establishment-quantification-de-novo-lytic-infection-cell-free-kaposi

Establishment and Quantification of <em>De Novo</em> Lytic Infection by Cell-free Kaposi's Sarcoma-Associated Herpesvirus

Kaposi's sarcoma-associated herpesvirus (KSHV), a gammaherpesvirus implicated in multiple human malignancies, can undergo lytic replication during primary ...

The Wistar Institute

Mitochondrial dynamics are pivotal for host immune responses upon infection, yet how viruses manipulate these processes to impair host defence and enhance viral fitness remains unclear. Here we show that Kaposi's sarcoma-associated herpesvirus (KSHV), an oncogenic virus also known as human herpesvirus 8, encodes Bcl-2 (vBcl-2), which reprogrammes mitochondrial architecture. It binds with NM23-H2, a host nucleoside diphosphate (NDP) kinase, to stimulate GTP loading of the dynamin-related protein (DRP1) GTPase, which triggers mitochondrial fission, inhibits mitochondrial antiviral signalling protein (MAVS) aggregation and impairs interferon responses in cell lines. An NM23-H2-binding-defective vBcl-2 mutant fails to evoke fission, leading to defective virion assembly due to activated MAVS-IFN signalling. Notably, we identify two key interferon-stimulated genes restricting vBcl-2-dependent virion morphogenesis. Using a high-throughput drug screening, we discover an inhibitor targeting vBcl-2-NM23-H2 interaction that blocks virion production in vitro. Our study identifies a mechanism in which KSHV manipulates mitochondrial dynamics to allow for virus assembly and shows that targeting the virus-mitochondria interface represents a potential therapeutic strategy.

Kaposi's sarcoma-associated herpesvirus induces mitochondrial fission to evade host immune responses and promote viral production.

Viral subversion of macroautophagy/autophagy is a well-established immune evasion strategy, with BCL2 homologs from γ-herpesviruses serving as prototypical inhibitors through BECN1 (beclin 1) sequestration. Yet the full spectrum of their functions remains incompletely understood. In our recent study, we uncovered a non-canonical role for the Kaposi's sarcoma-associated herpesvirus (KSHV)-encoded BCL2 homolog (vBCL2) during late lytic replication. Unexpectedly, vBCL2 hijacks the host NDP kinase NME2/NM23-H2 to activate the mitochondrial fission GTPase DNM1L/DRP1, promoting mitochondrial fragmentation. This organelle remodeling dismantles MAVS-mediated antiviral signaling and facilitates virion assembly. A vBCL2 mutant unable to bind NME2 fails to induce fission or complete the viral lifecycle. These findings provide a long-sought answer to why vBCL2 is indispensable during lytic infection, and uncover a new immune evasion strategy centered on mitochondrial control. Our work expands the current view of virus-organelle interactions beyond canonical autophagy control and offers new targets for therapeutic intervention.

Article	Year
Kaposi's sarcoma-associated herpesvirus induces mitochondrial fission to evade host immune responses and promote viral production. Nature microbiology\| PubMed ID: 40404827	2025
A classical anti-autophagic viral protein reshapes mitochondria for immune evasion. Autophagy\| PubMed ID: 40574281	2025

Qing Zhu

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