scholarly journals Respiratory Syncytial Virus-Neutralizing Monoclonal Antibodies Motavizumab and Palivizumab Inhibit Fusion

2010 ◽  
Vol 84 (16) ◽  
pp. 8132-8140 ◽  
Author(s):  
Kelly Huang ◽  
Len Incognito ◽  
Xing Cheng ◽  
Nancy D. Ulbrandt ◽  
Herren Wu
Keyword(s):  
Respiratory Syncytial Virus ◽  
Cell Membrane ◽  
Respiratory Disease ◽  
Cell Fusion ◽  
Conformational Changes ◽  
Viral Fusion ◽  
F Protein ◽  
Virus Attachment ◽  
Target Cell Membrane ◽  
Syncytial Virus

ABSTRACT Respiratory syncytial virus (RSV) is a major cause of virus-induced respiratory disease and hospitalization in infants. Palivizumab, an RSV-neutralizing monoclonal antibody, is used clinically to prevent serious RSV-related respiratory disease in high-risk infants. Motavizumab, an affinity-optimized version of palivizumab, was developed to improve protection against RSV. These antibodies bind RSV F protein, which plays a role in virus attachment and mediates fusion. Determining how these antibodies neutralize RSV is important to help guide development of new antibody drugs against RSV and, potentially, other viruses. This study aims to uncover the mechanism(s) by which palivizumab and motavizumab neutralize RSV. Assays were developed to test the effects of these antibodies at distinct steps during RSV replication. Pretreatment of virus with palivizumab or motavizumab did not inhibit virus attachment or the ability of F protein to interact with the target cell membrane. However, pretreatment of virus with either of these antibodies resulted in the absence of detectable viral transcription. These results show that palivizumab and motavizumab act at a point after F protein initiates interaction with the cell membrane and before virus transcription. Palivizumab and motavizumab also inhibited F protein-mediated cell-to-cell fusion. Therefore, these results strongly suggest that these antibodies block both cell-to-cell and virus-to-cell fusion, since these processes are likely similar. Finally, palivizumab and motavizumab did not reduce viral budding. Based on models developed from numerous studies of viral fusion proteins, our results indicate that these antibodies may prevent conformational changes in F protein required for the fusion process.

scholarly journals The cytoplasmic domain of the F protein of Human respiratory syncytial virus is not required for cell fusion

2006 ◽  
Vol 87 (2) ◽  
pp. 395-398 ◽  
Author(s):  
Patrick J. Branigan ◽  
Nicole D. Day ◽  
Changbao Liu ◽  
Lester L. Gutshall ◽  
José A. Melero ◽  
...  
Keyword(s):  
Respiratory Syncytial Virus ◽  
Cell Fusion ◽  
Fusion Proteins ◽  
Cytoplasmic Domain ◽  
Cysteine Residue ◽  
Human Respiratory Syncytial Virus ◽  
Cytoplasmic Domains ◽  
F Protein ◽  
Avian Pneumovirus ◽  
Syncytial Virus

The cytoplasmic domains of the fusion proteins encoded by several viruses play a role in cell fusion and contain sites for palmitoylation associated with viral protein trafficking and virus assembly. The fusion (F) protein of Human respiratory syncytial virus (HRSV) has a predicted cytoplasmic domain of 26 residues containing a single palmitoylated cysteine residue that is conserved in bovine RSV F protein, but not in the F proteins of other pneumoviruses such as pneumonia virus of mice, human metapneumovirus and avian pneumovirus. The cytoplasmic domains in other paramyxovirus fusion proteins such as Newcastle disease virus F protein play a role in fusion. In this study, it was shown that deletion of the entire cytoplasmic domain or mutation of the single cysteine residue (C550S) of the HRSV F protein had no effect on protein processing, cell-surface expression or fusion.

scholarly journals GS-5806 Inhibits a Broad Range of Respiratory Syncytial Virus Clinical Isolates by Blocking the Virus-Cell Fusion Process

2015 ◽  
Vol 60 (3) ◽  
pp. 1264-1273 ◽  
Author(s):  
Michel Perron ◽  
Kirsten Stray ◽  
April Kinkade ◽  
Dorothy Theodore ◽  
Gary Lee ◽  
...  
Keyword(s):  
Respiratory Syncytial Virus ◽  
Cell Fusion ◽  
Clinical Investigation ◽  
Temperature Shift ◽  
Airway Epithelial Cells ◽  
Clinical Isolates ◽  
Cross Resistance ◽  
F Protein ◽  
Syncytial Virus ◽  
Tract Infections

Respiratory syncytial virus (RSV) is a leading cause of lower respiratory tract infections in infants and young children. In addition, RSV causes significant morbidity and mortality in hospitalized elderly and immunocompromised patients. Currently, only palivizumab, a monoclonal antibody against the RSV fusion (F) protein, and inhaled ribavirin are approved for the prophylactic and therapeutic treatment of RSV, respectively. Therefore, there is a clinical need for safe and effective therapeutic agents for RSV infections. GS-5806, discovered via chemical optimization of a hit from a high-throughput antiviral-screening campaign, selectively inhibits a diverse set of 75 RSV subtype A and B clinical isolates (mean 50% effective concentration [EC50] = 0.43 nM). The compound maintained potency in primary human airway epithelial cells and exhibited low cytotoxicity in human cell lines and primary cell cultures (selectivity > 23,000-fold). Time-of-addition and temperature shift studies demonstrated that GS-5806 does not block RSV attachment to cells but interferes with virus entry. Follow-up experiments showed potent inhibition of RSV F-mediated cell-to-cell fusion. RSV A and B variants resistant to GS-5806, due to mutations in F protein (RSV A, L138F or F140L/N517I, and RSV B, F488L or F488S), were isolated and showed cross-resistance to other RSV fusion inhibitors, such as VP-14637, but remained fully sensitive to palivizumab and ribavirin. In summary, GS-5806 is a potent and selective RSV fusion inhibitor with antiviral activity against a diverse set of RSV clinical isolates. The compound is currently under clinical investigation for the treatment of RSV infection in pediatric, immunocompromised, and elderly patients.

scholarly journals Insertion of the Two Cleavage Sites of the Respiratory Syncytial Virus Fusion Protein in Sendai Virus Fusion Protein Leads to Enhanced Cell-Cell Fusion and a Decreased Dependency on the HN Attachment Protein for Activity

2008 ◽  
Vol 82 (12) ◽  
pp. 5986-5998 ◽  
Author(s):  
Joanna Rawling ◽  
Blanca García-Barreno ◽  
José A. Melero
Keyword(s):  
Respiratory Syncytial Virus ◽  
Fusion Protein ◽  
Membrane Fusion ◽  
Cell Fusion ◽  
Sendai Virus ◽  
Cleavage Sites ◽  
Attachment Protein ◽  
F Protein ◽  
Syncytial Virus ◽  
Cell Cell

ABSTRACT Cell entry by paramyxoviruses requires fusion of the viral envelope with the target cell membrane. Fusion is mediated by the viral fusion (F) glycoprotein and usually requires the aid of the attachment glycoprotein (G, H or HN, depending on the virus). Human respiratory syncytial virus F protein (FRSV) is able to mediate membrane fusion in the absence of the attachment G protein and is unique in possessing two multibasic furin cleavage sites, separated by a region of 27 amino acids (pep27). Cleavage at both sites is required for cell-cell fusion. We have investigated the significance of the two cleavage sites and pep27 in the context of Sendai virus F protein (FSeV), which possesses a single monobasic cleavage site and requires both coexpression of the HN attachment protein and trypsin in order to fuse cells. Inclusion of both FRSV cleavage sites in FSeV resulted in a dramatic increase in cell-cell fusion activity in the presence of HN. Furthermore, chimeric FSeV mutants containing both FRSV cleavage sites demonstrated cell-cell fusion in the absence of HN. The presence of two multibasic cleavage sites may therefore represent a strategy to regulate activation of a paramyxovirus F protein for cell-cell fusion in the absence of an attachment protein.

scholarly journals Shifting immunodominance pattern of two cytotoxic T-lymphocyte epitopes in the F glycoprotein of the Long strain of respiratory syncytial virus

2004 ◽  
Vol 85 (11) ◽  
pp. 3229-3238 ◽  
Author(s):  
Carolina Johnstone ◽  
Patricia de León ◽  
Francisco Medina ◽  
José A. Melero ◽  
Blanca García-Barreno ◽  
...  
Keyword(s):  
Respiratory Syncytial Virus ◽  
Vaccinia Virus ◽  
T Lymphocyte ◽  
Cytotoxic T Lymphocyte ◽  
Recombinant Vaccinia Virus ◽  
Recombinant Vaccinia ◽  
F Protein ◽  
Syncytial Virus ◽  
Lymphocyte Responses

Human respiratory syncytial virus (RSV) is a major cause of respiratory infection in children and in the elderly. The RSV fusion (F) glycoprotein has long been recognized as a vaccine candidate as it elicits cytotoxic T-lymphocyte (CTL) and antibody responses. Two murine H-2Kd-restricted CTL epitopes (F85–93 and F92–106) are known in the F protein of the A2 strain of RSV. F-specific CTL lines using BCH4 fibroblasts that are persistently infected with the Long strain of human RSV as stimulators were generated, and it was found that in this strain only the F85–93 epitope is conserved. Motif based epitope prediction programs and an F2 chain deleted F protein encoded in a recombinant vaccinia virus enabled identification of a new epitope in the Long strain, F249–258, which is presented by Kd as a 9-mer (TYMLTNSEL) or a 10-mer (TYMLTNSELL) peptide. The results suggest that the 10-mer might be a naturally processed endogenous Kd ligand. The CD8+ T-lymphocyte responses to epitopes F85–93 and F249–258 present in the F protein of RSV Long were found to be strongly skewed to F85–93 in in vitro multispecific CTL lines and in vivo during a secondary response to a recombinant vaccinia virus that expresses the entire F protein. However, no hierarchy in CD8+ T-lymphocyte responses to F85–93 and F249–258 epitopes was observed in vivo during a primary response.

Immunogenicity and efficacy of codon optimized DNA vaccines encoding the F-protein of respiratory syncytial virus

Vaccine ◽  
2007 ◽  
Vol 25 (41) ◽  
pp. 7271-7279 ◽  
Author(s):  
Nicola Ternette ◽  
Bettina Tippler ◽  
Klaus Überla ◽  
Thomas Grunwald
Keyword(s):  
Respiratory Syncytial Virus ◽  
Dna Vaccines ◽  
F Protein ◽  
Syncytial Virus
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