RESUMO
The surface of the mature dengue virus (DENV) particle is covered with 180 envelope (E) proteins arranged as homodimers that lie relatively flat on the virion surface. Each monomer consists of three domains (ED1, ED2, and ED3), of which ED3 contains the critical neutralization determinant(s). In this study, a large panel of DENV-2 recombinant ED3 mutant proteins was used to physically and biologically map the epitopes of five DENV complex-specific monoclonal antibodies (MAbs). All five MAbs recognized a single antigenic site that includes residues K310, I312, P332, L389, and W391. The DENV complex antigenic site was located on an upper lateral surface of ED3 that was distinct but overlapped with a previously described DENV-2 type-specific antigenic site on ED3. The DENV complex-specific MAbs required significantly higher occupancy levels of available ED3 binding sites on the virion, compared to DENV-2 type-specific MAbs, in order to neutralize virus infectivity. Additionally, there was a great deal of variability in the neutralization efficacy of the DENV complex-specific MAbs with representative strains of the four DENVs. Overall, the differences in physical binding and potency of neutralization observed between DENV complex- and type-specific MAbs in this study demonstrate the critical role of the DENV type-specific antibodies in the neutralization of virus infectivity.
Assuntos
Vírus da Dengue/imunologia , Mapeamento de Epitopos , Epitopos Imunodominantes/imunologia , Proteínas do Envelope Viral/imunologia , Alanina/metabolismo , Sequência de Aminoácidos , Substituição de Aminoácidos , Animais , Anticorpos Monoclonais/imunologia , Anticorpos Antivirais/imunologia , Afinidade de Anticorpos , Chlorocebus aethiops , Vírus da Dengue/isolamento & purificação , Ensaio de Imunoadsorção Enzimática , Glicina/metabolismo , Epitopos Imunodominantes/genética , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Testes de Neutralização , Estrutura Terciária de Proteína/genética , Células Vero , Proteínas do Envelope Viral/química , Proteínas do Envelope Viral/genéticaRESUMO
Yellow fever virus (YFV), a reemerging disease agent in Africa and South America, is the prototype member of the genus Flavivirus. Based on examination of the prM/M, E and 3' non-coding regions of the YFV genome, previous studies have identified seven genotypes of YFV, including the Angolan, east/central African and east African genotypes, which are highly divergent from the prototype strain Asibi. In this study, full genome analysis was used to expand upon these genetic relationships as well as on the very limited full genome database for YFV. This study was the first to investigate genomic sequences of YFV strains from east and central Africa (Angola71, Uganda48a and Ethiopia61b). All three viruses had genomes of 10 823 nt in length. Compared with the prototype strain Asibi (from west Africa) they were approximately 25 % divergent in nucleotide sequence and 7 % divergent in amino acid sequence. Comparison of multiple flaviviruses in the N-terminal region of NS4B showed that amino acid sequences were variable and that west African strains of YFV had an amino acid deletion at residue 21. Additionally, N-linked glycosylation sites were conserved between viral genotypes, while codon usage varied between strains.