The final cut: how giant viruses of protists are released from their hosts’ cells

Abstract

Viruses are the most abundant biological entities on Earth, with an estimated 10³¹ viruses in the biosphere. These particles serve as the crucial link between viral replication cycles in different host cells, employing a variety of release mechanisms, such as cell lysis, exocytosis, and budding. Among the diverse viral groups, giant viruses have garnered significant scientific interest due to their complex particles and genomes. Giant viruses may infect amoebae and other unicellular protists, exhibiting remarkable variation in size, shape, and symmetry. They belong to the realm Varidnaviria, kingdom Bamfordvirae, and phylum Nucleocytoviricota. This review examines the diverse viral release strategies employed by giant viruses, highlighting the mechanisms they use to exit host cells. These include the induction of cell lysis, vesicle formation, and exocytosis, which vary not only between different species but also within individual viral groups. The diversity of release mechanisms reflects the complex evolutionary adaptations of giant viruses, providing information about their biology and life cycles.