RESUMO
Most neutralizing antibodies elicited during influenza virus infection or by vaccination have a narrow spectrum because they usually target variable epitopes in the globular head region of hemagglutinin (HA). In this study, we describe a human monoclonal antibody (HuMAb), 5D7, that was prepared from the peripheral blood lymphocytes of a vaccinated volunteer using the fusion method. The HuMAb heterosubtypically neutralizes group 1 influenza A viruses, including seasonal H1N1, 2009 pandemic H1N1 (H1N1pdm) and avian H9N2, with a strong hemagglutinin inhibition activity. Selection of an escape mutant showed that the HuMAb targets a novel conformational epitope that is located in the HA head region but is distinct from the receptor binding site. Furthermore, Phe114Ile substitution in the epitope made the HA unrecognizable by the HuMAb. Amino acid residues in the predicted epitope region are also highly conserved in the HAs of H1N1 and H9N2. The HuMAb reported here may be a potential candidate for the development of therapeutic/prophylactic antibodies against H1 and H9 influenza viruses.
Assuntos
Anticorpos Monoclonais/biossíntese , Anticorpos Neutralizantes/biossíntese , Anticorpos Antivirais/biossíntese , Proteção Cruzada , Vírus da Influenza A Subtipo H1N1/imunologia , Vírus da Influenza A Subtipo H9N2/imunologia , Influenza Humana/prevenção & controle , Sequência de Aminoácidos , Animais , Antígenos Virais/química , Antígenos Virais/imunologia , Mapeamento de Epitopos , Epitopos/química , Epitopos/imunologia , Testes de Inibição da Hemaglutinação , Glicoproteínas de Hemaglutininação de Vírus da Influenza/química , Glicoproteínas de Hemaglutininação de Vírus da Influenza/imunologia , Humanos , Hibridomas/imunologia , Vacinas contra Influenza/administração & dosagem , Influenza Humana/imunologia , Influenza Humana/virologia , Masculino , Camundongos , Modelos Moleculares , Dados de Sequência Molecular , Conformação Proteica , Vacinação , Adulto JovemRESUMO
We report 25 env gp160 sequences from patients in three geographically distinct districts of Thailand, i.e., Lampang in the north, Trang in the south and Rayong in the east. One of these is a CRF01_AE/subtype B recombinant and the other 24 sequences are purely CRF01_AE. Very little interpopulation diversity was observed between the sequences from the three different geographic regions and from those previously reported by our laboratory from central Thailand. Potential N-linked glycosylation sites (PNLGs) were reasonably conserved among the 25 sequences: we found 15 highly conserved PNLGs on gp120 and 4 almost fully conserved PNLGs on gp41. Analysis of coreceptor tropism revealed that six of the isolates were dual tropic and the others were R5 tropic. We also examined a rare seven amino acid deletion found in one isolate at position 847-853 on gp41. These results may enhance our understanding of HIV-1 currently circulating in Thailand.
