Mutant Fusion Proteins with Enhanced Fusion Activity Promote Measles Virus Spread in Human Neuronal Cells and Brains of Suckling Hamsters

Watanabe, Shumpei; Shirogane, Yuta; Suzuki, Satoshi; Ikegame, Satoshi; Koga, Ritsuko; Yanagi, Yusuke

doi:10.1128/jvi.02632-12

Cited by 61 publications

(118 citation statements)

References 69 publications

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“…However, we found that most SSPE strains possess amino acid substitutions in the extracellular domain of the F protein (29). Our study revealed that the substitutions found in multiple SSPE strains, T461I and S103I/N462S/N465S, confer enhanced fusion activity on the F protein.…”

mentioning

confidence: 71%

“…The plasmids pCA7-ICH and pCA7-ICF that encode the H and F proteins of the pathogenic IC-B strain of MV, respectively, were established previously (17), using the eukaryotic expression vector pCA7 (31), a derivative of pCAGGS (32). The expression plasmids which express mutant F protein, pCA7-ICF(T461I) and pCA7-ICF(S103I/N462S/N465S), were described previously (29). The full-length genome plasmids pHHRz(ϩ) MV323-Luci and pHHRz(ϩ)MV323-F(T461I)-Luci were, respectively, generated from pHHRz(ϩ)MV323-EGFP and pHHRz(ϩ)MV323-F(T461I)-EGFP (29,33), which encode the antigenomic full-length cDNA of the IC-B strain with the wild-type or mutant F protein (T461I), together with the enhanced green fluorescent protein (EGFP).…”

Section: Methodsmentioning

confidence: 99%

“…Our study revealed that the substitutions found in multiple SSPE strains, T461I and S103I/N462S/N465S, confer enhanced fusion activity on the F protein. Furthermore, recombinant viruses with these fusion-enhancing mutations induced syncytium formation even in SLAMand nectin 4-negative cells, including human neuroblastoma cell lines and Vero cells, and exhibited neurovirulence in suckling hamsters, unlike the parental wild-type MV (29).…”

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confidence: 99%

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Measles Virus Mutants Possessing the Fusion Protein with Enhanced Fusion Activity Spread Effectively in Neuronal Cells, but Not in Other Cells, without Causing Strong Cytopathology

Watanabe

Ohno

Shirogane

et al. 2015

J Virol

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Subacute sclerosing panencephalitis (SSPE) is caused by persistent measles virus (MV) infection in the central nervous system (CNS). Since human neurons, its main target cells, do not express known MV receptors (signaling lymphocyte activation molecule [SLAM] and nectin 4), it remains to be understood how MV infects and spreads in them. We have recently reported that fusion-enhancing substitutions in the extracellular domain of the MV fusion (F) protein (T461I and S103I/N462S/N465S), which are found in multiple SSPE virus isolates, promote MV spread in human neuroblastoma cell lines and brains of suckling hamsters. In this study, we show that hyperfusogenic viruses with these substitutions also spread efficiently in human primary neuron cultures without inducing syncytia. These substitutions were found to destabilize the prefusion conformation of the F protein trimer, thereby enhancing fusion activity. However, these hyperfusogenic viruses exhibited stronger cytopathology and produced lower titers at later time points in SLAM-or nectin 4-expressing cells compared to the wild-type MV. Although these viruses spread efficiently in the brains of SLAM knock-in mice, they did not in the spleens. Taken together, the results suggest that enhanced fusion activity is beneficial for MV to spread in neuronal cells where no cytopathology occurs, but detrimental to other types of cells due to strong cytopathology. Acquisition of enhanced fusion activity through substitutions in the extracellular domain of the F protein may be crucial for MV's extensive spread in the CNS and development of SSPE. IMPORTANCE Subacute sclerosing panencephalitis (SSPE) is a fatal disease caused by persistent measles virus (MV) infection in the central nervous system (CNS).Its cause is not well understood, and no effective therapy is currently available. Recently, we have reported that enhanced fusion activity of MV through the mutations in its fusion protein is a major determinant of efficient virus spread in human neuronal cells and brains of suckling hamsters. In this study, we show that those mutations render the conformation of the fusion protein less stable, thereby making it hyperfusogenic. Our results also show that enhanced fusion activity is beneficial for MV to spread in the CNS but detrimental to other types of cells in peripheral tissues, which are strongly damaged by the virus. Our findings provide important insight into the mechanism for the development of SSPE after MV infection. M easles is a highly contagious disease characterized by high fever, cough, and maculopapular rash (1). The causative agent, measles virus (MV), is thought to first infect alveolar macrophages and dendritic cells of the respiratory tract, which transport the virus to local lymph nodes, where it replicates efficiently (2, 3). This allows MV to spread to other lymphoid organs throughout the body via the bloodstream, followed by infection of respiratory epithelia at later stages. Progeny viral particles are then shed from the epithelial cells through ...

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confidence: 71%

Section: Methodsmentioning

confidence: 99%

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confidence: 99%

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Measles Virus Mutants Possessing the Fusion Protein with Enhanced Fusion Activity Spread Effectively in Neuronal Cells, but Not in Other Cells, without Causing Strong Cytopathology

Watanabe

Ohno

Shirogane

et al. 2015

J Virol

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“…Interestingly, this phenotype correlated with enhanced F-mediated membrane fusion activity in SLAM-and nectin-4-negative cells (66). Some of the MeV F mutations described in this study are likewise located proximal to the central F pocket microdomain (Fig.…”

Section: Fig 12mentioning

confidence: 85%

“…Residues highlighted in red (V447T and L372A) and yellow (L326A and P331A) were identified in this study and shown to increase fusion by destabilizing the prefusion F trimer. Residues highlighted in blue (S262 [66] and G264 [65]) were reported to influence cell-cell fusion and viral pathogenicity.…”

Section: Fig 12mentioning

confidence: 99%

Molecular Determinants Defining the Triggering Range of Prefusion F Complexes of Canine Distemper Virus

Avila

Alves

Khosravi

et al. 2014

J Virol

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The morbillivirus cell entry machinery consists of a fusion (F) protein trimer that refolds to mediate membrane fusion following receptor-induced conformational changes in its binding partner, the tetrameric attachment (H) protein. To identify molecular determinants that control F refolding, we generated F chimeras between measles virus (MeV) and canine distemper virus (CDV). We located a central pocket in the globular head domain of CDV F that regulates the stability of the metastable, prefusion conformational state of the F trimer. Most mutations introduced into this "pocket'" appeared to mediate a destabilizing effect, a phenotype associated with enhanced membrane fusion activity. Strikingly, under specific triggering conditions (i.e., variation of receptor type and H protein origin), some F mutants also exhibited resistance to a potent morbillivirus entry inhibitor, which is known to block F triggering by enhancing the stability of prefusion F trimers. Our data reveal that the molecular nature of the F stimulus and the intrinsic stability of metastable prefusion F both regulate the efficiency of F refolding and escape from smallmolecule refolding blockers. IMPORTANCEWith the aim to better characterize the thermodynamic basis of morbillivirus membrane fusion for cell entry and spread, we report here that the activation energy barrier of prefusion F trimers together with the molecular nature of the triggering "stimulus" (attachment protein and receptor types) define a "triggering range," which governs the initiation of the membrane fusion process. A central "pocket" microdomain in the globular F head contributes substantially to the regulation of the conformational stability of the prefusion complexes. The triggering range also defines the mechanism of viral escape from entry inhibitors and describes how the cellular environment can affect membrane fusion efficiency.

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Subacute sclerosing panencephalitis

Garg

Mahadevan

Malhotra

et al. 2019

Reviews in Medical Virology

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Summary Subacute sclerosing panencephalitis (SSPE) is a slowly progressive brain disorder caused by mutant measles virus. SSPE affects younger age groups. SSPE incidence is proportional to that of measles. High‐income countries have seen substantial decline in SSPE incidence following universal vaccination against measles. SSPE virus differs from wild measles virus. Measles virus genome recovered from the autopsied brain tissues demonstrates clustered mutations in virus genome particularly in the M gene. These mutations destroy the structure and functioning of the encoded proteins. Complete infectious virus particle has rarely been recovered from the brain. Human neurons lack required receptor for entry of measles virus inside the neurons. Recent in vitro studies suggest that mutations in F protein confer hyperfusogenic properties to measles virus facilitating transneuronal viral spread. The inflammatory response in the brain leads to extensive tissue damage. Clinically, SSPE is characterized by florid panencephalitis. Clinically, SSPE is characterized by cognitive decline, periodic myoclonus, gait abnormalities, vision loss, and ultimately to a vegetative state. Chorioretinitis is a common ocular abnormality. Electroencephalography (EEG) shows characteristic periodic discharges. Neuroimaging demonstrates periventricular white matter signal abnormalities. In advanced stages, there is marked cerebral atrophy. Definitive diagnosis requires demonstration of elevated measles antibody titers in cerebrospinal fluid (CSF). Many drugs have been used to stabilize the course of the disease but without evidence from randomized clinical trials. Six percent of patients may experience prolonged spontaneous remission. Fusion inhibitor peptide may, in the future, be exploited to treat SSPE. A universal vaccination against measles is the only proven way to tackle this menace currently.

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Mutant Fusion Proteins with Enhanced Fusion Activity Promote Measles Virus Spread in Human Neuronal Cells and Brains of Suckling Hamsters

Cited by 61 publications

References 69 publications

Measles Virus Mutants Possessing the Fusion Protein with Enhanced Fusion Activity Spread Effectively in Neuronal Cells, but Not in Other Cells, without Causing Strong Cytopathology

Measles Virus Mutants Possessing the Fusion Protein with Enhanced Fusion Activity Spread Effectively in Neuronal Cells, but Not in Other Cells, without Causing Strong Cytopathology

Molecular Determinants Defining the Triggering Range of Prefusion F Complexes of Canine Distemper Virus

Subacute sclerosing panencephalitis

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