Recombinant Antibodies Against Influenza A Virus Subtype H5N1

The avian influenza A virus subtype H5N1 is a public health threat with the potential to cause disastrous effects to agricultural poultry flocks as well as serious illness and death in humans. Understanding its ecology, pathology and transmission is crucial to prevent these risks.

Absolute Antibody is committed to helping research on influenza A virus subtype H5N1. Our catalog offers a wide range of antibodies with different antigen specificities, cross-reactivities, and applications to support our customers in finding the most suitable reagents for their research.

H5N1 subtype

The natural reservoirs of influenza A virus are aquatic birds, in which the virus fully adapted to its host causing no signs of disease (Webster et al., 1992). The virus can be transmitted to domesticated birds, such as chickens and turkeys, through direct contact with infected waterfowl or infected poultry. In these hosts, the pathology of the disease can be extremely severe, especially with certain subtypes, such as H5N1, causing outbreaks of fowl plague. Further, this subtype has also been associated with human infections as monitored by the WHO. Currently, H5N1 subtype is not efficiently transmitted from person to person. However, because the virus undergoes continuous antigenic alterations it is possible that the strain becomes adapted to human horizontal transmission, causing a widespread outbreak of influenza infection (Thomas et al., 2007).

Fig 1. ELISA activity data of antibodies FC41 (Ab00149, green line), FLD84 (Ab00247, brown line), FLD127 (Ab00248, red line), FLD21 (Ab00250, blue line), H5.3 (Ab00798, purple line), T1-3B (Ab01106, yellow line), CR6261 (Ab02199, grey line) and an isotype control (Ab00102, orange line) binding to Influenza A HA [A/Hong Kong/483/97 (H5N1)].

Influenza A virus falls in the family Orthomyxoviridae, which also includes influenza B and influenza C viruses. Influenza A is a single-stranded, negative-sense ribonucleic acid (RNA) virus with a segmented genome. There are eight RNA segments in the influenza A virus containing genome-encoding 11 viral proteins: the polymerase proteins (PB1, PB2, PA, PB1-F2), nucleocapsid proteins, hemagglutinin (HA), neuraminidase (NA), matrix proteins (M1, M2), and non-structural proteins (NS1, NS2) (Dong et al., 2013).

Further subtyping of influenza A viruses is based on the antigenic properties of the envelope surface proteins HA and NA. Currently eighteen known HA subtypes (H1 to H18) and eleven NA subtypes (N1 to N11) have been isolated (Nuñez et al., 2019). HA plays a crucial role during virus entry into the cell to initiate infection and is thus a determinant of host range. HA binds to the sialic acid on the surface of the host cells. After binding, the virus enters the cell through receptor-mediated endocytosis. The HA ectodomain is composed of two regions, a globular head region and a stem region. The globular head contains the receptor-binding cavity as well as most of the antigenic sites of the molecule and is subject to continuous antigenic drift, while the structure of the stem region is more conserved. NA catalyzes the cleavage of virus particles from the sialic acid sites on the host cell, thus facilitating the spreading of the virus within the host. Similarly to HA, NA is highly mutable and undergoes antigenic drift (de Jong et al., 2006). The globular heads of HA and NA are the major target of neutralizing antibodies, as inhibiting the virus binding to target cells and spreading would reduce viral infection and disease.

Recombinant Engineered Antibodies

Fig 2. ELISA activity data of antibodies HA (Ab00151, green line), FE17 (Ab00150, red line), FB75 (Ab00148, blue line), 8H5 (Ab02100, black line), AV.C4 (Ab02203, pink line), AV.G4 (Ab02205, purple line), 310-18A3 (Ab02849, yellow line) and an isotype control (Ab00102, orange line) binding to Influenza A HA [A/Hong Kong/483/97 (H5N1)].

Absolute Antibody recombinantly produces anti-influenza A H5N1 antibodies targeting the proteins HA (clones 310-18A3, AV.G4, CR6261, 8H5, AV.D1, AV.C4, FLD127, FLD84, FLD93, FLD20, FLD21, A3, T1-3B, FB75, HA, FC41, FE17), NS1 (clone n.3, clone n.10, clone n.11), or the whole virus (clone H5.3).

Figures 1 and 2 depict our ELISA data for the clones against Influenza A HA [A/Hong Kong/483/97 (H5N1)]. This study confirms the antibodies binding to the antigen and compares the respective affinity.

The antibodies in our catalog are available in different engineered formats, including rabbit and mouse formats for detection applications, co-labeling studies and animal model research; human IgG1 and IgM used in neutralization assays and as serological controls; scFv format with His-tags, for applications where antibody fragments are desirable and for site-specific functionalization; and human IgG1 and mouse IgG2b Fc Silent™ formats, which reduce binding of Fc receptors.

Please contact us if you would like to find out more about our anti-influenza A H5N1 subtype antibodies, their applications and the different formats.

Article complied by Dr. Lucia Lupica-Spagnolo, Absolute Antibody Junior Product Developer

Catalog NumberClone NameAntigenCross ReactivityApplicationsFormats
Ab03636clone n.11NS1Influenza A virus
H5N1, H1N1, H3N2
Influenza B virus
ELISA, WB, inhibitionRabbit IgG
Human IgG1
Human IgG1 Fc Silent™
scFv fragment (His)
Ab03635clone n.10NS1Influenza A virus
H5N1, H1N1, H3N2
Influenza B virus
ELISA, WB, inhibitionRabbit IgG
Human IgG1
Human IgG1 Fc Silent™
scFv fragment (His)
Ab03634clone n.3NS1Influenza A virus
H5N1, H1N1, H3N2
Influenza B virus
ELISA, WB, inhibitionRabbit IgG
Human IgG1
Human IgG1 Fc Silent™
scFv fragment (His)
Ab02849310-18A3HAInfluenza A virus
H5N1, H1N1
ELISA, BLIRabbit IgG
Human IgG1
Human IgG1 Fc Silent™
Ab02205AV.G4HAInfluenza A virus H5N1

Does not cross-react with H5N3
ELISA, WBRabbit IgG
Human IgG1
scFv fragment (His)
Ab02199CR6261HAInfluenza A virus
H1N1, H5N1

Subtypes H1, H2, H5, H6, H8, and H9
NTRL, therapeuticRabbit IgG
Human IgG1
Human IgG1 Fc Silent™
Ab021008H5HAInfluenza A virus H5N1ELISA, Hemagglutination inhibition test, NTRLRabbit IgG
Human IgG1
Human IgG1 Fc Silent™
Mouse IgG2a
Mouse IgG2a – Fc silent
Ab02204AV.D1HAInfluenza A virus H5N1, H5N2, H5N3ELISA, NTRLRabbit IgG
Human IgG1
scFv fragment (His)
Ab02203AV.C4HAInfluenza A virus H5N1, H5N2, H5N3ELISA, WB, NTRLRabbit IgG
Human IgG1
scFv fragment (His)
Mouse IgG1
Ab00248FLD127HAInfluenza A virus H5N1ELISA, NTRL, RIARabbit IgG
Human IgG1
Ab00247FLD84HAInfluenza A virus H5N1ELISA, NTRL, RIARabbit IgG
Human IgG1
Ab00251FLD93HAInfluenza A virus H5N1NTRLRabbit IgG
Human IgG1
Ab00249FLD20HAInfluenza A virus H5N1NTRLRabbit IgG
Human IgG1
Ab00250FLD21HAInfluenza A virus H5N1NTRLRabbit IgG
Human IgG1
Ab03021A3HA cleavage siteInfluenza A virus H5N1

Does not cross-react with H1N1, H7N7
ELISA, IF, SPRRabbit IgG
Human IgG1
Human IgM
Mouse IgG1
Mouse Fab fragment
Ab00798H5.3H5Influenza A virus H5N1NTRLRabbit IgG
Human IgG1
Human IgG1 Fc Silent™
Ab01106T1-3BHAInfluenza A virus H5N1ELISA, IF, hemagglutination inhibition test, microneutralization assays, virus titrationRabbit IgG
Human IgG1
Human IgM
Mouse IgG2a
Mouse IgG2a Fc Silent™
Mouse IgM
Ab00148FB75IHAInfluenza A virus H1N1, H5N1, H6N1, H9N2

Does not cross-react with H2N2, H3N2 and H7N7
ELISA, NTRLHuman IgG1
Mouse IgG1
Ab00151HAHAInfluenza A virus H1N1, H5N1, H6N1, and H9N2

Does not cross-react with H1N1, H5N1, H6N1 and H9N2
ELISAHuman IgG1
Mouse IgG1
Ab00149FC41HAInfluenza A Virus
H1N1, H5N1, H6N1, and H9N2

Does not cross-react with H3N2 and H7N7
ELISAHuman IgG1
Ab00150FE17HAInfluenza A Virus
H1N1 and H5N1

Does not cross-react with H2N2, H3N3, H6N1, H7N3 and H9N2
ELISAHuman IgG1
Mouse IgG1