Point mutations in the glycoprotein ectodomain of field rabies viruses mediate cell culture adaptation through improved virus release in a host cell dependent and independent manner

Sabine Nitschel, Luca M. Zaeck, Madlin Potratz, Tobias Nolden, Verenate Kamp, Kati Franzke, Dirk Höper, Florian Pfaff, Stefan Finke*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

5 Citations (Scopus)
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Abstract

Molecular details of field rabies virus (RABV) adaptation to cell culture replication are insufficiently understood. A better understanding of adaptation may not only reveal requirements for efficient RABV replication in cell lines, but may also provide novel insights into RABV biology and adaptation-related loss of virulence and pathogenicity. Using two recombinant field rabies virus clones (rRABV Dog and rRABV Fox), we performed virus passages in three different cell lines to identify cell culture adaptive mutations. Ten passages were sufficient for the acquisition of adaptive mutations in the glycoprotein G and in the C-terminus of phosphoprotein P. Apart from the insertion of a glycosylation sequon via the mutation D247N in either virus, both acquired additional and cell line-specific mutations after passages on BHK (K425N) and MDCK-II (R346S or R350G) cells. As determined by virus replication kinetics, complementation, and immunofluorescence analysis, the major bottleneck in cell culture replication was the intracellular accumulation of field virus G protein, which was overcome after the acquisition of the adaptive mutations. Our data indicate that limited release of extracellular infectious virus at the plasma membrane is a defined characteristic of highly virulent field rabies viruses and we hypothesize that the observed suboptimal release of infectious virions is due to the inverse correlation of virus release and virulence in vivo.

Original languageEnglish
Article number1989
JournalViruses
Volume13
Issue number10
DOIs
Publication statusPublished - 3 Oct 2021
Externally publishedYes

Bibliographical note

Funding Information:
This work was funded by an intramural collaborative research grant on Lyssaviruses at the Friedrich-Loeffler-Institute (Ri-0372) to S.F.We thank Dietlind Kretzschmar and Angela Hillner for technical assistance. Figure 1 was created with Biorender.com.

Publisher Copyright:
© 2021 by the author. Licensee MDPI, Basel, Switzerland.

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