Thurmond, S. | Search bioRxiv

bioRxiv2025

Anellovirus protein coded by ORF2/3 recruits host cell replication andhomologous recombination machinery during replication

Anelloviridae is a family of single-stranded DNA viruses that are thought to be non-pathogenic and commensal. Despite their ubiquitous presence in human populations, little is known about the anellovirus mechanism of replication in host cells. We identified the protein coded by ORF2/3 as necessary and sufficient to initiate replication from the minimal origin of replication for viruses of both the Beta- and Alphatorquevirus genera. Supporting this observation, we identified components of the polymerase alpha and BTR complexes as interacting with the viral replication initiation protein (Rip) during DNA replication, suggesting a recombination-dependent mechanism of replication that uses host cell machinery to mediate dissolution of replication intermediates. Furthermore, we mapped a 92-bp minimal origin of replication sequence for the Betatorquevirus genus comprised of an AT-rich stretch and a portion of the GC-rich region. Altogether, this study provides a first insight into the mechanism by which anelloviruses manipulate host cell machinery to facilitate viral genome replication and represents a significant step forward in understanding the complex processes underlying anellovirus replication and persistent infection of these important commensal viruses.

molecular biology↗

bioRxiv2024

A novel functional gene delivery platform based on a commensal human anellovirus demonstrates transduction in multiple tissue types

Anelloviridae is a family of non-enveloped viruses with negative-sense, circular, single-stranded deoxyribonucleic acid (ssDNA) genomes that infect vertebrates and are a ubiquitous component of the human virome. Human anelloviruses evade induction of humoral immune responses and appear to be non-pathogenic. These properties, in conjunction with their enormous genomic diversity and wide tissue distribution, make anelloviruses compelling candidates as vectors for next-generation genetic medicines. Here we report the first gene delivery vector system based on a human commensal virus. This Anellovector is based on a virus of the Betatorquevirus genus. Production is enabled by the development of the Self-Amplifying Trans-complementation of a Universal Recombinant aNellovector (SATURN) system, which relies on a self-replicating plasmid to provide viral proteins in trans that drive replication and capsid-dependent packaging of vector genomes. The SATURN system also utilizes a Cre-lox-based recombination mechanism to generate single unit-sized circular genomes inside the MOLT-4 production cell line. We demonstrate that the SATURN system can package a vector genome from a single betatorquevirus with capsids from multiple betatorquevirus species, supporting the feasibility of establishing a novel vector platform that takes advantage of the remarkable diversity of anelloviruses. The Anellovector demonstrated function in vitro in retinal pigment epithelial (RPE) cells. The Anellovector also demonstrated durable in vivo function in the mouse eye for 9 months after subretinal administration, and achieved comparable gene expression to dose-matched adeno-associated virus 9 (AAV9) when transduced by the intracerebroventricular (ICV) route of administration. To our knowledge, this is the first report of a functional anellovirus-based gene therapy vector. Anellovectors have great potential to deliver safe, redosable, and potent therapeutics, helping to expand the reach of programmable medicines.

bioengineering↗