dorsal skin. This change was triggered by hydration of the dye crystal violet encapsulated in silica, as interstitial fluid migrated from the needle shafts to the baseplate. A subsequent transition to purple occurred within 2h due to further dye hydration, indicating complete needle dissolution and successful delivery of enfuvirtide. In vivo studies on Sprague Dawley rats demonstrated that enfuvirtide achieved a Cmax of 1864±480ng/mL at 0.5h with the PLA-silica DMAP, compared to 973±200ng/mL at 1h with the PVP-baseplate DMAP. Both formulations exhibited biocompatibility and safety in vivo, with the PLA-silica DMAP supporting rapid drug release suitable for short-term applications, while the PVP-based DMAP offered potential for long-term use without irritation. These findings underscore DMAPs as a promising alternative to subcutaneous injection of enfuvirtide, capable of reducing ISRs and potentially enhancing patient adherence. Notably, this work introduced an innovative solution for prompt patch removal upon complete drug delivery, effectively addressing dosing inconsistencies and enabling individualised administration, which is crucial for ensuring the reliability and patient acceptability for widespread adoption of this technology.

BackgroundThe ongoing evolution of SARS-CoV-2, particularly through the emergence of new variants, continues to challenge our understanding of immune protection. While antibody levels correlate with protection against earlier variants such as Alpha and Delta, their relationship with Omicron sub-variants remains unclear.MethodsTo investigate the role of antibody levels and neutralizing activity in preventing breakthrough infections, we analyzed longitudinal SARS-CoV-2 humoral responses and neutralizing activity against the ancestral virus and major emerging variants in a well-characterized cohort of healthcare workers in Spain (N = 405).ResultsWe find that antibody levels and neutralization titers are key indicators of protection against SARS-CoV-2, including the more evasive BQ.1 and XBB Omicron variants. Higher IgG and IgA levels are associated with protection over three 6-month follow-up periods sequentially dominated by BA.1, BA.2, BA.5, BQ.1, and XBB Omicron sub-variants, although the strength of the association between antibody levels and protection declines over time.ConclusionsOur findings demonstrate that binding antibody levels and neutralizing responses are valid correlates of protection against more evasive BQ.1 and XBB Omicron variants, although the strength of this association diminishes over time. Additionally, our results underscore the importance of continuous monitoring and updating vaccination strategies to maintain effective protection against emerging SARS-CoV-2 variants.

Natural Killer (NK) cells are promising candidates for targeting persistently infected CD4 + T cells in people with HIV-1 (PWH). However, chronicity of HIV-1 infection impairs NK cell functionality, requiring additional strategies to potentiate their cytotoxic activity. This study demonstrates that dendritic cells primed with nanoparticles containing Poly I:C (Nano-PIC-MDDC) enhance the natural cytotoxic function of NK cells from effective responder PWH. These NK cells exhibit increased proportions of NKG2C+ cell subsets capable of eliminating HIV-1 infected CD4 + T cells through the TRAIL receptor. In contrast, in non-responder PWH, elevated expression of the inhibitory receptor TIGIT is associated with reduced frequencies of NKG2C + NK cells and diminished TRAIL expression. TIGIT blockade restores cytotoxicity of NK cells from non-responder PWH against HIV-1-infected cells by upregulating TRAIL. Furthermore, combining Nano-PIC-MDDC-primed NK cells with anti-TIGIT immunotherapy in humanized NSG mice reduces the expansion of HIV-1 infected cells, preserves NKG2C + NK cell precursors and increases TRAIL expression in tissue. Collectively, these findings support the combined use of Nano-PIC-MDDC and TIGIT blockade as a promising immunotherapeutic strategy toward an HIV-1 cure.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the coronavirus disease 19 (COVID-19) pandemic, significantly impacting global health, economies, and social stability. In February 2020, the first cases of SARS-CoV-2 infections in animals were documented, highlighting the potential risks posed by regular human-animal interactions in facilitating viral transmission. In consequence, it is essential to validate surveillance methods for SARS-CoV-2 in animals. In the present study, 101 sera from different animal species (36 cats, 41 dogs, 4 ferrets, 10 wild boar, 6 domestic goats, and 4 lions) were tested using three different ELISA kits to evaluate humoral responses against SARS-CoV-2. ELISA results were compared and correlated with a pseudovirus neutralization test (pVNT), considered as the reference assay. ELISA-1, targeting the receptor binding domain (RBD) neutralizing antibodies (nAbs) of SARS-CoV-2, exhibited the highest diagnostic performance, and proved to be a reliable tool for initial screenings in high-throughput animal studies. In contrast, ELISA-2 (also targeting RBD nAbs) and ELISA-3 (targeting nucleoprotein antibodies) demonstrated lower sensitivity for detecting seropositive animals.