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Background: Microvascular invasion (MVI) is associated with an unfavorable prognosis and early recurrence of hepatocellular carcinoma (HCC), which is the crucial pathological hallmark of immunotherapy. While microvascular invasion (MVI) in hepatocellular carcinoma (HCC) currently lacks a detailed single-cell analysis of the tumor microenvironment (TME), it holds significant promise for immunotherapy using immune checkpoint inhibitors (ICI). Methods: We performed single-cell RNA sequencing (scRNA-seq) on 3 MVI positive (MVIP) and 14 MVI-negative (MVIN) tumor tissues, as well as their paired adjacent non-tumoral tissues. Results: We identified SPP1+ macrophages and CD4+ proliferative T cells as intertumoral populations critical for the formation of cold tumors and immunosuppressive environments in MVI-positive patients and verified their prognostic value in correlation with MVIP HCC patients. Additionally, we identified SPP1+ dominated interactions between SPP1+ macrophages and the immunosuppressive T population as contributors to MVI destruction and tumorigenesis. Conclusions: We provide a comprehensive single-cell atlas of HCC patients with MVI, shedding light on the immunosuppressive ecosystem and upregulated signaling associated with MVI. These findings demonstrate that intercellular mechanisms drive MVI and provide a potential immunotherapeutic target for HCC patients with HCC and underlying MVI.

The outbreak of African Swine Fever (ASF) has caused huge economic losses to the pig industry. There are no safe and effective vaccines or diagnostics available. The p30 protein serves as a key target for the detection of ASFV antibodies and is an essential antigenic protein for early serological diagnosis. Here, the p30 protein was purified after being expressed in E. coli and its immunogenicity was verified in sera from pigs naturally infected with ASFV. Furthermore, a monoclonal antibody (McAb) designated as McAb 1B4G2–4 (subtype IgG1/kappa-type) was produced and it was verified to specifically recognize the ASFV Pig/HLJ/2018/strain and eukaryotic recombinant ASFV p30 protein. The epitope identified by McAb 1B4G2–4, defining the unique B-cell epitope 164HNFIQTI170, was located using peptide scanning. Comparing amino acid (aa) sequence revealed that this epitope is conserved in all reference ASFV strains from different regions of China, including the highly pathogenic strain Georgia 2007/1 (NC_044959.2) that is widely distributed. It is also exposed to the surface of the p30 protein, suggesting that it could be an important B-cell epitope. Our study may serve as a basis for the development of serological diagnostic methods and subunit vaccines.