RESUMO
Small colony variants (SCV) of Staphylococcus aureus have been reported as implicated in chronic infections. Here, we investigated the genomic and transcriptomic changes involved in the evolution from a wild-type to a SCV from in a patient with prosthetic joint infection relapse. The SCV presented a stable phenotype with no classical auxotrophy and the emergence of rifampicin resistance. Whole Genome Sequencing (WGS) analysis showed only the loss of a 42.5 kb phage and 3 deletions, among which one targeting the rpoB gene, known to be the target of rifampicin and to be associated to SCV formation in the context of a constitutively active stringent response. Transcriptomic analysis highlighted a specific signature in the SCV strain including a complex, multi-level strategy of survival and adaptation to chronicity within the host including a protection from the inflammatory response, an evasion of the immune response, a constitutively activated stringent response and a scavenging of iron sources.
Assuntos
Artrite Infecciosa/microbiologia , Fenótipo , Infecções Relacionadas à Prótese/microbiologia , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus , Antibacterianos/farmacologia , Doença Crônica , Perfilação da Expressão Gênica , Genoma Bacteriano , Genômica/métodos , Humanos , Testes de Sensibilidade Microbiana , Recidiva , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/fisiologia , TranscriptomaRESUMO
During the post-transcriptional events of the HIV-2 replication cycle, the full-length unspliced genomic RNA (gRNA) is first used as an mRNA to synthesize Gag and Gag-Pol proteins and then packaged into progeny virions. However, the mechanisms responsible for the coordinate usage of the gRNA during these two mutually exclusive events are poorly understood. Here, we present evidence showing that HIV-2 expression induces stress granule assembly in cultured cells. This contrasts with HIV-1, which interferes with stress granules assembly even upon induced cellular stress. Moreover, we observed that the RNA-binding protein and stress granules assembly factor TIAR associates with the gRNA to form a TIAR-HIV-2 ribonucleoprotein (TH2RNP) complex localizing diffuse in the cytoplasm or aggregated in stress granules. Although the assembly of TH2RNP in stress granules did not require the binding of the Gag protein to the gRNA, we observed that increased levels of Gag promoted both translational arrest and stress granule assembly. Moreover, HIV-2 Gag also localizes to stress granules in the absence of a 'packageable' gRNA. Our results indicate that the HIV-2 gRNA is compartmentalized in stress granules in the absence of active translation prior to being selected for packaging by the Gag polyprotein.
Assuntos
Grânulos Citoplasmáticos/virologia , HIV-2/genética , RNA Viral/metabolismo , Montagem de Vírus , Grânulos Citoplasmáticos/metabolismo , Fator de Iniciação 2 em Eucariotos/metabolismo , Genoma Viral , HIV-2/fisiologia , Células HeLa , Humanos , Biossíntese de Proteínas , RNA Viral/análise , RNA Viral/biossíntese , Proteínas de Ligação a RNA/química , Proteínas de Ligação a RNA/metabolismo , Ribonucleoproteínas/metabolismo , Estresse Fisiológico , Replicação Viral , Produtos do Gene gag do Vírus da Imunodeficiência Humana/biossíntese , Produtos do Gene gag do Vírus da Imunodeficiência Humana/genéticaRESUMO
The small mRNA (SmRNA) of all Bunyaviridae encodes the nucleocapsid (N) protein. In 4 out of 5 genera in the Bunyaviridae, the smRNA encodes an additional nonstructural protein denominated NSs. In this study, we show that Andes hantavirus (ANDV) SmRNA encodes an NSs protein. Data show that the NSs protein is expressed in the context of an ANDV infection. Additionally, our results suggest that translation initiation from the NSs initiation codon is mediated by ribosomal subunits that have bypassed the upstream N protein initiation codon through a leaky scanning mechanism.
Assuntos
Infecções por Hantavirus/virologia , Orthohantavírus/genética , Iniciação Traducional da Cadeia Peptídica , RNA Viral/genética , Proteínas não Estruturais Virais/genética , Linhagem Celular , Regulação Viral da Expressão Gênica , Orthohantavírus/metabolismo , Humanos , Fases de Leitura Aberta , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Viral/metabolismo , Proteínas não Estruturais Virais/metabolismoRESUMO
In the process of translation of eukaryotic mRNAs, the 5' cap and the 3' poly(A) tail interact synergistically to stimulate protein synthesis. Unlike its cellular counterparts, the small mRNA (SmRNA) of Andes hantavirus (ANDV), a member of the Bunyaviridae, lacks a 3' poly(A) tail. Here we report that the 3' untranslated region (3'UTR) of the ANDV SmRNA functionally replaces a poly(A) tail and synergistically stimulates cap-dependent translation initiation from the viral mRNA. Stimulation of translation by the 3'UTR of the ANDV SmRNA was found to be independent of viral proteins and of host poly(A)-binding protein.