Cross-Reactive Fc-Fused Single-Domain Antibodies to Hemagglutinin Stem Region Protect Mice from Group 1 Influenza a Virus Infection

Abstract

The continued evolution of influenza viruses reduces the effectiveness of vaccination and antiviral drugs. The identification of novel and universal agents for influenza prophylaxis and treatment is an urgent need. We have previously described two potent single-domain antibodies (VHH), G2.3 and H1.2, which bind to the stem domain of hemagglutinin and efficiently neutralize H1N1 and H5N2 influenza viruses in vivo. In this study, we modified these VHHs with Fc-fragment to enhance their antiviral activity. Reformatting of G2.3 into bivalent Fc-fusion molecule increased its in vitro neutralizing activity against H1N1 and H2N3 viruses up to 80-fold and, moreover, resulted in obtaining the ability to neutralize H5N2 and H9N2 subtypes. We demonstrated that a dose as low as 0.6 mg/kg of G2.3-Fc or H1.2-Fc administered systemically or locally before infection could protect mice from lethal challenges with both H1N1 and H5N2 viruses. Furthermore, G2.3-Fc reduced the lung viral load to an undetectable level. Both VHH-Fc antibodies showed in vivo therapeutic efficacy when delivered via systemic or local route. The findings support G2.3-Fc as a potential therapeutic agent for both prophylaxis and therapy of Group 1 influenza A infection.

rAAV expressing recombinant antibody for emergency prevention and long-term prophylaxis of COVID-19

“…The proposed recombinant Fc-fusion single-domain antibody variant may be more effective than a monoclonal antibody due to the presence of long CDR3 loops enabling their binding to conservative hard-to-reach epitopes of viral antigens. Thus, such recombinant antibodies can have a wide range of neutralizing activity against various variants of the influenza virus, Ebola virus and SARS-CoV-2 ( 16 , 17 , 21 ). Thus, the emergence of antibody-resistant virus strains is less likely.…”

“…There is evidence demonstrating the efficacy of this approach for induction of prolonged protection against Ebola, Marburg and influenza viral diseases as well as botulinum neurotoxin intoxication ( 11 – 15 ). The choice of rAAV was dictated by their ability to transduce a wide spectrum of cellular targets, low immunogenicity, safety and prolonged persistence in the body as episome ( 16 ).…”

Next generation single-domain antibodies against respiratory zoonotic RNA viruses

“…However, various studies demonstrate that the efficiency of intranasal administration extends to higher valency constructs ( Tillib et al, 2013 ; Huo et al, 2021 ; Nambulli et al, 2021 ; Wu et al, 2021 ). Additionally, an Fc-fused sdAb has been succesfully aerosolized ( Voronina et al, 2022 ), and even a large decameric sdAb construct could be nebulized resulting in effective in vivo protection ( Liu et al, 2023a ). These observations align with an even larger variety of studies showcasing successful protection against respiratory CoVs and influenza viruses through intranasal sdAb administration ( table 1 ) ( Tillib et al, 2013 ; Cardoso et al, 2014 ; Huo et al, 2021 ; Nambulli et al, 2021 ; Wu et al, 2021 ; Voronina et al, 2022 ; Liu et al, 2023a ).…”

“…Additionally, an Fc-fused sdAb has been succesfully aerosolized ( Voronina et al, 2022 ), and even a large decameric sdAb construct could be nebulized resulting in effective in vivo protection ( Liu et al, 2023a ). These observations align with an even larger variety of studies showcasing successful protection against respiratory CoVs and influenza viruses through intranasal sdAb administration ( table 1 ) ( Tillib et al, 2013 ; Cardoso et al, 2014 ; Huo et al, 2021 ; Nambulli et al, 2021 ; Wu et al, 2021 ; Voronina et al, 2022 ; Liu et al, 2023a ). Some studies even emphasize additional benefits compared to intraperitoneal or intravenous administration.…”

“…Intranasal delivery can also result in pathological benefits as exemplified by a study where they found alleviated lung lesions after intranasal sdAb administration ( Liu et al, 2023a ). In some cases both intranasal and intraperitoneal sdAb administration results in full in vivo protection, where the advantage of intranasal administration is the requirement of a lower dose ( Voronina et al, 2022 ).…”