Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 2 de 2
Filtrar
Más filtros











Base de datos
Intervalo de año de publicación
1.
J Virol ; 94(9)2020 04 16.
Artículo en Inglés | MEDLINE | ID: mdl-32075927

RESUMEN

The capsid protein (Cap) is the sole structural protein and the main antigen of porcine circovirus type 2 (PCV2). Structural loops of the Cap play crucial roles in viral genome packaging, capsid assembly, and virus-host interactions. Although the molecular mechanisms are yet unknown, the carboxyl terminus (CT) of the PCV2 Cap is known to play critical roles in the evolution, pathogenesis, and proliferation of this virus. In this study, we investigated functions of CT. Removal of this loop leads to abrogation of the in vitro Cap self-assembly into virus-like particles (VLPs). Likewise, the mutated virus resists rescue from PK15 cell culture. A conserved PXXP motif in the CT is dispensable for VLP assembly and subsequent cell entry. However, its removal leads to the subsequent failure of virus rescued from PK15 cells. Furthermore, substituting either the PCV1 counterpart or an AXXA for the PXXP motif still supports virus rescue from cell culture but results in a dramatic decrease in viral titers compared with wild type. In particular, a strictly conserved residue (227K) in the CT is essential for VLP entry into PK15 cells, and its mutation to alanine greatly attenuates cell entry of the VLPs, supporting a mechanism for the failure to rescue a mutated PCV2 infectious DNA clone (K227A) from PK15 cell culture. These results suggest the CT of the PCV2 Cap plays critical roles in virus assembly, viral-host cell interaction(s), and virus propagation in vitroIMPORTANCE The carboxyl terminus (CT) of porcine circovirus type 2 (PCV2) capsid protein (Cap) was previously reported to be associated with immunorecognition, alterations of viral titer in swine sera, and pathogenicity. However, the molecular mechanisms underlying these effects remain unknown. In this study, roles of the critical residues and motifs of the CT are investigated with respect to virus-like particle (VLP) assembly, cell entry, and viral proliferation. The results revealed that the positively charged 227K of the CT is essential for both cell entry of PCV2 VLPs and virus proliferation. Our findings, therefore, suggest that the CT should be considered one of the key epitopes, recognized by neutralizing antibodies, for vaccine design and a target for drug development to prevent PCV2-associated diseases (PCVADs). Furthermore, it is important to respect the function of 227K for its role in cell entry if using either PCV2 VLPs for nanoscale DNA/drug cell delivery or using PCV2 VLPs to display a variety of foreign epitopes for immunization.


Asunto(s)
Proteínas de la Cápside/metabolismo , Circovirus/metabolismo , Animales , Anticuerpos Neutralizantes/sangre , Anticuerpos Antivirales/inmunología , Cápside/metabolismo , Proteínas de la Cápside/genética , Circoviridae/genética , Circoviridae/metabolismo , Infecciones por Circoviridae/genética , Infecciones por Circoviridae/metabolismo , Circovirus/genética , Epítopos/inmunología , Porcinos , Enfermedades de los Porcinos/virología , Vacunas de Partículas Similares a Virus/inmunología , Ensamble de Virus/genética , Internalización del Virus
2.
J Gen Virol ; 78 ( Pt 7): 1795-9, 1997 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-9225058

RESUMEN

The major open reading frame of banana bunchy top virus (BBTV) DNA-1 encodes a putative replication initiation protein (Rep). In vitro, a fusion protein of BBTV Rep linked to a maltose-binding protein exhibited both site-specific nicking and joining activities. These activities were dependent on the presence of Mg2+ or Mn2+, but did not require ATP. The fusion protein specifically cleaved ssDNA between bases +7 and +8 of a conserved nonanucleotide loop sequence which is present in the virion-strand of the stem-loop common region of each BBTV component. During this reaction, the fusion protein became covalently attached to the 5' end of the 3'cleavage product. After the nicking reactions, the fusion protein was also capable of catalysing the joining of two nicked ssDNA fragments in a site-specific manner. Based on these activities, BBTV Rep would appear to be very similar to the Rep proteins of the geminiviruses.


Asunto(s)
Circoviridae/metabolismo , ADN Helicasas/metabolismo , Proteínas de Unión al ADN , Transactivadores/metabolismo , Proteínas Virales/metabolismo , Cationes Bivalentes , Circoviridae/enzimología , Circoviridae/genética , ADN Helicasas/genética , ADN de Cadena Simple/metabolismo , ADN Viral/metabolismo , Frutas/virología , Conformación de Ácido Nucleico , Oligodesoxirribonucleótidos/metabolismo , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Transactivadores/genética , Proteínas Virales/genética
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA