Replicative #fitness of seasonal #influenza A viruses with decreased susceptibility to #baloxavir (J Infect Dis., abstract)

[Source: Journal of Infectious Diseases, full page: (LINK). Abstract, edited.]

Replicative fitness of seasonal influenza A viruses with decreased susceptibility to baloxavir

Anton Chesnokov, Mira C Patel, Vasiliy P Mishin, Juan A De La Cruz, Lori Lollis, Ha T Nguyen, Vivien Dugan, David E Wentworth, Larisa V Gubareva

The Journal of Infectious Diseases, jiz472,

Published: 21 September 2019



Susceptibility of influenza A viruses to baloxavir can be affected by changes at amino acid residue 38 in polymerase acidic (PA) protein. Information on replicative fitness of PA-I38-substituted viruses remains sparse. We demonstrated that substitutions I38L/M/S/T not only had a differential effect on baloxavir susceptibility (9- to 116-fold), but also on in vitro replicative fitness. While I38L conferred undiminished growth, other substitutions led to mild attenuation. In a ferret model, control viruses outcompeted those carrying I38M or I38T substitutions, although their advantage was limited. These findings offer insights into the attributes of baloxavir resistant viruses needed for informed risk assessment.

Cap-dependent endonuclease inhibitor, replicative fitness, polymerase acidic protein, influenza, drug resistance, ferret, baloxavir acid, antiviral

Issue Section: Brief Report

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Author notes

These authors contributed equally to this article and share first authorship

Published by Oxford University Press for the Infectious Diseases Society of America 2019. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Keywords: Influenza A; Antivirals; Drugs Resistance; Baloxavir.


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Giuseppe Michieli

I am an Italian blogger, active since 2005 with main focus on emerging infectious diseases such as avian influenza, SARS, antibiotics resistance, and many other global Health issues. Other fields of interest are: climate change, global warming, geological and biological sciences. My activity consists mainly in collection and analysis of news, public services updates, confronting sources and making decision about what are the 'signals' of an impending crisis (an outbreak, for example). When a signal is detected, I follow traces during the entire course of an event. I started in 2005 my blog ''A TIME'S MEMORY'', now with more than 40,000 posts and 3 millions of web interactions. Subsequently I added an Italian Language blog, then discontinued because of very low traffic and interest. I contributed for seven years to a public forum ( in the midst of the Ebola epidemic in West Africa in 2014, I left the site to continue alone my data tracking job.