Residues of the Human Metapneumovirus Fusion (F) Protein Critical for Its Strain-Related Fusion Phenotype: Implications for the Virus Replication Cycle

Más, Vicente; Herfst, Sander; Osterhaus, Albert D. M. E.; Fouchier, Ron A. M.; Melero, José A.

doi:10.1128/jvi.05485-11

Cited by 23 publications

(49 citation statements)

References 48 publications

(63 reference statements)

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“…The F protein of aMPV subtype B, but not A and C, requires trypsin for cell-cell fusion. In addition, the F proteins of all three aMPV subtypes do not require low pH for cell-cell fusion, which is in contrast to the fusion requirement of some hMPV strains (21,31,42,43).…”

Section: Discussionmentioning

confidence: 86%

“…Since the G attachment protein is not required for F protein triggering in pneumoviruses, it is not clear what triggers the F proteins of pneumoviruses. While it has been proposed that low pH triggers the fusion of hMPV F protein through protonation of H435 (42), emerging evidence indicates that low-pH-induced membrane fusion mediated by the hMPV F protein is a rare and strain-dependent phenomenon (21,31). Indeed, only 6% of hMPV lineage A strains may require low pH for triggering, whereas all known hMPV lineage B strains and the majority of lineage A strains do not require low pH for fusion, suggesting that low pH is not a general trigger for hMPV F protein.…”

Section: Discussionmentioning

confidence: 99%

“…Although aMPV F proteins promoted cell-cell fusion at pH 7.0, we cannot exclude the possibility that lower pH enhances their fusion-promoting activities. Indeed, the F proteins of some hMPV strains require low pH for cell-cell fusion (21,31,42,43). To further elucidate the role of pH in aMPV fusion, we evaluated the fusion activities of aMPV F proteins at lower pH.…”

Section: Distinct Phenotypes Of Cell-cell Fusion Promoted By F Proteimentioning

confidence: 99%

“…In addition, recombinant aMPV lacking the G protein can be recovered by reverse genetics, suggesting that aMPV G protein is not essential for aMPV entry (19,35). In contrast to all other paramyxoviruses, fusion of some hMPV strains requires low pH (21,31,42,43). In addition, it has been suggested that hMPV F protein utilizes ␣v␤1 integrin as a cellular receptor based on the evidence that hMPV F protein possesses an integrin binding motif and integrin promotes hMPV infection (12).…”

mentioning

confidence: 99%

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Localization of a Region in the Fusion Protein of Avian Metapneumovirus That Modulates Cell-Cell Fusion

Wei

Feng²,

Yao³

et al. 2012

J Virol

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eThe genus Metapneumovirus within the subfamily Pneumovirinae of the family Paramyxoviridae includes two members, human metapneumovirus (hMPV) and avian metapneumovirus (aMPV), causing respiratory tract infections in humans and birds, respectively. Paramyxoviruses enter host cells by fusing the viral envelope with a host cell membrane. Membrane fusion of hMPV appears to be unique, in that fusion of some hMPV strains requires low pH. Here, we show that the fusion (F) proteins of aMPV promote fusion in the absence of the attachment protein and low pH is not required. Furthermore, there are notable differences in cell-cell fusion among aMPV subtypes. Trypsin was required for cell-cell fusion induced by subtype B but not subtypes A and C. The F protein of aMPV subtype A was highly fusogenic, whereas those from subtypes B and C were not. By construction and evaluation of chimeric F proteins composed of domains from the F proteins of subtypes A and B, we localized a region composed of amino acid residues 170 to 338 in the F protein that is responsible for the hyperfusogenic phenotype of the F from subtype A. Further mutagenesis analysis revealed that residues R295, G297, and K323 in this region collectively contributed to the hyperfusogenicity. Taken together, we have identified a region in the aMPV F protein that modulates the extent of membrane fusion. A model for fusion consistent with these data is presented.T he subfamily Pneumovirinae of the family Paramyxoviridae includes a number of significant human and animal respiratory pathogens, such as human respiratory syncytial virus (hRSV), bovine RSV (bRSV), human metapneumovirus (hMPV), avian metapneumovirus (aMPV), and pneumonia virus of mice (PVM). The major cytopathic effect in paramyxovirus-infected culture cells is the formation of multinucleate syncytia. This is mediated by membrane fusion induced by surface glycoprotein spikes (reviewed in reference 24). For viruses in the Paramyxovirinae subfamily, it is firmly established that membrane fusion requires a specific interaction between two glycoproteins, the attachment protein (HN, H, or G) and the fusion (F) protein (1,9,14,15,23,39), and such fusion occurs at neutral pH (4,27). Specifically, it is thought that the binding of the attachment protein to cell surface receptors triggers major conformational changes in F, which in turn activates membrane fusion (1,27,29,30,39).However, membrane fusion of pneumoviruses appears to be unique among the paramyxoviruses, in that fusion is accomplished by the F protein alone without help from the attachment glycoprotein (6,7,17,21,42,43). This suggests that the F proteins of pneumoviruses possess dual functions, receptor binding and fusion promotion. To date, RSV F is arguably the best characterized F protein within the Pneumovirus subfamily. The F protein of RSV is capable of causing membrane fusion and initiating virus infection in the absence of its attachment G glycoprotein at neutral pH (6, 57). Furthermore, it has been demonstrated that RSV F specifically recognize...

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Section: Discussionmentioning

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Section: Distinct Phenotypes Of Cell-cell Fusion Promoted By F Proteimentioning

confidence: 99%

mentioning

confidence: 99%

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Localization of a Region in the Fusion Protein of Avian Metapneumovirus That Modulates Cell-Cell Fusion

Wei

Feng²,

Yao³

et al. 2012

J Virol

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“…This attachment protein-independent fusion activation has been well characterized in human RSV, bovine RSV, and ovine RSV (14)(15)(16). Recently, it was found that the F proteins of hMPV and aMPV also induce fusion without their attachment G proteins (17)(18)(19)(20), suggesting that the G protein is dispensable for attachment and fusion. Consistent with this observation, recombinant hMPV lacking the G protein was found to replicate efficiently in cell culture (21).…”

Section: H Uman Metapneumovirus (Hmpv) Is a Member Of The Genusmentioning

confidence: 89%

Roles of the Putative Integrin-Binding Motif of the Human Metapneumovirus Fusion (F) Protein in Cell-Cell Fusion, Viral Infectivity, and Pathogenesis

Wei

Zhang

Cai

et al. 2014

J Virol

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Human metapneumovirus (hMPV) is a relatively recently identified paramyxovirus that causes acute upper and lower respiratory tract infection. Entry of hMPV is unusual among the paramyxoviruses, in that fusion is accomplished by the fusion (F) protein without the attachment glycoprotein (G protein). It has been suggested that hMPV F protein utilizes integrin ␣v␤1 as a cellular receptor. Consistent with this, the F proteins of all known hMPV strains possess an integrin-binding motif ( 329 RGD 331 ). The role of this motif in viral entry, infectivity, and pathogenesis is poorly understood. Here, we show that ␣5␤1 and ␣v integrins are essential for cell-cell fusion and hMPV infection. Mutational analysis found that residues R329 and G330 in the 329 RGD 331 motif are essential for cell-cell fusion, whereas mutations at D331 did not significantly impact fusion activity. Furthermore, fusion-defective RGD mutations were either lethal to the virus or resulted in recombinant hMPVs that had defects in viral replication in cell culture. In cotton rats, recombinant hMPV with the R329K mutation in the F protein (rhMPV-R329K) and rhMPV-D331A exhibited significant defects in viral replication in nasal turbinates and lungs. Importantly, inoculation of cotton rats with these mutants triggered a high level of neutralizing antibodies and protected against hMPV challenge. Taken together, our data indicate that (i) ␣5␤1 and ␣v integrins are essential for cell-cell fusion and viral replication, (ii) the first two residues in the RGD motif are essential for fusion activity, and (iii) inhibition of the interaction of the integrin-RGD motif may serve as a new target to rationally attenuate hMPV for the development of live attenuated vaccines. IMPORTANCEHuman metapneumovirus (hMPV) is one of the major causative agents of acute respiratory disease in humans. Currently, there is no vaccine or antiviral drug for hMPV. hMPV enters host cells via a unique mechanism, in that viral fusion (F) protein mediates both attachment and fusion activity. Recently, it was suggested that hMPV F protein utilizes integrins as receptors for entry via a poorly understood mechanism. Here, we show that ␣5␤1 and ␣v integrins are essential for hMPV infectivity and F proteinmediated cell-cell fusion and that the integrin-binding motif in the F protein plays a crucial role in these functions. Our results also identify the integrin-binding motif to be a new, attenuating target for the development of a live vaccine for hMPV. These findings not only will facilitate the development of antiviral drugs targeting viral entry steps but also will lead to the development new live attenuated vaccine candidates for hMPV.

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Hemagglutinin stability as a key determinant of influenza A virus transmission via air

Tosheva,

Saygan,

Mijnhardt

et al. 2023

Current Opinion in Virology

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Residues of the Human Metapneumovirus Fusion (F) Protein Critical for Its Strain-Related Fusion Phenotype: Implications for the Virus Replication Cycle

Cited by 23 publications

References 48 publications

Localization of a Region in the Fusion Protein of Avian Metapneumovirus That Modulates Cell-Cell Fusion

Localization of a Region in the Fusion Protein of Avian Metapneumovirus That Modulates Cell-Cell Fusion

Roles of the Putative Integrin-Binding Motif of the Human Metapneumovirus Fusion (F) Protein in Cell-Cell Fusion, Viral Infectivity, and Pathogenesis

Hemagglutinin stability as a key determinant of influenza A virus transmission via air

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