Triple combination therapy of favipiravir plus two monoclonal antibodies eradicates influenza virus from nude mice

Prolonged treatment of immunocompromised influenza patients with viral neuraminidase (NA) inhibitors is required, because the immune system of such patients fails to eradicate the viruses. Here, we attempted to eradicate influenza virus from the respiratory organs of nude mice, which is a model of immunocompromised hosts, by using combination therapy of the viral polymerase inhibitor favipiravir and monoclonal antibodies (mAbs) against the receptor-binding site (RBS) and stem of viral hemagglutinin (HA). Although monotherapy or combination therapy of two antivirals (two mAbs or favipiravir plus a mAb) suppressed virus replication, they failed to eradicate viruses from nude mice. In contrast, the triple combination therapy of favipiravir plus anti-Stem and anti-RBS mAbs completely stopped virus replication in nude mice, resulting in virus clearance. Triple combination approaches should be considered for the treatment of human immunocompromised patients with severe influenza.

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Yoshihiro Kawaoka and Seiya Yamayoshi
Dec 24, 2019 Sequence data were collected using ABI Prism 3130xl Genetic Analyzer data collection software (version 3.0).
GENETYX genetic information processing software (version 13) was used for sequence alignment. ATGC sequence assembly software (version 7.0) was used for sequence assemblies. Graphpad Prism (version 5) was used for calculating IC50 values and statistical analysis. Structural analysis was performed by using the PyMOL molecular graphics system.
All data analyzed during this study are included in this article. The datasets generated and analyzed during the current study are available from the corresponding author on reasonable request.

nature research | reporting summary
October 2018

Life sciences study design
All studies must disclose on these points even when the disclosure is negative. No data were excluded.
In vitro assays were performed in 2 independent experiments. The in vivo protection test was performed with four mice per experimental group. All available data are included in the manuscript.
No method of randomization was used to determine how the animals were allocated to the experimental groups and processed in this study.
No blinding was performed.
All human antibodies used in this study were made recombinantly by cloning antibody heavy and light chains into mammalian expression vectors. Antibodies were produced in mammalian cells The DNA fingerprinting method was used to show that the MDCK cells have the same origin as the MDCK (CCL-34) obtained from ATCC.
All cell lines were regularly tested for mycoplasma contamination by using PCR and were confirmed to be mycoplasma-free.
No commonly misidentified cell lines were used.
Five-week-old female BALB/c-nu/nu mice (Japan SLC) were used in the study. n.a. n.a.