scholarly journals Decreased Dependence on Receptor Recognition for the Fusion Promotion Activity of L289A-Mutated Newcastle Disease Virus Fusion Protein Correlates with a Monoclonal Antibody-Detected Conformational Change

2005 ◽  
Vol 79 (2) ◽  
pp. 1180-1190 ◽  
Author(s):  
Jianrong Li ◽  
Vanessa R. Melanson ◽  
Anne M. Mirza ◽  
Ronald M. Iorio
Keyword(s):  
Newcastle Disease Virus ◽  
Conformational Change ◽  
Disease Virus ◽  
Cell Lines ◽  
Newcastle Disease ◽  
Energy Requirement ◽  
Target Cells ◽  
F Protein ◽  
Viral Hemagglutinin ◽  
Receptor Recognition

ABSTRACT It has been shown that the L289A-mutated Newcastle disease virus (NDV) fusion (F) protein gains the ability to promote fusion of Cos-7 cells independent of the viral hemagglutinin-neuraminidase (HN) protein and exhibits a 50% enhancement in HN-dependent fusion over wild-type (wt) F protein. Here, we show that HN-independent fusion by L289A-F is not exhibited in BHK cells or in several other cell lines. However, similar to the results in Cos-7 cells, the mutated protein plus HN does promote 50 to 70% more fusion above wt levels in all of the cell lines tested. L289A-F protein exhibits the same specificity as the wt F protein for the homologous HN protein, as well as NDV-human parainfluenza virus 3 HN chimeras. The mutated F protein promotes fusion more effectively than the wt when it is coexpressed with either the chimeras or HN proteins deficient in receptor recognition activity. In addition, its fusogenic activity is significantly more resistant to removal of sialic acid on target cells. These findings are consistent with the demonstration that L289A-F interacts more efficiently with wt and mutated HN proteins than does wt F by a cell surface coimmunoprecipitation assay. Taken together, these findings indicate that L289A-F promotes fusion by a mechanism analogous to that of the wt protein with respect to the HN-F interaction but is less dependent on the attachment activity of HN. The phenotype of the mutated F protein correlates with a conformational change in the protein detectable by two different monoclonal antibodies. This conformational change may reflect a destabilization of F structure induced by the L289A substitution, which may in turn indicate a lower energy requirement for fusion activation.

scholarly journals Role of Thiol/Disulfide Exchange in Newcastle Disease Virus Entry

2008 ◽  
Vol 83 (1) ◽  
pp. 241-249 ◽  
Author(s):  
Surbhi Jain ◽  
Lori W. McGinnes ◽  
Trudy G. Morrison
Keyword(s):  
Newcastle Disease Virus ◽  
Disease Virus ◽  
Conformational Changes ◽  
Newcastle Disease ◽  
Disulfide Bonds ◽  
Early Stage ◽  
Protein S ◽  
Host Cells ◽  
Target Cells ◽  
F Protein

ABSTRACT Newcastle disease virus (NDV) entry into host cells is mediated by the hemagglutinin-neuraminidase (HN) and fusion (F) glycoproteins. We previously showed that production of free thiols in F protein is required for membrane fusion directed by F protein (S. Jain et al., J. Virol. 81:2328-2339, 2007). In the present study we evaluated the oxidation state of F protein in virions and virus-like particles and its relationship to activation of F protein by HN protein, F protein conformational intermediates, and virus-cell fusion. F protein, in particles, does not have free thiols, but free thiols were produced upon binding of particles to target cells. Free thiols were produced at 16°C in F protein in virions bound to the target cells. They also appeared in different fusion defective mutant F proteins. Free thiols were produced in the presence of mutant HN proteins that are defective in F protein activation but are attachment competent. These results suggest that free thiols appear prior to any of the proposed major conformational changes in F protein which accompany fusion activation. These results also indicate that HN protein binding to its receptor likely facilitates the interaction between F protein and host cell isomerases, leading to reduction of disulfide bonds in F protein. Taken together, these results show that free thiols are produced in F protein at a very early stage during the onset of fusion and that the production of free thiols is required for fusion in addition to activation by HN protein.

scholarly journals Mutated Form of the Newcastle Disease Virus Hemagglutinin-Neuraminidase Interacts with the Homologous Fusion Protein despite Deficiencies in both Receptor Recognition and Fusion Promotion

2004 ◽  
Vol 78 (10) ◽  
pp. 5299-5310 ◽  
Author(s):  
Jianrong Li ◽  
Edward Quinlan ◽  
Anne Mirza ◽  
Ronald M. Iorio
Keyword(s):  
Newcastle Disease Virus ◽  
Disease Virus ◽  
Viral Entry ◽  
Newcastle Disease ◽  
Active Site ◽  
Specific Interaction ◽  
Cellular Receptors ◽  
Dimer Interface ◽  
F Protein ◽  
Receptor Recognition

ABSTRACT The Newcastle disease virus (NDV) hemagglutinin-neuraminidase (HN) protein mediates attachment to cellular receptors. The fusion (F) protein promotes viral entry and spread. However, fusion is dependent on a virus-specific interaction between the two proteins that can be detected at the cell surface by a coimmunoprecipitation assay. A point mutation of I175E in the neuraminidase (NA) active site converts the HN of the Australia-Victoria isolate of the virus to a form that can interact with the F protein despite negligible receptor recognition and fusion-promoting activities. Thus, I175E-HN could represent a fusion intermediate in which HN and F are associated and primed for the promotion of fusion. Both the attachment and fusion-promoting activities of this mutant HN protein can be rescued either by NA activity contributed by another HN protein or by a set of four substitutions at the dimer interface. These substitutions were identified by the evaluation of chimeras composed of segments from HN proteins derived from two different NDV strains. These findings suggest that the I175E substitution converts HN to an F-interactive form, but it is one for which receptor binding is still required for fusion promotion. The data also indicate that the integrity of the HN dimer interface is critical to its receptor recognition activity.

scholarly journals Inhibition of Receptor Binding Stabilizes Newcastle Disease Virus HN and F Protein-Containing Complexes

2006 ◽  
Vol 80 (6) ◽  
pp. 2894-2903 ◽  
Author(s):  
L. W. McGinnes ◽  
T. G. Morrison
Keyword(s):  
Newcastle Disease Virus ◽  
Disease Virus ◽  
Receptor Binding ◽  
Newcastle Disease ◽  
Protein Complexes ◽  
Target Cells ◽  
Protein Cleavage ◽  
Protein Activity ◽  
Neuraminidase Treatment ◽  
F Protein

ABSTRACT Receptor binding of paramyxovirus attachment proteins and the interactions between attachment and fusion (F) proteins are thought to be central to activation of the F protein activity; however, mechanisms involved are unclear. To explore the relationships between Newcastle disease virus (NDV) HN and F protein interactions and HN protein attachment to sialic acid receptors, HN and F protein-containing complexes were detected and quantified by reciprocal coimmunoprecipitation from extracts of transfected avian cells. To inhibit HN protein receptor binding, cells transfected with HN and F protein cDNAs were incubated with neuraminidase from the start of transfection. Under these conditions, no fusion was observed, but amounts of HN and F protein complexes increased twofold over amounts detected in extracts of untreated cells. Stimulation of attachment by incubation of untransfected target cells with neuraminidase-treated HN and F protein-expressing cells resulted in a twofold decrease in amounts of HN and F protein complexes. In contrast, high levels of complexes containing HN protein and an uncleaved F protein (F-K115Q) were detected, and those levels were unaffected by neuraminidase treatment of cell monolayers or by incubation with target cells. These results suggest that HN and F proteins reside in a complex in the absence of receptor binding. Furthermore, the results show that not only receptor binding but also F protein cleavage are necessary for disassociation of the HN and F protein-containing complexes.

scholarly journals Newcastle Disease Virus Establishes Persistent Infection in Tumor Cells In Vitro: Contribution of the Cleavage Site of Fusion Protein and Second Sialic Acid Binding Site of Hemagglutinin-Neuraminidase

2017 ◽  
Vol 91 (16) ◽  
Author(s):  
Udaya S. Rangaswamy ◽  
Weijia Wang ◽  
Xing Cheng ◽  
Patrick McTamney ◽  
Danielle Carroll ◽  
...  
Keyword(s):  
Newcastle Disease Virus ◽  
Disease Virus ◽  
Receptor Binding ◽  
Newcastle Disease ◽  
Persistent Infection ◽  
Cleavage Site ◽  
Protein Cleavage ◽  
F Protein ◽  
Sialic Acid Binding

ABSTRACT Newcastle disease virus (NDV) is an oncolytic virus being developed for the treatment of cancer. Following infection of a human ovarian cancer cell line (OVCAR3) with a recombinant low-pathogenic NDV, persistent infection was established in a subset of tumor cells. Persistently infected (PI) cells exhibited resistance to superinfection with NDV and established an antiviral state, as demonstrated by upregulation of interferon and interferon-induced genes such as myxoma resistance gene 1 (Mx1) and retinoic acid-inducing gene-I (RIG-I). Viruses released from PI cells induced higher cell-to-cell fusion than the parental virus following infection in two tumor cell lines tested, HT1080 and HeLa, and remained attenuated in chickens. Two mutations, one in the fusion (F) protein cleavage site, F117S (F117S), and another in hemagglutinin-neuraminidase (HN), G169R (HN169R), located in the second sialic acid binding region, were responsible for the hyperfusogenic phenotype. F117S improves F protein cleavage efficiency, facilitating cell-to-cell fusion, while HN169R possesses a multifaceted role in contributing to higher fusion, reduced receptor binding, and lower neuraminidase activity, which together result in increased fusion and reduced viral replication. Thus, establishment of persistent infection in vitro involves viral genetic changes that facilitate efficient viral spread from cell to cell as a potential mechanism to escape host antiviral responses. The results of our study also demonstrate a critical role in the viral life cycle for the second receptor binding region of the HN protein, which is conserved in several paramyxoviruses. IMPORTANCE Oncolytic Newcastle disease virus (NDV) could establish persistent infection in a tumor cell line, resulting in a steady antiviral state reflected by constitutively expressed interferon. Viruses isolated from persistently infected cells are highly fusogenic, and this phenotype has been mapped to two mutations, one each in the fusion (F) and hemagglutinin-neuraminidase (HN) proteins. The F117S mutation in the F protein cleavage site improved F protein cleavage efficiency while the HN169R mutation located at the second receptor binding site of the HN protein contributed to a complex phenotype consisting of a modest increase in fusion and cell killing, lower neuraminidase activity, and reduced viral growth. This study highlights the intricate nature of these two mutations in the glycoproteins of NDV in the establishment of persistent infection. The data also shed light on the critical balance between the F and HN proteins required for efficient NDV infection and their role in avian pathogenicity.

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