Evolution of highly pathogenic H5N1 influenza A virus in the central nervous system of ferrets

Jurre Y. Siegers, Lucas Ferreri, Dirk Eggink, Edwin J.B. Veldhuis Kroeze, Aartjan J.W. Te Velthuis, Marco van de Bildt, Lonneke Leijten, Peter van Run, Dennis de Meulder, Theo Bestebroer, Mathilde Richard, Thijs Kuiken, Anice C. Lowen, Sander Herfst, Debby van Riel

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Central nervous system (CNS) disease is the most common extra-respiratory tract complication of influenza A virus infections in humans. Remarkably, zoonotic highly pathogenic avian influenza (HPAI) H5N1 virus infections are more often associated with CNS disease than infections with seasonal influenza viruses. Evolution of avian influenza viruses has been extensively studied in the context of respiratory infections, but evolutionary processes in CNS infections remain poorly understood. We have previously observed that the ability of HPAI A/Indonesia/5/2005 (H5N1) virus to replicate in and spread throughout the CNS varies widely between individual ferrets. Based on these observations, we sought to understand the impact of entrance into and replication within the CNS on the evolutionary dynamics of virus populations. First, we identified and characterized three substitutions-PB1 E177G and A652T and NP I119M - detected in the CNS of a ferret infected with influenza A/Indonesia/5/2005 (H5N1) virus that developed a severe meningo-encephalitis. We found that some of these substitutions, individually or collectively, resulted in increased polymerase activity in vitro. Nevertheless, in vivo, the virus bearing the CNS-associated mutations retained its capacity to infect the CNS but showed reduced dispersion to other anatomical sites. Analyses of viral diversity in the nasal turbinate and olfactory bulb revealed the lack of a genetic bottleneck acting on virus populations accessing the CNS via this route. Furthermore, virus populations bearing the CNS-associated mutations showed signs of positive selection in the brainstem. These features of dispersion to the CNS are consistent with the action of selective processes, underlining the potential for H5N1 viruses to adapt to the CNS.

Original languageEnglish
Article numbere1011214
JournalPLoS Pathogens
Issue number3
Publication statusPublished - 10 Mar 2023

Bibliographical note

Funding: DvR is supported by the Netherlands
Organization for Scientific Research (VIDI
91718308) and an EUR fellowship. This work was
funded in part by R01 AI154894 to ACL and NIH/
NIAID contract HHSN272201400008C to MR and
SH. AtV is supported by NIH/NIAID (grants DP2
AI175474-01 and R01 AI170520), and Wellcome
Trust (grant 206579/Z/17/Z). The funders had no
role in study design, data collection and analysis,
decision to publish, or preparation of the

Publisher Copyright:
Copyright: © 2023 Siegers et al.


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