RESUMEN
Type I interferon (IFN) induction is an immediate response to virus infection, and very high levels of these cytokines are produced when the Toll-like receptors (TLRs) expressed at high levels by plasmacytoid dendritic cells (pDCs) are triggered by viral nucleic acids. Unlike many RNA viruses, respiratory syncytial virus (RSV) does not appear to activate pDCs through their TLRs and it is not clear how this difference affects IFN-alpha/beta induction in vivo. In this study, we investigated type I IFN production triggered by RSV or influenza A virus infection of BALB/c mice and found that while both viruses induced IFN-alpha/beta production by pDCs in vitro, only influenza virus infection could stimulate type I IFN synthesis by pDCs in vivo. In situ hybridization studies demonstrated that the infected respiratory epithelium was a major source of IFN-alpha/beta in response to either infection, but in pDC-depleted animals only type I IFN induction by influenza virus was impaired.
Asunto(s)
Subtipo H1N1 del Virus de la Influenza A/inmunología , Interferón-alfa/inmunología , Interferón beta/inmunología , Infecciones por Orthomyxoviridae/inmunología , Infecciones por Virus Sincitial Respiratorio/inmunología , Virus Sincitiales Respiratorios/inmunología , Animales , Bovinos , Línea Celular , Células Dendríticas/inmunología , Células Dendríticas/patología , Células Dendríticas/virología , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Infecciones por Orthomyxoviridae/patología , Mucosa Respiratoria/inmunología , Mucosa Respiratoria/patología , Mucosa Respiratoria/virología , Infecciones por Virus Sincitial Respiratorio/patologíaRESUMEN
Two novel spliced genes (UL131A and UL128) flanking UL130 were predicted from sequence comparisons between human cytomegalovirus (HCMV) and its closest known relative, chimpanzee cytomegalovirus (CCMV), and the splicing patterns were confirmed by mRNA mapping experiments. Both genes were transcribed with late kinetics and shared a polyadenylation site. Comparisons with wild-type HCMV in infected human tissues showed that three of five isolates passaged in cell culture contained disruptions of UL128, one was frameshifted in UL131A and one exhibited a deletion affecting UL131A and UL130. CCMV and the Colburn strain of simian cytomegalovirus, which have been passaged in cell culture, also exhibit disruptions of UL128. These observations indicate that expression of either one of UL128 and UL131A is deleterious to growth of primate cytomegaloviruses in cell culture. Although the functions of these genes are unknown, sequence comparisons suggest that UL128 encodes a beta-chemokine.
Asunto(s)
Citomegalovirus/genética , Empalme del ARN , Proteínas Virales/genética , Proteínas Virales/metabolismo , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Línea Celular , Citomegalovirus/metabolismo , Humanos , Datos de Secuencia Molecular , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN Viral/genética , ARN Viral/metabolismo , Mapeo Restrictivo , Análisis de Secuencia de ADNRESUMEN
A significant proportion of the human cytomegalovirus (HCMV) genome comprises 12 multigene families that probably arose by gene duplication. One, the RL11 family, contains 12 members, most of which are predicted to encode membrane glycoproteins. Comparisons of sequences near the left end of the genome in several HCMV strains revealed two adjacent open reading frames that potentially encode related proteins: RL6, which is hypervariable, and RL5A, which has not been recognized previously. These genes potentially encode a domain that is the hallmark of proteins encoded by the RL11 family, and thus constitute two new members. A homologous domain is also present in a subset of human adenovirus E3 membrane glycoproteins. Evolution of genes specifying the shared domain in cytomegaloviruses and adenoviruses is characterized by extensive divergence, gene duplication and selective sequence loss. These features prompt speculation about the roles of these genes in the two virus families.
Asunto(s)
Proteínas E3 de Adenovirus/genética , Adenovirus Humanos/genética , Citomegalovirus/genética , Genes Virales , Adenovirus Humanos/química , Secuencia de Aminoácidos , Secuencia de Bases , Citomegalovirus/química , ADN Viral , Humanos , Datos de Secuencia Molecular , Sistemas de Lectura Abierta , Alineación de Secuencia , Análisis de Secuencia de ADN , Homología de Secuencia de Ácido NucleicoRESUMEN
The gene complement of wild-type human cytomegalovirus (HCMV) is incompletely understood, on account of the size and complexity of the viral genome and because laboratory strains have undergone deletions and rearrangements during adaptation to growth in culture. We have determined the sequence (241 087 bp) of chimpanzee cytomegalovirus (CCMV) and have compared it with published HCMV sequences from the laboratory strains AD169 and Toledo, with the aim of clarifying the gene content of wild-type HCMV. The HCMV and CCMV genomes are moderately diverged and essentially collinear. On the basis of conservation of potential protein-coding regions and other sequence features, we have discounted 51 previously proposed HCMV ORFs, modified the interpretations for 24 (including assignments of multiple exons) and proposed ten novel genes. Several errors were detected in the published HCMV sequences. We presently recognize 165 genes in CCMV and 145 in AD169; this compares with an estimate of 189 unique genes for AD169 made in 1990. Our best estimate for the complement of wild-type HCMV is 164 to 167 genes.
