tetano
Editor, Senior Moderator
J Virol. 2014 May 14. pii: JVI.03178-13. [Epub ahead of print]
Single domain antibodies targeting neuraminidase protect against an H5N1 influenza virus challenge.
Cardoso FM1, Iba?ez LI1, Van den Hoecke S1, De Baets S1, Smet A1, Roose K1, Schepens B1, Descamps FJ1, Fiers W1, Muyldermans S2, Depicker A3, Saelens X4.
Author information
Abstract
Influenza virus neuraminidase (NA) is an interesting target of small-molecule antiviral drugs. We isolated a set of H5N1 NA-specific single domain antibodies (N1-VHHm) and evaluated their in vitro and in vivo antiviral potential. Two of them inhibited NA activity and in vitro replication of clade 1 and 2 H5N1 viruses. We then generated bivalent derivatives of N1-VHHm by two methods. First we made N1-VHHb by genetically joining two N1-VHHm moieties by a flexible linker. Second, bivalent N1-VHH-Fc proteins were obtained by genetic fusion of the N1-VHHm moiety the crystallizable region of mouse IgG2a (Fc). The in vitro antiviral potency against H5N1 of both bivalent N1-VHHb formats was 30- to 240-fold higher than their monovalent counterparts, with IC50 values in the low nanomolar range. Moreover, single-dose prophylactic treatment with bivalent N1-VHHb or N1-VHH-Fc protected BALB/c mice against a lethal challenge with H5N1 virus, including an Oseltamivir-resistant H5N1 variant. Surprisingly, also an N1-VHH-Fc fusion without in vitro NA inhibitory or antiviral activity protected mice against H5N1 challenge. Virus escape selection experiments indicated that one amino acid residue close to the catalytic site is required for N1-VHHm binding. We conclude that single domain antibodies directed against influenza NA protect against H5N1 virus infection, and when engineered with a conventional Fc domain, they can do so in the absence of detectable NA inhibitory activity.
IMPORTANCE:
Highly pathogenic H5N1 viruses are a zoonotic threat. Outbreaks of bird flu caused by these viruses occur in many parts of the world, are associated with tremendous economic loss and these viruses can cause very severe disease in human. In such cases, small molecule inhibitors of the viral neuraminidase are among the few treatment options for patients. However treatment with such drugs often results in the emergence of resistant viruses. Here we show that single domain antibody fragments that are specific for NA can bind and inhibit H5N1 viruses in vitro and can protect laboratory mice against challenge with an H5N1 virus, including an oseltamivir-resistant virus. In addition, plant-produced VHH fused to a conventional Fc domain, can protect in vivo even in the absence of NA inhibitory activity. Thus, NA of influenza virus can be effectively targeted by single domain antibody fragments, which are amenable to further engineering.
Copyright ? 2014, American Society for Microbiology. All Rights Reserved.
PMID:
24829341
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/24829341
Single domain antibodies targeting neuraminidase protect against an H5N1 influenza virus challenge.
Cardoso FM1, Iba?ez LI1, Van den Hoecke S1, De Baets S1, Smet A1, Roose K1, Schepens B1, Descamps FJ1, Fiers W1, Muyldermans S2, Depicker A3, Saelens X4.
Author information
Abstract
Influenza virus neuraminidase (NA) is an interesting target of small-molecule antiviral drugs. We isolated a set of H5N1 NA-specific single domain antibodies (N1-VHHm) and evaluated their in vitro and in vivo antiviral potential. Two of them inhibited NA activity and in vitro replication of clade 1 and 2 H5N1 viruses. We then generated bivalent derivatives of N1-VHHm by two methods. First we made N1-VHHb by genetically joining two N1-VHHm moieties by a flexible linker. Second, bivalent N1-VHH-Fc proteins were obtained by genetic fusion of the N1-VHHm moiety the crystallizable region of mouse IgG2a (Fc). The in vitro antiviral potency against H5N1 of both bivalent N1-VHHb formats was 30- to 240-fold higher than their monovalent counterparts, with IC50 values in the low nanomolar range. Moreover, single-dose prophylactic treatment with bivalent N1-VHHb or N1-VHH-Fc protected BALB/c mice against a lethal challenge with H5N1 virus, including an Oseltamivir-resistant H5N1 variant. Surprisingly, also an N1-VHH-Fc fusion without in vitro NA inhibitory or antiviral activity protected mice against H5N1 challenge. Virus escape selection experiments indicated that one amino acid residue close to the catalytic site is required for N1-VHHm binding. We conclude that single domain antibodies directed against influenza NA protect against H5N1 virus infection, and when engineered with a conventional Fc domain, they can do so in the absence of detectable NA inhibitory activity.
IMPORTANCE:
Highly pathogenic H5N1 viruses are a zoonotic threat. Outbreaks of bird flu caused by these viruses occur in many parts of the world, are associated with tremendous economic loss and these viruses can cause very severe disease in human. In such cases, small molecule inhibitors of the viral neuraminidase are among the few treatment options for patients. However treatment with such drugs often results in the emergence of resistant viruses. Here we show that single domain antibody fragments that are specific for NA can bind and inhibit H5N1 viruses in vitro and can protect laboratory mice against challenge with an H5N1 virus, including an oseltamivir-resistant virus. In addition, plant-produced VHH fused to a conventional Fc domain, can protect in vivo even in the absence of NA inhibitory activity. Thus, NA of influenza virus can be effectively targeted by single domain antibody fragments, which are amenable to further engineering.
Copyright ? 2014, American Society for Microbiology. All Rights Reserved.
PMID:
24829341
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/24829341