OP7, a novel influenza A virus defective interfering particle: production, purification, and animal experiments demonstrating antiviral potential

Abstract

The novel influenza A virus (IAV) defective interfering particle “OP7” inhibits IAV replication in a co-infection and was previously suggested as a promising antiviral agent. Here, we report a batch-mode cell culture-based production process for OP7. In the present study, a seed virus containing standard virus (STV) and OP7 was used. The yield of OP7 strongly depended on the production multiplicity of infection. To inactivate infectious STV in the OP7 material, which may cause harm in a potential application, UV irradiation was used. The efficacy of OP7 in this material was preserved, as shown by an in vitro interference assay. Next, steric exclusion chromatography was used to purify and to concentrate (~ 13-fold) the UV-treated material. Finally, administration of produced OP7 material in mice did not show any toxic effects. Furthermore, all mice infected with a lethal dose of IAV survived the infection upon OP7 co-treatment. Thus, the feasibility of a production workflow for OP7 and its potential for antiviral treatment was demonstrated. Key points • OP7 efficacy strongly depended on the multiplicity of infection used for production • Purification by steric exclusion chromatography increased OP7 efficacy • OP7-treated mice were protected against a lethal infection with IAV

Semi-continuous propagation of influenza A virus and its defective interfering particles: analyzing the dynamic competition to select candidates for antiviral therapy

“…In a follow-up study, DIPs harboring the most competitive DI vRNAs identified in this study will be produced using cell lines stably expressing the missing viral proteins to complement the defect of these DIPs (Bdeir et al, 2019). And, further investigations will be performed to characterize these candidates with respect to their interfering efficacy and options for their use in antiviral therapy (Hein et al, 2020; Kupke et al, 2019).…”

“…Furthermore, interference was shown for the packaging step, as DI vRNAs selectively outcompeted FL vRNAs (Duhaut and McCauley, 1996; Odagiri and Tashiro, 1997). Notably, in mouse and ferret models, the administration of DIPs showed a pronounced antiviral effect against IAV (Dimmock et al, 2012; Dimmock et al, 2008; Hein et al, 2020; Huo et al, 2020; Zhao et al, 2018).…”

Cell culture-based production of defective interfering influenza A virus particles in perfusion mode using an alternating tangential flow filtration system

“…Furthermore, it required the inactivation of the infectious STV after harvesting, for example by UV irradiation. This UV irradiation also inactivated parts of the produced DIPs and therefore decreased the antiviral potency of final preparations used in animal trials (Hein et al 2021b). To overcome this limitation, a method for production of purely clonal DIP populations, devoid of STV and other DIPs, was developed (Bdeir et al 2019).…”

Antiviral activity of influenza A virus defective interfering particles against SARS-CoV-2 replicationin vitrothrough stimulation of innate immunity

“…Furthermore, DIPs suppress and interfere specifically with homologous viral replication in a coinfection scenario, a process known as replication interference. As a result, administration of IAV DIPs to mice resulted in full protection against an otherwise lethal IAV infection (Dimmock et al, 2008, Huo et al, 2020b, Hein et al, 2021c, Hein et al, 2021a. In the ferret model, treatment of IAV-infected animals resulted in a reduced severity of disease pathogenesis (Dimmock et al, 2012).…”

“…To prevent this, we wondered whether IAV DIPs would be able to suppress SARS-CoV-2 replication through their ability to stimulate a physiological IFN response in target cells. To test this, we produced two promising candidate DIPs, a prototypic, wellcharacterized conventional IAV DIP "DI244" (Dimmock and Easton, 2014), and a novel type of IAV DIP "OP7", that contains point mutations instead of a large internal deletion in the genome (Kupke et al, 2019), using a cell culture-based production process (Hein et al, 2021c, Hein et al, 2021a, Hein et al, 2021b.…”