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Kaposi sarcoma-associated herpesvirus (KSHV) is an oncogenic virus that causes Kaposi sarcoma, primary effusion lymphoma and multicentric Castleman disease. A vaccine that prevents KSHV infection or serves in the treatment of KSHV-related diseases represents a critical unmet need, however, the types of immune responses a vaccine should elicit have not been well defined. The gH/gL glycoprotein complex is an important target of KSHV-neutralizing antibodies, but the epitope specificities targeted by these antibodies remain unknown. Here, we isolated 12 gH/gL-specific monoclonal antibodies (mAbs) from KSHV-infected donors and performed structure/function analyses. These mAbs bind recombinant gH/gL with nanomolar affinities and epitope binning analyses revealed that the mAbs bind to 5 epitope clusters on gH/gL. Seven mAbs were able to neutralize KSHV infection of epithelial cell lines. Two potent neutralizing mAbs mapped to the EphA2 binding site as determined by inhibition of the receptor-ligand interaction and negative stain electron microscopy (nsEM) of the mAb/gH/gL complex. The epitopes of other neutralizing mAbs targeting novel sites of vulnerability were determined by a combination of cryogenic electron microscopy and nsEM. Together, these mAbs help to define the relevant epitope targets for KSHV vaccine design, have utility in understanding the role of antibodies in preventing KSHV infection, enable the development of immunotherapy approaches, and provide valuable tools to understand the molecular details of the KSHV entry process. Author summaryKSHV is an oncogenic virus that can cause cancer in infected individuals. The virus is most prevalent in sub-Saharan Africa and in men who have sex with men. It is possible this virus could be prevented with an effective vaccine, however, the immune response to this virus has not been well defined. gH/gL, a protein essential for viral fusion, plays an important role in infection and could be a possible vaccine target. To better understand the antibody response to this protein, we sought to isolate and characterize monoclonal antibodies that can bind gH/gL and neutralize viral infection. In this study, we isolate and characterize twelve monoclonal antibodies that could bind to five different regions of the gH/gL protein. Seven of these antibodies can neutralize infection, with two being able to block the gH/gL EphA2 receptor-ligand interaction.

CD8+ T cells and natural killer (NK) cells are the primary defenses against tumor cells. The tumor microenvironment impairs their antitumor capabilities, including the ability to infiltrate the tumor. Our laboratory has shown that tumors suppress T cells by inhibiting KCa3.1 K+ channel activity that controls cytokine release, cytotoxicity, and chemotaxis. However, little is known about the role of K+ channels in the anti-tumor activity of NK cells. Here, we investigated KCa3.1 channels¡¯ role in human NK cell function in head and neck squamous cell carcinoma (HNSCC). Selective blockade of KCa3.1 using TRAM-34 inhibited chemotaxis of NK cells from both healthy donors and patients with HNSCC, while KCa3.1pharmacological activation increased chemotaxis and cytotoxicity. SKA-31, a selective KCa3.1 activator, enhanced antitumor immune responses in a humanized HNSCC mouse model generated by implanting Cal27 cells and healthy donor peripheral blood mononuclear cells into immunodeficient mice. SKA-31 treatment resulted in a 7-fold increase in total NK cells and a 23-fold increase in functionally active (granzyme B-positive) NK cells in these tumors. These data highlight the critical role of KCa3.1 channels in antitumor immunity and open the possibility of targeting KCa3.1 to develop new immunotherapies for HNSCC.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-20101-x.

Solid tumor malignancy (STM) patients experience increased risk of breakthrough SARS-CoV-2 infection owing to reduced COVID-19 vaccine immunogenicity. However, the underlying immunological causes of impaired neutralization remain poorly characterized. Furthermore, non-neutralizing antibody functions can contribute to reduced disease severity but remain understudied within high-risk populations. We dissected polyfunctional antibody responses in STM patients and age-matched controls who received adenoviral vector- or mRNA-based COVID-19 vaccine regimens. Elevated inflammatory biomarkers, including agalactosylated IgG, interleukin (IL)-6, IL-18, and an expanded population of CD11c?CD21? double negative 3 (DN3) B cells were observed in STM patients and were associated with impaired neutralization. In contrast, mRNA vaccination induced Fc effector functions that were comparable in patients and controls and were cross-reactive against SARS-CoV-2 variants. These data highlight the resilience of Fc functional antibodies and identify systemic inflammatory biomarkers that may underpin impaired neutralizing antibody responses, suggesting potential avenues for immunomodulation via rational vaccine design.