RESUMEN
Establishing a nonproductive, quiescent infection within monocytes is essential for the spread of human cytomegalovirus (HCMV). We investigated the mechanisms through which HCMV establishes a quiescent infection in monocytes. US28 is a virally encoded G protein-coupled receptor (GPCR) that is essential for silent infections within cells of the myeloid lineage. We found that preformed US28 was rapidly delivered to monocytes by HCMV viral particles, whereas the de novo synthesis of US28 was delayed for several days. A recombinant mutant virus lacking US28 (US28Δ) was unable to establish a quiescent infection, resulting in a fully productive lytic infection able to produce progeny virus. Infection with US28Δ HCMV resulted in the phosphorylation of the serine and threonine kinase Akt at Ser473 and Thr308, in contrast with the phosphorylation of Akt only at Ser473 after WT viral infection. Inhibiting the dual phosphorylation of Akt prevented the lytic replication of US28Δ, and ectopic expression of a constitutively phosphorylated Akt variant triggered lytic replication of wild-type HCMV. Mechanistically, we found that US28 was necessary and sufficient to attenuate epidermal growth factor receptor (EGFR) signaling induced during the entry of WT virus, which led to the site-specific phosphorylation of Akt at Ser473. Thus, particle-delivered US28 fine-tunes Akt activity by limiting HCMV-induced EGFR activation during viral entry, enabling quiescent infection in monocytes.
Asunto(s)
Citomegalovirus , Receptores ErbB , Monocitos , Proteínas Proto-Oncogénicas c-akt , Proteínas Virales , Replicación Viral , Citomegalovirus/fisiología , Citomegalovirus/genética , Citomegalovirus/metabolismo , Humanos , Monocitos/virología , Monocitos/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Proteínas Proto-Oncogénicas c-akt/genética , Fosforilación , Proteínas Virales/metabolismo , Proteínas Virales/genética , Receptores ErbB/metabolismo , Receptores ErbB/genética , Virión/metabolismo , Virión/genética , Receptores de Quimiocina/metabolismo , Receptores de Quimiocina/genética , Infecciones por Citomegalovirus/metabolismo , Infecciones por Citomegalovirus/virología , Infecciones por Citomegalovirus/genética , Transducción de SeñalRESUMEN
Establishing a non-productive quiescent/silent infection within monocytes is essential for spread of human cytomegalovirus (HCMV). Yet, how HCMV establishes a quiescent infection in monocytes remains unclear. US28 is a viral G protein-coupled receptor (GPCR) essential for silent infections within cells of the myeloid lineage. We found virion-associated US28 was rapidly delivered to monocytes, while de novo synthesized US28 was delayed for several days. A recombinant mutant virus lacking US28 (US28Δ) was unable to establish a quiescent infection, resulting in a fully productive lytic replication cycle. Mechanistically, viral entry of US28Δ phosphorylated Akt at both serine 473 (S473) and threonine 308 (T308), which contrasted with the site-specific phosphorylation of Akt at S473 following WT infection. Preventing Akt bi-phosphorylation prevented lytic replication of US28Δ, and ectopic expression of a constitutively phosphorylated Akt variant triggered lytic replication of WT infection. Our data demonstrate that virion-delivered US28 fine-tunes Akt activity to permit HCMV infection to enter a quiescent state following primary infection of monocytes.
RESUMEN
Vibrio fluvialis is an opportunistic waterborne and seafood-borne enteric pathogen capable of causing severe diarrhea leading to death. This pathogen is endemic to Bangladesh, a country which is a major producer of cultured shrimp and wild-caught prawns. In this study, we carried out whole-genome sequencing of three V. fluvialis organisms isolated from shrimp farm and river sediment showing strong pathogenic characteristics in vivo and in vitro and compared their genomes against other V. fluvialis and related pathogenic species to glean insights into their potential as pathogens. Numerous virulence-associated genes including hemolysins, cytolysins, three separate Type IV pili, Types II and VI secretion systems, biofilm, and the V. cholerae pathogenesis regulating gene, toxR, were identified. Moreover, we found strain S-10 to have the propensity to acquire antibiotic resistance genes through horizontal gene transfer. These findings indicate that shrimp farms and rivers could be potential sources of V. fluvialis organisms which are an infection threat of public health concern.