Immune defense against infection with the hepatitis B virus (HBV) is complex and involves both host innate and adaptive immune systems. It is well accepted that the development of sufficient HBV-specific T cell and B cell responses are required for controlling an HBV infection. However, the contribution of innate immunity to removing HBV has been explored in recent years. Toll-like receptors (TLRs) are recognized as the first line of antiviral immunity because they initiate intracellular signaling pathways to induce antiviral mediators such as interferons (IFNs) and other cytokines. Recent studies show that the activation of TLR-mediated signaling pathways results in a suppression of HBV replication in vitro and in vivo. However, HBV has also evolved strategies to counter TLR responses including the suppression of TLR expression and the blockage of downstream signaling pathways. Antiviral treatment in chronic HBV-infected patients leads to an upregulation of TLR expression and the restoration of its innate antiviral functions. Thus, TLR activation may serve as an additional immunotherapeutic option for treating chronic HBV infection in combination with antiviral treatment.

Objectives: Comorbidities have significant indications for the disease outcome of COVID-19, however which underlying diseases that contribute the most to aggravate the conditions of COVID-19 patients is still largely unknown. SARS-CoV-2 viral clearance is a golden standard for defining the recovery of COVID-19 infections. To dissect the underlying diseases that could impact on viral clearance, we enrolled 106 COVID-19 patients who were hospitalized in the Zhongnan Hospital of Wuhan University, Wuhan, China between Jan 5 and Feb 25, 2020. Methodology: We comprehensively analyzed demographic, clinical and laboratory data, as well as patient treatment records. Survival analyses with Kaplan-Meier and Cox regression modelling were employed to identify factors influencing the viral clearance negatively. Results: We found that increasing age, male gender, and angiotensin-converting enzyme 2 (ACE2) associated factors (including hypertension, diabetes, and cardiovascular diseases) adversely affected the viral clearance. Furthermore, analysis by a random forest survival model pointed out hypertension, cortisone treatment, gender, and age as the four most important variables. Conclusions: We conclude that patients at old age, males, and/or having diseases associated with high expression of ACE2 will have worse prognosis during a COVID-19 infections.

Summary: Background: Viral clearance is one important indicator for the recovery of SARS-CoV-2 infected patients. Previous studies have pointed out that suboptimal T and B cell responses can delay viral clearance in MERS-CoV and SARS-CoV infected patients. The role of leukomonocytes in viral clearance of COVID-19 patients is not yet well defined. Methods: From January 26 to February 28, 2020, an observational study was launched at the Department of Infectious Diseases, Zhongnan Hospital of Wuhan University, Wuhan, China. We enrolled 25 laboratory-confirmed COVID-19 patients, whose throat-swab specimens were tested positive for SARS-CoV-2 infection by qRT-PCR. To investigate the factors that contribute to the viral clearance, we comprehensively analyzed clinical records, counts of lymphocyte subsets including CD3+, CD4+, CD8+ T cells, B cells and NK cells in the patients who successfully cleared SARS-CoV-2, and compared to those that failed to, after a standardized treatment of 8-14 days. Findings: In 25 enrolled COVID-19 patients, lymphopenia was a common feature. After the treatment, 14 out of the 25 enrolled patients were tested negative for SARS-CoV-2. The patients that cleared the infection had restored the numbers of CD3+, CD4+, CD8+ T cells and B cells as compared to the still viral RNA positive patients, while the recovered patients had a higher count of leukomonocytes. Conclusions: By comparison of leukomonocytes counts in COVID-19 patients at different stages of the disease, we found that CD3+, CD4+, CD8+ T cells and B cells appear to play important roles in viral clearance. The restoration of leukomonocytes counts from peripheral blood can be used as prognosis for the recovery of an COVID-19 infection. We propose that restoration of leukomonocytes counts can be added to the COVID-19 diagnostic guidance as a criterion for releasing and discharging patients.

TLR2 serves as a costimulatory molecule on activated T cells. However, it is unknown how the functionality and antiviral activity of CD8⁺ T cells are modulated by direct TLR2 signaling. In this study, we looked at the TLR2-mediated enhancement of TCR-driven CD8⁺ T cell activation in vitro and in woodchuck hepatitis virus transgenic mice. In vitro stimulation of CD8⁺ T cells purified from C57BL/6 mice showed that TLR2 agonist Pam3CSK4 directly enhanced the TCR-dependent CD8⁺ T cell activation. Transcriptome analysis revealed that TLR2 signaling increased expression of bioenergy metabolism-related genes in CD8⁺ T cells, such as IRF4, leading to improved glycolysis and glutaminolysis. This was associated with the upregulation of genes related to immune regulation and functions such as T-bet and IFN-γ. Glycolysis and glutaminolysis were in turn essential for the TLR2-mediated enhancement of T cell activation. Administration of TLR2 agonist Pam3CSK4 promoted the expansion and functionality of vaccine-primed, Ag-specific CD8⁺ T cells in both wild type and transgenic mice and improved viral suppression. Thus, TLR2 could promote CD8⁺ T cell immunity through regulating the energy metabolism. Key Points TLR2 directly regulates the anti-CD3–activated CD8⁺ T cells independently on APCs. Bioenergy metabolism is important for TLR2-mediated enhancement of CD8⁺ T cells. TLR2 enhances the antiviral CD8⁺ T cell response and the efficacy of HBV vaccine.

Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) led to the outbreak of pneumonia in Wuhan. The virus is highly infectious. Patients with cancer might be susceptible to the viral infection because of the immunosuppressive state cause by therapies on tumors. Case presentation: We present the clinical features of four cancer patients who were infected with SARS-CoV-2 in late January of 2020 in our hospital. Cases 1 and 3 were diagnosed as mild and common type of coronavirus disease 2019 (COVID-2019) and survived from the viral infection. They acquired SARS-CoV-2 infection during their staying in hospital under radiotherapy and surgery of the tumors. Cases 2 and 4 suffered from severe type of COVID-19, and Case 2 was dead owning to the advanced age, uncontrolled chronic B cell lymphocytic leukemia and many other underlying diseases. The immunosuppressive state induced by liver transplantation and anti-rejection therapy might contribute to the severity of COVID-19 in Case 4, who suffered from hepatitis B related hepatocellular carcinoma. However, Case 4 was recovered from COVID-19 after a combination therapy against virus, bacteria and fungi, and also respiratory support. Nearly all patients showed a decrease in lymphocytes including total CD3⁺ T cells, B cells, and natural killer cells after infection of the virus. Conclusions: The severity of COVID-19 might be influenced by immune system state and underlying diseases in cancer patients. And the treatment of SARS-CoV-2 infection in cancer patients is challenged by the immunosuppressive state of these patients under chemotherapy or surgery.

Background & Aims: The coronavirus disease 2019 (COIVD-19) caused by SARS-CoV-2 has been characterized as a pandemic, which causes a serious public health challenge in the world. A very large group of patients infected by HBV has been reported worldwide, especially in China. In order to answer whether specific treatment strategy on the patients coinfected with HBV and SARS-CoV-2, it requires profound understanding of the clinical characteristics on those patients. However, the impacts of SARS-CoV-2 infection on HBV patients remain largely unknown. Approach & Results: In this retrospective investigation, we included 123 COVID-19 patients admitted to Zhongnan Hospital of Wuhan University, Wuhan, China, from January 5 to March 7, 2020. All enrolled patients are the laboratory confirmed COVID-19 pneumonia cases according to the criteria reported previously. A total of 123 patients were analyzed for their Clinical records, laboratory results including the diagnosis of HBV infection and liver function. Among 123 confirmed COVID-19 patients, the mean age was 51 years old and 59.3% were females (73/123). Fifteen were previously HBV infected patients, 66.7% of them were males (10/15), patients with HBV infection appeared to have a higher incidence of liver cirrhosis and an increased level of total bilirubin. Seven (46.7%) patients with HBV infection were defined as severe cases, while the severity rate was 24.1% for the patients without HBV infection (26/108). The mortality of patients with HBV infection was 13.3% (2/15) compared to 2.8% (3/108) for the patients without HBV infection. Conclusions: SARS-CoV-2 infection may cause Live function damage in COVID-19 cases and the patients with HBV infection are likely to have more severe disease outcome.