Evidence map›Paper›PMID 42439560›Full record

ArticlemBio2026

Functional dissection of HCMV gB's autonomous fusion activity provides insights into how polymorphisms in clinical isolates confer distinct characteristics.

Xiaohan Chen, Barbara Kropff, Jiawen Li, Heinrich Sticht, Madlen Mollik, Marie Sieger, Fulvia Ferrazzi, Irene Görzer, Michael Mach, Marco Thomas

Abstract read
In one paragraph

Article in mBio, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

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3 · Its place in the literature

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0 citing papers in PubMed.

No citing paper in PubMed yet.

4 · The record

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5 · Who and what money

Authors and funding

10 authors.

Xiaohan Chen *Harald zur Hausen Institute of Virology, Universitätsklinikum Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany.
Barbara Kropff *Harald zur Hausen Institute of Virology, Universitätsklinikum Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany.
Jiawen LiHarald zur Hausen Institute of Virology, Universitätsklinikum Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany.
Heinrich StichtInstitute of Biochemistry, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
Madlen MollikCenter for Virology, Medical University of Vienna, Vienna, Austria.
Marie SiegerDepartment of Nephropathology, Institute of Pathology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
Fulvia FerrazziDepartment of Nephropathology, Institute of Pathology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
Irene GörzerCenter for Virology, Medical University of Vienna, Vienna, Austria.
Michael MachHarald zur Hausen Institute of Virology, Universitätsklinikum Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany.
Marco ThomasHarald zur Hausen Institute of Virology, Universitätsklinikum Erlangen, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany.ORCID 0000-0003-4820-2712

Funding

Deutsche Forschungsgemeinschaft 401821119/GRK2504IZKF, University Hospital of the University of Erlangen-Nürnberg P172
6 · The paper itself

Abstract

Glycoprotein B (gB) serves as the viral fusogen facilitating entry and cell-to-cell spread of human cytomegalovirus (HCMV). Fusion is initiated when gH/gL-containing complexes bind to their receptors, leading to gB's transition from a metastable prefusion to a stable postfusion conformation. We recently demonstrated that substituting or truncating the carboxy-terminal domain of gB renders it intrinsically fusion-competent; however, the precise mechanisms of gB ectodomain reorganization-likely shared by both gH/gL-dependent and -independent fusion processes-remain unclear. In this study, a dual split protein (DSP)-based cell-cell fusion assay was used to assess the gH/gL-independent fusion activities across five major HCMV gB-genotypes (gB1-gB5). Our results show that gB of VR1814 (gB3) exhibits superior autonomous fusion activity compared to TB40/E (gB1) and AD169 (gB2), while gB from C194A (gB4) and UKNEQAS1 (gB5) were fusion-incompetent. Through domain-swapping and site-directed mutagenesis, we identified substitutions that enhance or abrogate fusion and mapped them onto the available pre- and post-fusion structures of gB. Our analysis uncovered a complex network of intra- and inter-domain interactions involving structural domains I, IV, and V of gB, which are crucial for fusion regulation. Functional characterization of gB polymorphisms from clinical HCMV isolates demonstrated opposing impacts, with some variants remaining inactive, while others conferred fusion competence. Collectively, our findings mechanistically elucidate how specific substitutions within the gB ectodomain of particular HCMV strains markedly alter gH/gL-independent fusogenicity. These insights have profound implications for developing diagnostic tools to detect functionally relevant gB polymorphisms and for optimizing vaccine design.IMPORTANCEHuman cytomegalovirus (HCMV) establishes lifelong, predominantly asymptomatic infections but remains a major cause of morbidity and mortality in immunocompromised individuals and newborns. This study elucidates the mechanisms driving the structural reorganization of the gB ectodomain, which likely regulate both gH/gL-independent and -dependent fusion activities across gB-genotypes gB1-gB5. Through a combinatorial

Indexed as

CytomegalovirusPolymorphism, GeneticViral Envelope ProteinsVirus InternalizationCell LineCytomegalovirus InfectionsGenotypeHumansglycoprotein B, SimplexvirusViral Envelope Proteinscell-cell fusiongBgB-genotypesgB polymorphismsgH/gL-independent fusionglycoprotein Bhuman cytomegalovirusmechanism of pre- to post-fusion transition

Identifiers

PMID42439560
PMCPMC13463784

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.