scholarly journals A recombinant fragment of Human surfactant protein D binds Spike protein and inhibits infectivity and replication of SARS-CoV-2 in clinical samples

2020 ◽  
Author(s):  
Taruna Madan ◽  
Barnali Biswas ◽  
Praveen M. Varghese ◽  
Rambhadur Subedi ◽  
Hrishikesh Pandit ◽  
...  
Keyword(s):  
Immune Surveillance ◽  
Cell Receptor ◽  
Surfactant Protein ◽  
Spike Protein ◽  
Clinical Samples ◽  
Surfactant Protein D ◽  
Amino Acid Residues ◽  
Recombinant Fragment ◽  
Acute Infectious Disease

AbstractRationaleCOVID-19 is an acute infectious disease caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Human surfactant protein D (SP-D) is known to interact with spike protein of SARS-CoV, but its immune-surveillance against SARS-CoV-2 is not known.ObjectiveThis study aimed to examine the potential of a recombinant fragment of human SP-D (rfhSP-D) as an inhibitor of replication and infection of SARS-CoV-2.MethodsrfhSP-D interaction with spike protein of SARS-CoV-2 and hACE-2 receptor was predicted via docking analysis. The inhibition of interaction between spike protein and ACE-2 by rfhSP-D was confirmed using direct and indirect ELISA. The effect of rfhSP-D on replication and infectivity of SARS-CoV-2 from clinical samples was studied by measuring the expression of RdRp gene of the virus using qPCR.Measurements and Main ResultsIn-silico interaction studies indicated that three amino acid residues in the RBD of spike of SARS-CoV-2 were commonly involved in interacting with rfhSP-D and ACE-2. Studies using clinical samples of SARS-CoV-2 positive cases (asymptomatic, n=7 and symptomatic, n=8 and negative controls n=15) demonstrated that treatment with 5μM rfhSP-D inhibited viral replication by ~5.5 fold and was more efficient than Remdesivir (100 μM). Approximately, a 2-fold reduction in viral infectivity was also observed after treatment with 5μM rfhSP-D.ConclusionsThese results conclusively demonstrate that the calcium independent rfhSP-D mediated inhibition of binding between the receptor binding domain of the S1 subunit of the SARS-CoV-2 spike protein and human ACE-2, its host cell receptor, and a significant reduction in SARS-CoV-2 infection and replication in-vitro.

scholarly journals Identification of Common Deletions in the Spike Protein of Severe Acute Respiratory Syndrome Coronavirus 2

2020 ◽  
Vol 94 (17) ◽  
Author(s):  
Zhe Liu ◽  
Huanying Zheng ◽  
Huifang Lin ◽  
Mingyue Li ◽  
Runyu Yuan ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Virus Replication ◽  
Receptor Binding ◽  
Cleavage Site ◽  
Spike Protein ◽  
Clinical Samples ◽  
Receptor Binding Domain ◽  
Flanking Sequence

ABSTRACT Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel coronavirus first identified in December 2019. Notable features that make SARS-CoV-2 distinct from most other previously identified betacoronaviruses include a receptor binding domain and a unique insertion of 12 nucleotides or 4 amino acids (PRRA) at the S1/S2 boundary. In this study, we identified two deletion variants of SARS-CoV-2 that either directly affect the polybasic cleavage site itself (NSPRRAR) or a flanking sequence (QTQTN). These deletions were verified by multiple sequencing methods. In vitro results showed that the deletion of NSPRRAR likely does not affect virus replication in Vero and Vero-E6 cells; however, the deletion of QTQTN may restrict late-phase viral replication. The deletion of QTQTN was detected in 3 of 68 clinical samples and 12 of 24 in vitro-isolated viruses, while the deletion of NSPRRAR was identified in 3 in vitro-isolated viruses. Our data indicate that (i) there may be distinct selection pressures on SARS-CoV-2 replication or infection in vitro and in vivo; (ii) an efficient mechanism for deleting this region from the viral genome may exist, given that the deletion variant is commonly detected after two rounds of cell passage; and (iii) the PRRA insertion, which is unique to SARS-CoV-2, is not fixed during virus replication in vitro. These findings provide information to aid further investigation of SARS-CoV-2 infection mechanisms and a better understanding of the NSPRRAR deletion variant observed here. IMPORTANCE The spike protein determines the infectivity and host range of coronaviruses. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has two unique features in its spike protein, the receptor binding domain and an insertion of 12 nucleotides at the S1/S2 boundary resulting in a furin-like cleavage site. Here, we identified two deletion variants of SARS-CoV-2 that either directly affect the furin-like cleavage site itself (NSPRRAR) or a flanking sequence (QTQTN), and we investigated these deletions in cell isolates and clinical samples. The absence of the polybasic cleavage site in SARS-CoV-2 did not affect virus replication in Vero or Vero-E6 cells. Our data indicate the PRRAR sequence and the flanking QTQTN sequence are not fixed in vitro; thus, there appears to be distinct selection pressures on SARS-CoV-2 sequences in vitro and in vivo. Further investigation of the mechanism of generating these deletion variants and their infectivity in different animal models would improve our understanding of the origin and evolution of this virus.

scholarly journals Surfactant Protein D Increases Phagocytosis of Hypocapsular Cryptococcus neoformans by Murine Macrophages and Enhances Fungal Survival

2009 ◽  
Vol 77 (7) ◽  
pp. 2783-2794 ◽  
Author(s):  
Scarlett Geunes-Boyer ◽  
Timothy N. Oliver ◽  
Guilhem Janbon ◽  
Jennifer K. Lodge ◽  
Joseph Heitman ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Defense Mechanisms ◽  
Protein A ◽  
Surfactant Protein ◽  
Immune Defense ◽  
Surfactant Protein D ◽  
Wild Type ◽  
Phagocytic Cells

ABSTRACT Cryptococcus neoformans is a facultative intracellular opportunistic pathogen and the leading cause of fungal meningitis in humans. In the absence of a protective cellular immune response, the inhalation of C. neoformans cells or spores results in pulmonary infection. C. neoformans cells produce a polysaccharide capsule composed predominantly of glucuronoxylomannan, which constitutes approximately 90% of the capsular material. In the lungs, surfactant protein A (SP-A) and SP-D contribute to immune defense by facilitating the aggregation, uptake, and killing of many microorganisms by phagocytic cells. We hypothesized that SP-D plays a role in C. neoformans pathogenesis by binding to and enhancing the phagocytosis of the yeast. Here, the abilities of SP-D to bind to and facilitate the phagocytosis and survival of the wild-type encapsulated strain H99 and the cap59Δ mutant hypocapsular strain are assessed. SP-D binding to cap59Δ mutant cells was approximately sixfold greater than binding to wild-type cells. SP-D enhanced the phagocytosis of cap59Δ cells by approximately fourfold in vitro. To investigate SP-D binding in vivo, SP-D−/− mice were intranasally inoculated with Alexa Fluor 488-labeled cap59Δ or H99 cells. By confocal microscopy, a greater number of phagocytosed C. neoformans cells in wild-type mice than in SP-D−/− mice was observed, consistent with in vitro data. Interestingly, SP-D protected C. neoformans cells against macrophage-mediated defense mechanisms in vitro, as demonstrated by an analysis of fungal viability using a CFU assay. These findings provide evidence that C. neoformans subverts host defense mechanisms involving surfactant, establishing a novel virulence paradigm that may be targeted for therapy.

scholarly journals A Recombinant Fragment of Human Surfactant Protein D Lacking the Short Collagen-Like Stalk Fails to Correct Morphological Alterations in Lungs of SP-D Deficient Mice

2009 ◽  
Vol 292 (2) ◽  
pp. 183-189 ◽  
Author(s):  
Lars Knudsen ◽  
Katharina Wucherpfennig ◽  
Rose-Marie Mackay ◽  
Paul Townsend ◽  
Christian Mühlfeld ◽  
...  
Keyword(s):  
Surfactant Protein ◽  
Surfactant Protein D ◽  
Recombinant Fragment ◽  
Morphological Alterations ◽  
Deficient Mice

Assessment of the antiviral properties of recombinant surfactant protein D against influenza B virus in vitro

2015 ◽  
Vol 195 ◽  
pp. 43-46 ◽  
Author(s):  
Marine L.B. Hillaire ◽  
Martin van Eijk ◽  
Stella E. Vogelzang-van Trierum ◽  
Nella J. Nieuwkoop ◽  
Debby van Riel ◽  
...  
Keyword(s):  
Surfactant Protein ◽  
Influenza B Virus ◽  
Surfactant Protein D ◽  
Influenza B ◽  
B Virus

scholarly journals S‐Nitrosylation of Surfactant Protein D (SP‐D) modulates its oligomerization and inflammatory function in vitro and in experimental models of lung injury.

2007 ◽  
Vol 21 (5) ◽  
Author(s):  
Elena N Atochina‐Vasserman ◽  
Helen Abramova ◽  
Yaniv Tomer ◽  
Helchem Kadire ◽  
Deepika Jain ◽  
...  
Keyword(s):  
Lung Injury ◽  
Surfactant Protein ◽  
Experimental Models ◽  
Surfactant Protein D

Identification of a common deletion in the spike protein of SARS-CoV-2

2020 ◽  
Author(s):  
Zhe Liu ◽  
Huanying Zheng ◽  
Runyu Yuan ◽  
Mingyue Li ◽  
Huifang Lin ◽  
...  
Keyword(s):  
Protein Function ◽  
Cleavage Site ◽  
Vaccine Development ◽  
Mechanistic Explanation ◽  
Spike Protein ◽  
Clinical Samples ◽  
Genomic Changes ◽  
And Function

AbstractTwo notable features have been identified in the SARS-CoV-2 genome: (1) the receptor binding domain of SARS-CoV-2; (2) a unique insertion of twelve nucleotide or four amino acids (PRRA) at the S1 and S2 boundary. For the first feature, the similar RBD identified in SARs-like virus from pangolin suggests the RBD in SARS-CoV-2 may already exist in animal host(s) before it transmitted into human. The left puzzle is the history and function of the insertion at S1/S2 boundary, which is uniquely identified in SARS-CoV-2. In this study, we identified two variants from the first Guangdong SARS-CoV-2 cell strain, with deletion mutations on polybasic cleavage site (PRRAR) and its flank sites. More extensive screening indicates the deletion at the flank sites of PRRAR could be detected in 3 of 68 clinical samples and half of 22 in vitro isolated viral strains. These data indicate (1) the deletion of QTQTN, at the flank of polybasic cleavage site, is likely benefit the SARS-CoV-2 replication or infection in vitro but under strong purification selection in vivo since it is rarely identified in clinical samples; (2) there could be a very efficient mechanism for deleting this region from viral genome as the variants losing 23585-23599 is commonly detected after two rounds of cell passage. The mechanistic explanation for this in vitro adaptation and in vivo purification processes (or reverse) that led to such genomic changes in SARS-CoV-2 requires further work. Nonetheless, this study has provided valuable clues to aid further investigation of spike protein function and virus evolution. The deletion mutation identified in vitro isolation should be also noted for current vaccine development.

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