ABSTRACT
The ongoing pandemic caused by a monkeypox virus (MPXV) variant has spread all over the world and raised great public health concerns. The DNA polymerase F8 of MPXV, associated with its processivity factors A22 and E4, is responsible for viral genome replication in the perinuclear sites of the infected cells as well as a critical target for developing antiviral drugs. However, the assembly and working mechanism for the DNA polymerase holoenzyme of MPXV remains elusive. Here, we present the cryo-EM structure of the DNA polymerase holoenzyme F8/A22/E4 from the 2022 West African strain at an overall resolution of 3.5 angstrom and revealed the precise spatial arrangement. Surprisingly, unlike any other previously reported B-family DNA polymerase, the holoenzyme complex is assembled as a dimer of heterotrimers, of which the extra interface between the thumb domain of F8 and A22 shows a clash between A22 and substrate DNA , suggesting an auto-inhibition state. Supplying an exogenous double-stranded DNA could notably shift the hexameric form into a trimeric form, which exposes the DNA binding site of thumb domain and might represent a more active state. The structures provide a molecular basis for the design of new antiviral therapeutics that target the MPXV DNA polymerase holoenzyme.
ABSTRACT
Background: In December 2019, a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged in Wuhan and rapidly spread throughout China. The immune response is likely to be highly involved in the pathological process of coronavirus disease 2019 (COVID-19). However, information on specific changes of immune response in COVID-19 are limited. Methods: Demographic and clinical data of all confirmed cases with COVID-19 on admission at Tongji Hospital from January 10 to February 12, 2020, were collected and analyzed. The expression of lymphocytes, lymphocyte subsets, infection related biomarkers and inflammatory cytokines were analyzed and compared between severe cases and non-severe patients. Findings: Of the 452 patients with COVID-19 recruited from January 10 to February 12, 2020, 286 were diagnosed as severe infection. The median age was 58 years and 235 were male. 201 patients had chronic diseases and a higher percentage in the severe cases. The most common symptoms were fever, shortness of breath, expectoration, and fatigue. Severe cases tend to have higher white blood cell and neutrophil lymphopenia ratio (NLR), as well as lower percentages of monocytes, eosinophils, and basophils. Most of severe cases demonstrated elevated levels of infection-related biomarkers, and inflammatory cytokines. The numbers of B cells, T cells and NK cells was significantly decreased in patients with COVID-19, and more severely decreased in the severe cases. T cells were shown to be most affected by SARS-CoV-2, and more hampered in severe cases. Both helper T cells and suppressor T cells in patients with COVID-19 were below normal levels. Helper T cells tend to be more affected in severe cases. The percentage of naïve helper T cells increased and memory helper T cells decreased in severe cases. Patients with COVID-19 have lower level of regulatory T cells, and more obviously damaged in severe cases. Interpretation: SARS-CoV-2 might mainly act on lymphocytes, especially T lymphocytes, and induce a cytokine storm in the body, generate a series of immune responses. Surveillance of NLR and lymphocyte subsets is helpful in the early screening of critical illness, diagnosis and treatment of COVID-19.Funding Statement: None.Declaration of Interests: All authors declare no competing interests.Ethics Approval Statement: The study was performed in accordance with Tongji Hospital Ethics Committee (IRB ID: TJ-C20200121). Written informed consent was waived by the Ethics Commission of the designated hospital for emerging infectious disease.
Subject(s)
Coronavirus Infections , Communicable Diseases, Emerging , Chronic Disease , COVID-19 , LymphopeniaABSTRACT
Abstract Background In December 2019, coronavirus disease 2019 (COVID-19) emerged in Wuhan and rapidly spread throughout China. Methods Demographic and clinical data of all confirmed cases with COVID-19 on admission at Tongji Hospital from January 10 to February 12, 2020, were collected and analyzed. The data of laboratory examinations, including peripheral lymphocyte subsets, were analyzed and compared between severe and non-severe patients. Results Of the 452 patients with COVID-19 recruited, 286 were diagnosed as severe infection. The median age was 58 years and 235 were male. The most common symptoms were fever, shortness of breath, expectoration, fatigue, dry cough and myalgia. Severe cases tend to have lower lymphocytes counts, higher leukocytes counts and neutrophil-lymphocyte-ratio (NLR), as well as lower percentages of monocytes, eosinophils, and basophils. Most of severe cases demonstrated elevated levels of infection-related biomarkers and inflammatory cytokines. The number of T cells significantly decreased, and more hampered in severe cases. Both helper T cells and suppressor T cells in patients with COVID-19 were below normal levels, and lower level of helper T cells in severe group. The percentage of naïve helper T cells increased and memory helper T cells decreased in severe cases. Patients with COVID-19 also have lower level of regulatory T cells, and more obviously damaged in severe cases. Conclusions The novel coronavirus might mainly act on lymphocytes, especially T lymphocytes. Surveillance of NLR and lymphocyte subsets is helpful in the early screening of critical illness, diagnosis and treatment of COVID-19.