Relationship between TIGIT expression on T cells and the prognosis of patients with hepatocellular carcinoma.

BACKGROUND: Transcatheter arterial chemoembolization (TACE) combined with targeted therapy and immunotherapy can significantly improve the prognosis of patients with hepatocellular carcinoma (HCC). T-cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif domains (TIGIT) is a novel immunosuppressive molecule. This study aimed to analyze the clinical correlation between TIGIT expression on T cells and patients with HCC. METHODS: Clinical data from 140 patients with HCC were retrospectively collected, and TIGIT expression on T cells was examined in each patient. Patients were subsequently divided into high- and low-expression groups, and their prognosis was analyzed. RESULTS: Patients with a high TIGIT expression on their T cells at baseline had a larger tumor volume, later staging, higher proportion of regulatory T cells, higher blood concentrations of interleukin (IL)-6 and IL-10, and lower interferon-γ concentrations. Following TACE, CD155 concentration decreased; however, TACE did not affect TIGIT expression on T cells. Additionally, among patients receiving TACE combined with apatinib and camrelizumab treatment, patients with a high TIGIT expression on T cells had significantly shorter progression-free survival (PFS) and overall survival times than those of patients in the low-expression group. Patients receiving TACE combined with apatinib and camrelizumab treatment with higher TIGIT expression have shorter PFS time than those receiving TACE combined with apatinib treatment. CONCLUSIONS: Patients with HCC that have a high TIGIT expression on their T cells exhibited poorer baseline characteristics, immunosuppressive status, and prognosis after receiving TACE combined with apatinib and camrelizumab and maybe more suited to receive TACE combined with apatinib treatment instead.

The Functions of SARS-CoV-2 Receptors in Diabetes-Related Severe COVID-19.

Angiotensin-converting enzyme 2 (ACE2) is considered a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) receptor of high importance, but due to its non-ubiquitous expression, studies of other proteins that may participate in virus internalisation have been undertaken. To date, many alternative receptors have been discovered. Their functioning may provide an explanation for some of the events observed in severe COVID-19 that cannot be directly explained by the model in which ACE2 constitutes the central point of infection. Diabetes mellitus type 2 (T2D) can induce severe COVID-19 development. Although many mechanisms associated with ACE2 can lead to increased SARS-CoV-2 virulence in diabetes, proteins such as basigin (CD147), glucose-regulated protein 78 kDa (GRP78), cluster of differentiation 4 (CD4), transferrin receptor (TfR), integrins α5ß1/αvß3, or ACE2 co-receptors neuropilin 2 (NRP2), vimentin, and even syalilated gangliosides may also be responsible for worsening the COVID-19 course. On the other hand, some others may play protective roles. Understanding how diabetes-associated mechanisms can induce severe COVID-19 via modification of virus receptor functioning needs further extensive studies.

Prognostic impact of nectin-like molecule-5 (CD155) expression in non-small cell lung cancer.

BACKGROUND: CD155 is a transmembrane protein that inhibits antitumor immune response and represents a predictor of worse prognosis in non-small-cell lung cancer (NSCLC). However, it remains unexplored its association with clinical characteristics and genomic status of Latin American patients. This study characterizes the CD155 expression and its clinical implications in this population. METHODS: Tissue biopsies from 86 patients with locally-advanced or metastatic NSCLC were assessed for CD155 protein expression, ALK rearrangements and EGFR mutations. Cutoff values for high CD155 expression (CD155high) were determined from receiver operating characteristic (ROC) curves according to 2-year survival. It was evaluated its association with clinicopathological features, median progression-free survival (mPFS) and overall survival (mOS). RESULTS: the cutoff score for CD155high was 155 in the entire cohort and in patients without oncogenic alterations, and it was 110 in patients with oncogenic alterations. Eighty-four patients (97.7%) were CD155 positive, of which fifty-six (65.0%) had CD155high. EGFR L858R mutation related to lower CD155 IHC score than exon 19 deletion. Individuals with CD155high showed a shorter mOS (13.0 vs. 30.8 months; HR: 1.96 [95% CI, 1.15-3.35]; p = 0.014). Patients without oncogenic alterations having a CD155high displayed shorter mPFS (1.6 vs. 6.4 months, HR: 2.09 [95% CI, 1.06-4.20]; p = 0.034) and mOS (2.9 vs. 23.1 months; HR: 1.27 [95% CI, 1.07- 4.42]; p = 0.032). Patients with oncogenic alterations having CD155high only showed a trend to shorter mOS (26.3 vs. 52.0 months; HR: 2.39 [95% CI, 0.98-5.83]; p = 0.058). CONCLUSION: CD155high is a predictor of worse outcomes in patients with advanced NSCLC, predominantly among those without oncogenic alterations. CD155 could be a potential biomarker and a molecular target in patients with poor responses to current therapies.

The receptor VLDLR binds Eastern Equine Encephalitis virus through multiple distinct modes.

Eastern Equine Encephalitis virus (EEEV) is an alphavirus that can cause severe diseases in infected humans. The very low-density lipoprotein receptor (VLDLR) was recently identified as a receptor of EEEV. Herein, we performed cryo-electron microscopy structural and biochemistry studies on the specific interactions between EEEV and VLDLR. Our results show that VLDLR binds EEEV at three different sites A, B and C through its membrane-distal LDLR class A (LA) repeats. Site A is located in the cleft in between the E1-E2 heterodimers. Site B is located near the connecting ß ribbon of E2 and is in proximity to site A, while site C is on the domain B of E2. The binding of VLDLR LAs to EEEV is in complex modes, including the LA1-2 and LA3-5 mediated two major modes. Disruption of the LA1-2 mediated binding significantly affect the cell attachment of EEEV. However, the mutation W132G of VLDLR impairs the binding of LA3, drives the switch of the binding modes, and significantly enhances the attachment of EEEV to the cell. The W132G variant of VLDLR could be identified in human genome and SNP sequences, implying that people with similar mutations in VLDLR may be highly susceptible to EEEV infection.

The Nectin family ligands, PVRL2 and PVR, in cancer immunology and immunotherapy.

In recent years, immunotherapy has emerged as a crucial component of cancer treatment. However, its efficacy remains limited across various cancer types, highlighting unmet needs. Poliovirus receptor-related 2 (PVRL2) and Poliovirus receptor (PVR) are members of the Nectin and Nectin-like Molecules family, known for their role as cell-cell adhesion molecules. With the development of immunotherapy, their involvement in tumor immune mechanisms as immune checkpoint factors has garnered significant attention. PVRL2 and PVR are predominantly expressed on tumor cells and antigen-presenting cells, binding to PVRIG and TIGIT, respectively, which are primarily found on T and NK cells, thereby suppressing antitumor immunity. Notably, gynecological cancers such as ovarian and endometrial cancers exhibit high expression levels of PVRL2 and PVR, with similar trends observed in various other solid and hematologic tumors. Targeting these immune checkpoint pathways offers a promising therapeutic avenue, potentially in combination with existing treatments. However, the immunomodulatory mechanism involving these bindings, known as the DNAM-1 axis, is complex, underscoring the importance of understanding it for developing novel therapies. This article comprehensively reviews the immunomodulatory mechanisms centered on PVRL2 and PVR, elucidating their implications for various cancer types.

Interaction of Receptor-Binding Domain of the SARS-CoV-2 Omicron Variant with hACE2 and Actin.

The omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified in 2021 as a variant with heavy amino acid mutations in the spike protein, which is targeted by most vaccines, compared to previous variants. Amino acid substitutions in the spike proteins may alter their affinity for host viral receptors and the host interactome. Here, we found that the receptor-binding domain (RBD) of the omicron variant of SARS-CoV-2 exhibited an increased affinity for human angiotensin-converting enzyme 2, a viral cell receptor, compared to the prototype RBD. Moreover, we identified ß- and γ-actin as omicron-specific binding partners of RBD. Protein complex predictions revealed that many omicron-specific amino acid substitutions affected the affinity between RBD of the omicron variant and actin. Our findings indicate that proteins localized to different cellular compartments exhibit strong binding to the omicron RBD.

Aspirin Inhibits Colorectal Cancer via the TIGIT-BCL2-BAX pathway in T Cells.

The T cell immunoglobulin and ITAM domain (TIGIT) is a recently discovered synergistic co-suppressor molecule that plays an important role in immune response and tumor immune escape in the context of cancer. Importantly, CD155 acts as a receptor for TIGIT, and CD155 signaling to immune cells is mediated through interactions with the co-stimulatory immune receptor CD226 (DNAM-1) and the inhibitory checkpoint receptors TIGIT and CD96. Aspirin (ASA) has been shown to reduce the growth and survival of colorectal cancer (CRC) cells, but the immunological mechanisms involved have not been sufficiently elucidated. In the present study the effects of aspirin on CRC in mice and on Jurkat cells were investigated. Aspirin may suppress the expression of TIGIT on T cells and Regulatory T cells (Tregs) and inhibit T cell viability, and therefore induce tumor cell apoptosis. TIGIT is expressed at higher levels on infiltrating lymphocytes within CRC tumor tissue than adjacent. Further, aspirin could inhibit Jurkat cell proliferation and induce apoptosis via downregulation of TIGIT expression and the anti-apoptosis B cell lymphoma 2 (BCL2) protein and upregulation of BCL2-associated X protein (BAX) expression. The present study suggests that aspirin can inhibit specific aspects of T cell function by reducing interleukin-10 and transforming growth factor-ß1 secretion via the TIGIT-BCL2-BAX signaling pathway, resulting in improved effector T cell function that inhibits tumor progression.

The neonatal Fc receptor (FcRn) is a pan-arterivirus receptor.

Arteriviruses infect a variety of mammalian hosts, but the receptors used by these viruses to enter cells are poorly understood. We identified the neonatal Fc receptor (FcRn) as an important pro-viral host factor via comparative genome-wide CRISPR-knockout screens with multiple arteriviruses. Using a panel of cell lines and divergent arteriviruses, we demonstrate that FcRn is required for the entry step of arterivirus infection and serves as a molecular barrier to arterivirus cross-species infection. We also show that FcRn synergizes with another known arterivirus entry factor, CD163, to mediate arterivirus entry. Overexpression of FcRn and CD163 sensitizes non-permissive cells to infection and enables the culture of fastidious arteriviruses. Treatment of multiple cell lines with a pre-clinical anti-FcRn monoclonal antibody blocked infection and rescued cells from arterivirus-induced death. Altogether, this study identifies FcRn as a novel pan-arterivirus receptor, with implications for arterivirus emergence, cross-species infection, and host-directed pan-arterivirus countermeasure development.

Avian and Human Influenza A Virus Receptors in Bovine Mammary Gland.

An outbreak of influenza A (H5N1) virus was detected in dairy cows in the United States. We detected influenza A virus sialic acid -α2,3/α2,6-galactose host receptors in bovine mammary glands by lectin histochemistry. Our results provide a rationale for the high levels of H5N1 virus in milk from infected cows.

Structural basis for VLDLR recognition by eastern equine encephalitis virus.

Eastern equine encephalitis virus (EEEV) is the most virulent alphavirus that infects humans, and many survivors develop neurological sequelae, including paralysis and intellectual disability. Alphavirus spike proteins comprise trimers of heterodimers of glycoproteins E2 and E1 that mediate binding to cellular receptors and fusion of virus and host cell membranes during entry. We recently identified very-low density lipoprotein receptor (VLDLR) and apolipoprotein E receptor 2 (ApoER2) as cellular receptors for EEEV and a distantly related alphavirus, Semliki Forest virus (SFV). Here, we use single-particle cryo-electron microscopy (cryo-EM) to determine structures of the EEEV and SFV spike glycoproteins bound to the VLDLR ligand-binding domain and found that EEEV and SFV interact with the same cellular receptor through divergent binding modes. Our studies suggest that the ability of LDLR-related proteins to interact with viral spike proteins through very small footprints with flexible binding modes results in a low evolutionary barrier to the acquisition of LDLR-related proteins as cellular receptors for diverse sets of viruses.

Structure defining of ultrapotent neutralizing nanobodies against MERS-CoV with novel epitopes on receptor binding domain.

The Middle East Respiratory Syndrome Coronavirus (MERS-CoV) causes severe and fatal acute respiratory disease in humans. High fatality rates and continued infectiousness remain a pressing concern for global health preparedness. Antibodies targeted at the receptor-binding domain (RBD) are major countermeasures against human viral infection. Here, we report four potent nanobodies against MERS-CoV, which are isolated from alpaca, and especially the potency of Nb14 is highest in the pseudotyped virus assay. Structural studies show that Nb14 framework regions (FRs) are mainly involved in interactions targeting a novel epitope, which is entirely distinct from all previously reported antibodies, and disrupt the protein-carbohydrate interaction between residue W535 of RBD and hDPP4 N229-linked carbohydrate moiety (hDPP4-N229-glycan). Different from Nb14, Nb9 targets the cryptic face of RBD, which is distinctive from the hDPP4 binding site and the Nb14 epitope, and it induces the ß5-ß6 loop to inflect towards a shallow groove of the RBD and dampens the accommodation of a short helix of hDPP4. The particularly striking epitopes endow the two Nbs administrate synergistically in the pseudotyped MERS-CoV assays. These results not only character unprecedented epitopes for antibody recognition but also provide promising agents for prophylaxis and therapy of MERS-CoV infection.

Structural Characterization of Human Bufavirus 1: Receptor Binding and Endosomal pH-Induced Changes.

Bufaviruses (BuV) are members of the Parvoviridae of the Protoparvovirus genus. They are non-enveloped, T = 1 icosahedral ssDNA viruses isolated from patients exhibiting acute diarrhea. The lack of treatment options and a limited understanding of their disease mechanisms require studying these viruses on a molecular and structural level. In the present study, we utilize glycan arrays and cell binding assays to demonstrate that BuV1 capsid binds terminal sialic acid (SIA) glycans. Furthermore, using cryo-electron microscopy (cryo-EM), SIA is shown to bind on the 2/5-fold wall of the capsid surface. Interestingly, the capsid residues stabilizing SIA binding are conserved in all human BuVs identified to date. Additionally, biophysical assays illustrate BuV1 capsid stabilization during endo-lysosomal (pH 7.4-pH 4) trafficking and capsid destabilization at pH 3 and less, which correspond to the pH of the stomach. Hence, we determined the cryo-EM structures of BuV1 capsids at pH 7.4, 4.0, and 2.6 to 2.8 Å, 3.2 Å, and 2.7 Å, respectively. These structures reveal capsid structural rearrangements during endo-lysosomal escape and provide a potential mechanism for this process. The structural insights gained from this study will add to the general knowledge of human pathogenic parvoviruses. Furthermore, the identification of the conserved SIA receptor binding site among BuVs provides a possible targetable surface-accessible pocket for the design of small molecules to be developed as anti-virals for these viruses.

Chikungunya virus release is reduced by TIM-1 receptors through binding of envelope phosphatidylserine.

T-cell immunoglobin and mucin domain protein-1 (TIM-1) mediates entry of chikungunya virus (CHIKV) into some mammalian cells through the interaction with envelope phospholipids. While this interaction enhances entry, TIM-1 has been shown to tether newly formed HIV and Ebola virus particles, limiting their efficient release. In this study, we investigate the ability of surface receptors such as TIM-1 to sequester newly budded virions on the surface of infected cells. We established a luminescence reporter system to produce chikungunya viral particles that integrate nano-luciferase and easily quantify viral particles. We found that TIM-1 on the surface of host cells significantly reduced CHIKV release efficiency in comparison to other entry factors. Removal of cell surface TIM-1 through direct cellular knock-out or altering the cellular lipid distribution enhanced CHIKV release. Over the course of infection, CHIKV was able to counteract the tethering effect by gradually decreasing the surface levels of TIM-1 in a process mediated by the nonstructural protein 2. This study highlights the importance of phosphatidylserine receptors in mediating not only the entry of CHIKV but also its release and could aid in developing cell lines capable of enhanced vaccine production. IMPORTANCE: Chikungunya virus (CHIKV) is an enveloped alphavirus transmitted by the bites of infectious mosquitoes. Infection with CHIKV results in the development of fever, joint pain, and arthralgia that can become chronic and last for months after infection. Prevention of this disease is still highly focused on vector control strategies. In December 2023, a new live attenuated vaccine against CHIKV was approved by the FDA. We aimed to study the cellular factors involved in CHIKV release, to better understand CHIKV's ability to efficiently infect and spread among a wide variety of cell lines. We found that TIM-1 receptors can significantly abrogate CHIKV's ability to efficiently exit infected cells. This information can be beneficial for maximizing viral particle production in laboratory settings and during vaccine manufacturing.

Shifts in receptors during submergence of an encephalitic arbovirus.

Western equine encephalitis virus (WEEV) is an arthropod-borne virus (arbovirus) that frequently caused major outbreaks of encephalitis in humans and horses in the early twentieth century, but the frequency of outbreaks has since decreased markedly, and strains of this alphavirus isolated in the past two decades are less virulent in mammals than strains isolated in the 1930s and 1940s1-3. The basis for this phenotypic change in WEEV strains and coincident decrease in epizootic activity (known as viral submergence3) is unclear, as is the possibility of re-emergence of highly virulent strains. Here we identify protocadherin 10 (PCDH10) as a cellular receptor for WEEV. We show that multiple highly virulent ancestral WEEV strains isolated in the 1930s and 1940s, in addition to binding human PCDH10, could also bind very low-density lipoprotein receptor (VLDLR) and apolipoprotein E receptor 2 (ApoER2), which are recognized by another encephalitic alphavirus as receptors4. However, whereas most of the WEEV strains that we examined bind to PCDH10, a contemporary strain has lost the ability to recognize mammalian PCDH10 while retaining the ability to bind avian receptors, suggesting WEEV adaptation to a main reservoir host during enzootic circulation. PCDH10 supports WEEV E2-E1 glycoprotein-mediated infection of primary mouse cortical neurons, and administration of a soluble form of PCDH10 protects mice from lethal WEEV challenge. Our results have implications for the development of medical countermeasures and for risk assessment for re-emerging WEEV strains.

Cell-surface d-glucuronyl C5-epimerase binds to porcine deltacoronavirus spike protein facilitating viral entry.

Porcine deltacoronavirus (PDCoV) is an emerging swine enteric coronavirus with zoonotic potential. The coronavirus spike (S) glycoprotein, especially the S1 subunit, mediates viral entry by binding to cellular receptors. However, the functional receptor of PDCoV remains poorly understood. In this study, we used the soluble PDCoV S1 protein as bait to capture the S1-binding cellular transmembrane proteins in combined immunoprecipitation and mass spectrometry analyses. A single guide RNA screen identified d-glucuronyl C5-epimerase (GLCE), a heparan sulfate-modifying enzyme, as a proviral host factor for PDCoV infection. GLCE knockout significantly inhibited the attachment and internalization stages of PDCoV infection. We also demonstrated the interaction between GLCE and PDCoV S with coimmunoprecipitation in both an overexpression system and PDCoV-infected cells. GLCE could be localized to the cell membrane, and an anti-GLCE antibody suppressed PDCoV infection. Although GLCE expression alone did not render nonpermissive cells susceptible to PDCoV infection, GLCE promoted the binding of PDCoV S to porcine amino peptidase N (pAPN), acting synergistically with pAPN to enhance PDCoV infection. In conclusion, our results demonstrate that GLCE is a novel cell-surface factor facilitating PDCoV entry and provide new insights into PDCoV infection. IMPORTANCE: The identification of viral receptors is of great significance, potentially extending our understanding of viral infection and pathogenesis. Porcine deltacoronavirus (PDCoV) is an emerging enteropathogenic coronavirus with the potential for cross-species transmission. However, the receptors or coreceptors of PDCoV are still poorly understood. The present study confirms that d-glucuronyl C5-epimerase (GLCE) is a positive regulator of PDCoV infection, promoting viral attachment and internalization. The anti-GLCE antibody suppressed PDCoV infection. Mechanically, GLCE interacts with PDCoV S and promotes the binding of PDCoV S to porcine amino peptidase N (pAPN), acting synergistically with pAPN to enhance PDCoV infection. This work identifies GLCE as a novel cell-surface factor facilitating PDCoV entry and paves the way for further insights into the mechanisms of PDCoV infection.

TMPRSS2 and glycan receptors synergistically facilitate coronavirus entry.

The entry of coronaviruses is initiated by spike recognition of host cellular receptors, involving proteinaceous and/or glycan receptors. Recently, TMPRSS2 was identified as the proteinaceous receptor for HCoV-HKU1 alongside sialoglycan as a glycan receptor. However, the underlying mechanisms for viral entry remain unknown. Here, we investigated the HCoV-HKU1C spike in the inactive, glycan-activated, and functionally anchored states, revealing that sialoglycan binding induces a conformational change of the NTD and promotes the neighboring RBD of the spike to open for TMPRSS2 recognition, exhibiting a synergistic mechanism for the entry of HCoV-HKU1. The RBD of HCoV-HKU1 features an insertion subdomain that recognizes TMPRSS2 through three previously undiscovered interfaces. Furthermore, structural investigation of HCoV-HKU1A in combination with mutagenesis and binding assays confirms a conserved receptor recognition pattern adopted by HCoV-HKU1. These studies advance our understanding of the complex viral-host interactions during entry, laying the groundwork for developing new therapeutics against coronavirus-associated diseases.

Human coronavirus HKU1 recognition of the TMPRSS2 host receptor.

The human coronavirus HKU1 spike (S) glycoprotein engages host cell surface sialoglycans and transmembrane protease serine 2 (TMPRSS2) to initiate infection. The molecular basis of HKU1 binding to TMPRSS2 and determinants of host receptor tropism remain elusive. We designed an active human TMPRSS2 construct enabling high-yield recombinant production in human cells of this key therapeutic target. We determined a cryo-electron microscopy structure of the HKU1 RBD bound to human TMPRSS2, providing a blueprint of the interactions supporting viral entry and explaining the specificity for TMPRSS2 among orthologous proteases. We identified TMPRSS2 orthologs from five mammalian orders promoting HKU1 S-mediated entry into cells along with key residues governing host receptor usage. Our data show that the TMPRSS2 binding motif is a site of vulnerability to neutralizing antibodies and suggest that HKU1 uses S conformational masking and glycan shielding to balance immune evasion and receptor engagement.

The histamine receptor H1 acts as an alternative receptor for SARS-CoV-2.

Numerous host factors, in addition to human angiotensin-converting enzyme 2 (hACE2), have been identified as coreceptors of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), demonstrating broad viral tropism and diversified druggable potential. We and others have found that antihistamine drugs, particularly histamine receptor H1 (HRH1) antagonists, potently inhibit SARS-CoV-2 infection. In this study, we provided compelling evidence that HRH1 acts as an alternative receptor for SARS-CoV-2 by directly binding to the viral spike protein. HRH1 also synergistically enhanced hACE2-dependent viral entry by interacting with hACE2. Antihistamine drugs effectively prevent viral infection by competitively binding to HRH1, thereby disrupting the interaction between the spike protein and its receptor. Multiple inhibition assays revealed that antihistamine drugs broadly inhibited the infection of various SARS-CoV-2 mutants with an average IC50 of 2.4 µM. The prophylactic function of these drugs was further confirmed by authentic SARS-CoV-2 infection assays and humanized mouse challenge experiments, demonstrating the therapeutic potential of antihistamine drugs for combating coronavirus disease 19.IMPORTANCEIn addition to human angiotensin-converting enzyme 2, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can utilize alternative cofactors to facilitate viral entry. In this study, we discovered that histamine receptor H1 (HRH1) not only functions as an independent receptor for SARS-CoV-2 but also synergistically enhances ACE2-dependent viral entry by directly interacting with ACE2. Further studies have demonstrated that HRH1 facilitates the entry of SARS-CoV-2 by directly binding to the N-terminal domain of the spike protein. Conversely, antihistamine drugs, primarily HRH1 antagonists, can competitively bind to HRH1 and thereby prevent viral entry. These findings revealed that the administration of repurposable antihistamine drugs could be a therapeutic intervention to combat coronavirus disease 19.

Identification of HRH1 as an alternative receptor for SARS-CoV-2: insights from viral inhibition by repurposable antihistamines.

Numerous coreceptors have been shown to facilitate hACE2-dependent or hACE2-independent infection by SARS-CoV-2. A recent study published in mBio by Yu et al. showed that the histamine receptor H1 (HRH1) functions as an alternative receptor for SARS-CoV-2 via direct binding to viral spike proteins (F. Yu, X. Liu, H. Ou, X. Li, et al., mBio e01088-24, 2024, https://doi.org/10.1128/mbio.01088-24). Furthermore, they present compelling evidence that antihistamine drugs targeting HRH1 potently inhibit SARS-CoV-2 entry. This study highlights the therapeutic potential of repurposable antihistamines against COVID-19.