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Structure, maturation and cell entry mechanisms of ranavirus virions


The long-term goal of this proposal is to understand the molecular mechanisms of the replication cycle of
nucleocytoplasmic large DNA viruses that attracted attention after the discovery of the giant Mimivirus a
decade ago. Here, we focus on ranaviruses from the family Iridoviridae that have caused large economic
losses in Europe and Asia and threaten wildlife biodiversity worldwide. The ranavirus disease has therefore
been listed by the World Organization for Animal Health. Ranaviruses have a unique replication cycle that
leads to two coexisting forms of infectious particles, naked capsids and enveloped virions, each with
different mechanisms of cell egress and cell entry. Additionally, the proteinaceous capsid contains an
internal membrane that presumably assists to assembly of a large DNA-free icosahedral shell. This shell
is subsequently filled by the viral genome and transforms into the mature capsid by a headful packaging mechanism that is also used by some dsDNA bacteriophages. We aim to characterize the structural and mechanistic features of ranavirus
assembly, maturation and cell entry by combination of cryo-electron microscopy and tomography with other
complementary techniques. The novelty in our plan is application of cryo-FIB micromachining and cryo-electron
tomography to visualize the intracellular steps of the ranavirus replication cycle in 3D at native
conditions. The three objectives of this research project are to: (i) identify the structural basis of subunit
recognition that guides assembly of large icosahedral capsids of type ranaviruses and elucidate the function
of the internal membrane in this process, (ii) determine the conformational changes that accompany
maturation of ranavirus capsids and regulate the headful packaging of the dsDNA genome, and (iii) ascertain
the mechanisms of cell entry by the naked capsids and enveloped ranavirus virions.

Call for proposal

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Funding Scheme

MC-CIG - Support for training and career development of researcher (CIG)


Masarykova univerzita
Zerotinovo Namesti 9
60177 Brno Stred
Activity type
Higher or Secondary Education Establishments
EU contribution
€ 100 000
Administrative Contact
Veronika Papouskova (Dr.)