RESUMO
To characterize neutralizing mimotopes, phages were selected from a 12-mer phage display library using three anti-porcine reproductive and respiratory syndrome virus (PRRSV) neutralizing monoclonal antibodies: (1) A1; (2) A2; and (3) A7. Of these, A2 and A7 recognize the mimotope, P2, which contains the SRHDHIH motif, which has conserved consensus sequences from amino acid positions 156 to 161 in the N-terminal ectodomain of GP3. The artificial multi-epitope gene, mp2, was designed by combining three repeats of the mimotope P2. The resulting sequence was inserted into the swinepox virus (SPV) genome to construct a recombinant swinepox virus (rSPV-mp2). The rSPV-mp2 was able to stably express the multi-epitope peptide, mP2, in vitro. The rSPV-mp2 immunized pigs exhibited a significantly shorter fever duration compared with the wtSPV treated group (P < 0.05). There was an enhanced humoral and cellular immune response, decreased number of PRRSV genomic copies, and a significant reduction in the gross lung pathology (P < 0.05) was observed following PRRSV infection in rSPV-mp2-immunized animals. The results suggest that the recombinant rSPV-mp2 provided pigs with significant protection against PRRSV infection.
Assuntos
Epitopos/genética , Peptídeos/genética , Vírus da Síndrome Respiratória e Reprodutiva Suína/metabolismo , Suipoxvirus/imunologia , Sequência de Aminoácidos , Animais , Anticorpos Neutralizantes/sangue , Anticorpos Antivirais/sangue , Temperatura Corporal , Epitopos/química , Epitopos/imunologia , Interferon gama/sangue , Interleucina-4/sangue , Pulmão/patologia , Biblioteca de Peptídeos , Peptídeos/química , Peptídeos/imunologia , Síndrome Respiratória e Reprodutiva Suína/metabolismo , Síndrome Respiratória e Reprodutiva Suína/prevenção & controle , Vírus da Síndrome Respiratória e Reprodutiva Suína/genética , Vírus da Síndrome Respiratória e Reprodutiva Suína/imunologia , RNA Viral/sangue , Suipoxvirus/genética , Suipoxvirus/metabolismo , Suínos , Vacinas Virais/genética , Vacinas Virais/imunologia , Vacinas Virais/metabolismoRESUMO
Vaccinia virus (VACV) K1L and C7L function equivalently in many mammalian cells to support VACV replication and antagonize antiviral activities induced by type I interferons (IFNs). While K1L is limited to orthopoxviruses, genes that are homologous to C7L are found in diverse mammalian poxviruses. In this study, we showed that the C7L homologues from sheeppox virus and swinepox virus could rescue the replication defect of a VACV mutant deleted of both K1L and C7L (vK1L(-)C7L(-)). Interestingly, the sheeppox virus C7L homologue could rescue the replication of vK1L(-)C7L(-) in human HeLa cells but not in murine 3T3 and LA-4 cells, in contrast to all other C7L homologues. Replacing amino acids 134 and 135 of the sheeppox virus C7L homologue, however, made it functional in the two murine cell lines, suggesting that these two residues are critical for antagonizing a putative host restriction factor which has some subtle sequence variation in human and murine cells. Furthermore, the C7L family of host range genes from diverse mammalian poxviruses were all capable of antagonizing type I IFN-induced antiviral activities against VACV. Screening of a library of more than 350 IFN-stimulated genes (ISGs) identified interferon-regulated factor 1 (IRF1) as an inhibitor of vK1L(-)C7L(-) but not wild-type VACV. Expression of either K1L or C7L, however, rendered vK1L(-)C7L(-) resistant to IRF1-induced antiviral activities. Altogether, our data show that K1L and C7L antagonize IRF1-induced antiviral activities and that the host modulation function of C7L is evolutionally conserved in all poxviruses that can readily replicate in tissue-cultured mammalian cells.
Assuntos
Especificidade de Hospedeiro/genética , Fator Regulador 1 de Interferon/metabolismo , Interferon Tipo I/metabolismo , Poxviridae/genética , Poxviridae/metabolismo , Proteínas Virais/genética , Sequência de Aminoácidos , Animais , Capripoxvirus/genética , Capripoxvirus/metabolismo , Linhagem Celular , Chlorocebus aethiops , Ordem dos Genes , Humanos , Fator Regulador 1 de Interferon/genética , Camundongos , Dados de Sequência Molecular , Alinhamento de Sequência , Suipoxvirus/genética , Suipoxvirus/metabolismo , Vírus Vaccinia/genética , Vírus Vaccinia/metabolismo , Proteínas Virais/metabolismo , Replicação Viral/genéticaRESUMO
The interferon-induced protein kinase PKR is activated upon binding double-stranded RNA and phosphorylates the translation initiation factor eIF2alpha on Ser-51 to inhibit protein synthesis in virally infected cells. Swinepox virus C8L and vaccinia virus K3L gene products structurally resemble the amino-terminal third of eIF2alpha. We demonstrate that the C8L protein, like the K3L protein, can reverse the toxic effects caused by high level expression of human PKR in yeast cells. In addition, expression of either the K3L or C8L gene product was found to reverse the inhibition of reporter gene translation caused by PKR expression in mammalian cells. The inhibitory function of the K3L and C8L gene products in these assays was found to be critically dependent on residues near the carboxyl-termini of the proteins including a sequence motif shared among eIF2alpha and the C8L and K3L gene products. Thus, despite significant sequence differences both the C8L and K3L proteins function as pseudosubstrate inhibitors of PKR.
