ABSTRACT
Increasing evidence supports inter-species transmission of SARS-CoV-2 variants from human to domestic or wild animals during the ongoing COVID-19 pandemic, which is posing great challenges to epidemic control. Clarifying the host range of emerging SARS-CoV-2 variants will provide instructive information for the containment of viral spillover. The spike protein (S) of SARS-CoV-2 is the key determinant of receptor utilization, and therefore amino acid mutations on S will probably alter viral host range. Here, in order to evaluate the impact of S mutations, we constructed 20 Hela cell lines stably expressing ACE2 orthologs from different animals, and prepared 27 pseudotyped SARS-CoV-2 carrying different spike mutants, among which 20 bear single mutation and the other 7 were cloned from emerging SARS-CoV-2 variants, including D614G, Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.135), Lambda (B.1.429) and Mu (B.1.525). Using pseudoviral reporter assay, we identified that the substitutions of T478I and N501Y enabled the pseudovirus to utilize chicken ACE2, indicating potential infectivity to avian species. Furthermore, the S mutants of real SARS-CoV-2 variants comprising N501Y showed significantly acquired abilities to infect cells expressing mouse ACE2, indicating a critical role of N501Y in expanding SARS-CoV-2 host range. In addition, A262S and T478I significantly enhanced the utilization of various mammals ACE2. In summary, our results indicated that T478I and N501Y substitutions were two S mutations important for receptor adaption of SARS-CoV-2, potentially contributing to spillover of the virus to many other animal hosts. Therefore, more attention should be paid to SARS-CoV-2 variants with these two mutations.
ABSTRACT
Coronavirus pandemics have become a huge threat to the public health worldwide in the recent decades. Typically, SARS-CoV caused SARS pandemic in 2003 and SARS-CoV-2 caused the COVID-19 pandemic recently. Both viruses have been reported to originate from bats. Thus, direct or indirect interspecies transmission from bats to humans is required for the viruses to cause pandemics. Receptor utilization is a key factor determining the host range of viruses which is critical to the interspecies transmission. Angiotensin converting enzyme 2 (ACE2) is the receptor of both SARS-CoV and SARS-CoV-2, but only ACE2s of certain animals can be utilized by the viruses. Here, we employed pseudovirus cell-entry assay to evaluate the receptor-utilizing capability of ACE2s of 20 animals by the two viruses and found that SARS-CoV-2 utilized less ACE2s than SARS-CoV, indicating a narrower host range of SARS-CoV-2. Meanwhile, pangolin CoV, another SARS-related coronavirus highly homologous to SARS-CoV-2 in its genome, yet showed similar ACE2 utilization profile with SARS-CoV rather than SARS-CoV-2. To clarify the mechanism underlying the receptor utilization, we compared the amino acid sequences of the 20 ACE2s and found 5 amino acid residues potentially critical for ACE2 utilization, including the N-terminal 20th and 42nd amino acids that may determine the different receptor utilization of SARS-CoV, SARS-CoV-2 and pangolin CoV. Our studies promote the understanding of receptor utilization of pandemic coronaviruses, potentially contributing to the virus tracing, intermediate host screening and epidemic prevention for pathogenic coronaviruses.
ABSTRACT
The novel human coronavirus (SARS-CoV-2) causes the coronavirus disease 2019 (COVID-19) pandemic worldwide. The increasing sequencing data have shown abundant single nucleotide variations in SARS-CoV-2 genome. However, it is difficult to quickly analyze genomic variation and screen key mutations of SARS-CoV-2. In this study, we developed a visual program, named BioAider, for quick and convenient sequence annotation and mutation analysis on multiple genome-sequencing data. Using BioAider, we conducted a comprehensive genome variation analysis on 3,240 sequences of SARS-CoV-2 genome. Herein, we detected 14 substitution hotspots within SARS-CoV-2 genome, including 10 non-synonymous and 4 synonymous ones. Among these hotspots, NSP13-Y541C was predicted to be a crucial substitution which might affect the unwinding activity of NSP13, a key protein for viral replication. Besides, we also found 3 groups of potentially linked substitution hotspots which were worth further study. In particular, we discovered a SR-rich region (aa 184-204) on the N protein of SARS-CoV-2 distinct from SARS-CoV, indicating more complex replication mechanism and unique N-M interaction of SARS-CoV-2. Interestingly, the quantity of SRXX repeat fragments in the SR-rich region well reflected the evolutionary relationship among SARS-CoV-2 and SARS-CoV-2 related animal coronaviruses, providing further evidence of its animal origin. Overall, we developed an efficient tool for rapid identification of mutations, identified substitution hotspots in SARS-CoV-2 genomes, and detected a distinctive polymorphism SR-rich region in N protein. This tool and the detected hotspots could facilitate the viral genomic study and may contribute for screening antiviral target sites.
ABSTRACT
Objective To investigate the effect of CYP46A1 on the pathogenesis of Alzheimer's disease.Methods Recombinant lentiviral vectors which including anthropogenic CYP46A1 were injected into bilateral hippocampus of 3-monthold male 5XFAD transgenic mice,while empty vectors were injected into the corresponding position of the control group.After two months,the ability of learning and memory were tested by Morris water maze and T maze experiments,and amyloid plaque and inflammatory infiltration in the brain were detected by immunohistochemical staining and ELISA respectively.Results Compared with the control group,CYP46A1 virus injection significantly increased the CYP46A1 mRNA and protein expression in hippocampus.In addition,CYP46A1 overexpression significantly decreased the latency to find the platform in Morris water maze test and increased the correct rate to choose in T maze test.Aβ immunohistochemical staining and plaques area statistics demonstrated that the amyloid plaque area of hippocampus in CYP46A1 overexpression mice was significantly reduced,and there was a significantly decrease of hippocampal astrocytes expression by means of GFAP staining.Furthermore,hippocampal CYP46A1 overexpression significantly decreased the expression level of Aβ40,Aβ42,IL-1β and TNF-α,while compare with the control group.Conclusion CYP46A1 overexpression in hippocampus can promote the cognitive impairment,as well as ameliorate the brain inflammatory infiltration in 5XFAD transgenic mice,suggesting that CYP46A1 has anti-Alzheimer's disease like effects.
ABSTRACT
Biotechnology supremacy is a newly-advanced power theory. It is a superior dominance of military biotechnological application based on the microcosm of life structure within a certain period of time. The advancement of biotechnology supremacy and modern biotechnology has created the concept of bio-micro-frontier, which involves information and defense resources of all living ultra-micro-organisms with national and regional characteristics. Being feasible both in theory and practice, the implementation of bio-micro-frontier system is strategically important. This article explores the implementation of bio-micro-frontier in terms of strategy and tactics, which will add a unique dimension to future military transformation and active defense.
ABSTRACT
Objective To determine the effectiveness of preoperative sedation with rectal midazolam and atropine alone or combined with ketamine in infants and young children.Methods One-hundred and six ASA Ⅰ or Ⅱ infants and young children aged 2 months-2 years scheduled for elective general surgical operation were studied in a double blind fashion.The patients were randomly divided into 3 groups:group M received rectal atropine 0.02 mg?kg~(-1) and midazolam 0.5 mg?kg~(-1)(n=39);group MK and MKK received rectal atropine 0.02 mg?kg~(-1), midazolam 0.5 mg?kg~(-1) and ketamine 4 mg?kg~(-1)(MK,n=34)or 8 mg?kg~(-1)(MKK,n=33).The patients were transferred from the ward to the operating room(OR)30 min after rectal administration.Depth of sedation was evaluated before and 15 min after rectal administration; when the patients were separated from their parents and on arrival in OR using De Jong's sedation score system.SpO_2 and HR were monitored in OR.Results The patients were better sedated in group MK and MKK than in group M after rectal administration.Significantly more patients were asleep on seperation from their parents and on arrival in OR in group MK and MKK than in group M. Significantly more patients were calm and not crying at venepuncture in group MKK(63%)and group MK(32%) than in group M(18%).Conclusion Rectal midazolam combined with ketamine and atropine results in better preoperative sedation than rectal midazolam alone in infants and young children.
