Hantaviruses infection causing severe emerging diseases with high mortality rates in humans has become public health concern globally. The potential roles of CD4⁺T cells in viral control have been extensively studied. However, the contribution of CD4⁺T cells to the host response against Hantaan virus (HTNV) infection remains unclear. Here, based on the T-cell epitopes mapped on HTNV glycoprotein, we studied the effects and characteristics of CD4⁺T-cell responses in determining the outcome of hemorrhagic fever with renal syndrome. A total of 79 novel 15-mer T-cell epitopes on the HTNV glycoprotein were identified, among which 20 peptides were dominant target epitopes. Importantly, we showed the presence of both effective Th1 responses with polyfunctional cytokine secretion and ThGranzyme B⁺ cell responses with cytotoxic mediators production against HTNV infection. The HTNV glycoprotein-specific CD4⁺T-cell responses inversely correlated with the plasma HTNV RNA load in patients. Individuals with milder disease outcomes showed broader epitopes targeted and stronger CD4⁺T-cell responses against HTNV glycoproteins compared with more severe patients. The CD4⁺T cells characterized by broader antigenic repertoire, stronger polyfunctional responses, better expansion capacity and highly differentiated effector memory phenotype(CD27^-CD28^-CCR7^-CD45RA-CD127^hi) would elicit greater defense against HTNV infection and lead to much milder outcome of the disease. The host defense mediated by CD4⁺T cells may through the inducing antiviral condition of the host cells and cytotoxic effect of ThGranzyme B⁺ cells. Thus, these findings highlight the efforts of CD4⁺T-cell immunity to HTNV control and provide crucial information to better understand the immune defense against HTNV infection. Hantaan virus (HTNV), the prototype of Hantavirus genus, is a rodent-borne pathogen that causes human hemorrhagic fever with renal syndrome, with mortality rate of approximately 15% in Asia. The efforts of our immune system to defend against HTNV are important for clearance of the infection. However, the interaction between CD4⁺T-cell immunity and HTNV infection in humans is not known. Based on the novel T-cell epitopes we defined on HTNV glycoprotein in Chinese Han population, we confirmed that HTNV glycoprotein could induce vigorous and extensive CD4⁺T-cell response in humans. For the first time, we showed that both Th1 and ThGranzyme B⁺ cell responses involved in defense against HTNV infection and inversely correlated with plasma viral load and disease outcome. Additionally, we found that CD4⁺T cells characterized by broader antigenic repertoire, polyfunctional cytokine secretion, stronger expansion and highly differentiated effector memory phenotype always lead to much milder outcome of the disease, maybe through inducing antiviral condition of host cells and cytotoxic effect of ThGranzyme B⁺ cells. Our results add weight to the contribution of CD4⁺T cells in disease control after HTNV infection in humans, which may greatly advance the understanding about how HTNV interact with their host organisms.

Malignant tumors typically undergo an atavistic regression characterized by the overexpression of embryonic genes and proto-oncogenes, including a variety of cancer/testis antigens (CTAs) that are testis-derived and are not expressed or expressed in trace amounts in somatic tissues. Based on this theory, we established a new method to identify unknown CTAs, the spermatogenic cells-specific monoclonal antibody-defined cancer/testis antigen (SADA) method. Using the SADA method, we identified BAP31 as a novel CTA and confirmed that BAP31 expression is associated with progression and metastasis of several cancers, particularly in cervical cancer. We found that BAP31 was significantly upregulated in stage I, II, and III cervical cancer patients and highly correlated with poor clinic outcomes. We further demonstrated that BAP31 regulates cervical cancer cell proliferation by arresting the cell cycle at the G0/G1 stage and that depletion of BAP31 inhibits hyper-proliferation. Moreover, depletion of BAP31 inhibits cervical cancer cell invasion and migration by regulating the expression and subcellular localization of Drebrin, M-RIP, SPECC1L, and Nexilin, and then affect the cytoskeleton assemblage. Finally, the depletion of BAP31 prevents cervical cancer progression and metastasis in vivo. These findings provide a new method for identifying novel CTAs as well as mechanistic insights into how BAP31 regulates cervical cancer hyper-proliferation and metastasis.

To investigate the role of viral load in the pathogenesis of hemorrhagic fever with renal syndrome, the Hantaan virus RNA load in plasma from 101 patients was quantified, and the relationships between viral load and disease course, severity, and level of specific humoral immunity were analyzed. The viral load, detectable in 79 patients, ranged from 3.43 to 7.33 log₁₀ copies/mL of plasma. In the early stage of disease, patients in severe/critical group were found to have higher viral loads than those in the mild/moderate group (5.90 vs 5.03 log₁₀ copies/mL; P = .001), suggesting an association between Hantaan virus load and disease severity.

Natural killer (NK) cells play a critical role in antitumor immunity, and the activation of NK cells is regulated by a series of NK cell receptors. Here, we show that crosslinking CD226, an important NK cell receptor, with the anti‐CD226 mAb LeoA1 on NKL cells, regulated the expression of several microRNA and transmembrane tumor necrosis factor‐α. Among them, miR‐30c‐1* was noticed because overexpression of miR‐30c‐1^* triggered upregulation of transmembrane tumor necrosis factor‐α expression and enhanced NK cell cytotoxicity against hepatoma cell lines SMMC‐7721 and HepG2. Furthermore, we proved that the inhibitory transcription factor HMBOX1, which depressed the activation of NK cells, was the direct target gene of miR‐30c‐1^*. In conclusion, our results revealed a novel regulatory mechanism: miR‐30c‐1^* promoted NK cell cytotoxicity against hepatoma cells by targeting HMBOX1. (Cancer Sci 2012; 103: 645–652)