RESUMO
Amino acid positions recognized by monoclonal antibodies (MAbs) in the influenza A virus nucleoprotein (NP) have been reported. As these residues were scattered in the three-dimensional (3D) structure of NP, no patterns of the architecture of antibody-binding sites could be inferred. Here, we used site-specific mutagenesis and ELISA to screen the amino acids surrounding position 470 recognized by the MAb 3/1 as a linear epitope. Ten amino acid residues involved in the reaction of NP with the MAb 3/1 and the MAb 469/6 were identified. Our data are the first to outline a compact site recognized by MAbs in the 3D structure of the influenza virus NP.
Assuntos
Sítios de Ligação de Anticorpos/genética , Vírus da Influenza A/genética , Vírus da Influenza A/imunologia , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/imunologia , Proteínas do Core Viral/genética , Proteínas do Core Viral/imunologia , Análise Mutacional de DNA , Vírus da Influenza A/química , Modelos Moleculares , Mutagênese Sítio-Dirigida , Proteínas do Nucleocapsídeo , Conformação Proteica , Proteínas de Ligação a RNA/química , Proteínas do Core Viral/químicaRESUMO
Abstract Influenza virus nucleoprotein (NP) binds to the viral genome RNA and forms the internal ribonucleoprotein complex of the virus particle. Avian and human influenza virus NP have characteristic differences at several amino acid positions. It is not known whether any of these differences can be recognized by antibodies. In the present study five monoclonal antibodies (MAbs) were produced against NP of A/Duck/Novosibirsk/56/05 (H5N1) influenza virus. Two MAbs discerned human and avian influenza strains on ELISA testing. The NP expressed in a prokaryotic system was used for the analysis of site-specific mutants carrying amino acid substitutions in the relevant positions. Amino acid residues in positions 100 and 101 were shown to be recognized by the MAbs. The residue in position 100 is host-specific, and its recognition by the MAb 2E6 may be useful for the differentiation of human and avian viruses. The data are discussed in view of the effects of amino acid substitutions in influenza virus NP affecting both host range and antibody-binding specificity.