Novel Pandemic Influenza A(H1N1) Viruses Are Potently Inhibited by DAS181, a Sialidase Fusion Protein

Abstract

BackgroundThe recent emergence of a novel pandemic influenza A(H1N1) strain in humans exemplifies the rapid and unpredictable nature of influenza virus evolution and the need for effective therapeutics and vaccines to control such outbreaks. However, resistance to antivirals can be a formidable problem as evidenced by the currently widespread oseltamivir- and adamantane-resistant seasonal influenza A viruses (IFV). Additional antiviral approaches with novel mechanisms of action are needed to combat novel and resistant influenza strains. DAS181 (Fludase™) is a sialidase fusion protein in early clinical development with in vitro and in vivo preclinical activity against a variety of seasonal influenza strains and highly pathogenic avian influenza strains (A/H5N1). Here, we use in vitro, ex vivo, and in vivo models to evaluate the activity of DAS181 against several pandemic influenza A(H1N1) viruses.Methods and FindingsThe activity of DAS181 against several pandemic influenza A(H1N1) virus isolates was examined in MDCK cells, differentiated primary human respiratory tract culture, ex-vivo human bronchi tissue and mice. DAS181 efficiently inhibited viral replication in each of these models and against all tested pandemic influenza A(H1N1) strains. DAS181 treatment also protected mice from pandemic influenza A(H1N1)-induced pathogenesis. Furthermore, DAS181 antiviral activity against pandemic influenza A(H1N1) strains was comparable to that observed against seasonal influenza virus including the H274Y oseltamivir-resistant influenza virus.ConclusionsThe sialidase fusion protein DAS181 exhibits potent inhibitory activity against pandemic influenza A(H1N1) viruses. As inhibition was also observed with oseltamivir-resistant IFV (H274Y), DAS181 may be active against the antigenically novel pandemic influenza A(H1N1) virus should it acquire the H274Y mutation. Based on these and previous results demonstrating DAS181 broad-spectrum anti-IFV activity, DAS181 represents a potential therapeutic agent for prevention and treatment of infections by both emerging and seasonal strains of IFV.

Prevention of influenza by targeting host receptors using engineered proteins

“…DAS181 (Fludase) is a biologic formed by linking the catalytic domain of the promiscuous sialidase from Actinomyces viscosus to the epithelium-anchoring domain of human amphiregulin (28). DAS181 removes sialic acids from the epithelial surface and, when administered intranasally, protects against infection with avian H5N1 and pandemic 2009 H1N1 viruses in mice (29,30). DAS181 is currently in Phase II development (27).…”

Antiviral Susceptibility of Variant Influenza A(H3N2)v Viruses Isolated in the United States from 2011 to 2013

“…The working solutions of nitazoxanide, favipiravir, and ribavirin were prepared at the time of each experiment in virus growth medium (Dulbecco's modified eagles medium [DMEM]; Gibco, Carlsbad, CA) supplemented with 100 IU penicillin/ streptomycin (Gibco, Carlsbad, CA), 0.5% bovine serum albumin (BSA; Gibco, Carlsbad, CA), and 2 g/ml L-tosylamide-2-phenylethyl chloromethyl ketone (TPCK)-treated trypsin (Sigma-Aldrich, St. Louis, MO). The stock of fludase was stored at Ϫ80°C, and dilutions were made in EDB-BSA buffer (10 mM sodium acetate buffer, pH 6.0, supplemented with 0.1 M NaCl, 10 mM CaCl 2 , 0.5 mM MgCl 2 , and 0.5% BSA) prior to testing in cell culture (16).…”

“…The reduction in the number of focus-forming units (FFU) was determined as described previously (16). Briefly, cell monolayers were pretreated for 2 h with fludase at concentrations ranging from 0.02 M to 4 M. Any unbound fludase was removed by washing cells three times with phosphate-buffered saline (PBS; Gibco, Grand Island, NY).…”

“…Virus inoculum at a multiplicity of infection (MOI) of 0.0001 to 0.0003 was added, and cells were washed again after 1 h of incubation at 37°C with 5% CO 2 . Virus growth medium was added to the monolayers, and cells were incubated for 24 h, at which point cell monolayers were fixed and immunostained; FFU were counted under a microscope (16).…”

Pandemic Influenza A H1N1 (2009) Virus: Lessons from the Past and Implications for the Future

“…A new pyrazole-based compound BPR1P0034, which acts during viral uncoating or viral RNA import into the nucleus has shown promising results as an antiviral drug [29]. DAS181 is a sialidase fusion protein which in early clinical development with in vitro and in vivo preclinical activity against a variety of seasonal influenza strains and highly pathogenic avian influenza strains (A/H5N1), has also shown satisfactory results with the recent pandemic H1N1 strain [33].…”