Enteroviruses proteolyze nuclear pore complex (NPC) proteins (Nups) during infection, leading to disruption of host nuclear transport pathways and alterations in nuclear permeability. To better understand how enteroviruses exert these effects on nuclear transport, the mechanisms and consequences of Nup98 proteolysis were examined. The results indicate that Nup98 is rapidly targeted for degradation following enterovirus infection and that this is mediated by the enterovirus 2A protease (2A pro ). Incubation of bacterially expressed or in vitro-translated Nup98 with 2A pro results in proteolytic cleavage at multiple sites in vitro, indicating that 2A pro cleaves Nup98 directly. Site-directed mutagenesis of putative cleavage sites identified Gly374 and Gly552 as the sites of 2A pro proteolysis in Nup98 in vitro and in infected cells. Indirect immunofluorescence assays using an antibody that recognizes the N terminus of Nup98 revealed that proteolysis releases the N-terminal FG-rich region from the NPC. In contrast, similar analyses using an antibody to the C terminus indicated that this region is retained at the nuclear rim. Nup88, a core NPC component that serves as a docking site for Nup98, also remains at the NPC in infected cells. These findings support a model whereby the selective removal of Nup FG repeat domains leads to increased NPC permeability and inhibition of certain transport pathways, while retention of structural domains maintains the overall NPC structure and leaves other transport pathways unaffected. IMPORTANCEEnteroviruses are dependent upon host nuclear RNA binding proteins for efficient replication. This study examines the mechanisms responsible for alterations in nuclear transport in enterovirus-infected cells that lead to the cytoplasmic accumulation of these proteins. The results demonstrate that the enterovirus 2A protease directly cleaves the nuclear pore complex (NPC) protein, Nup98, at amino acid positions G374 and G552 both in vitro and in infected cells. Cleavage at these positions results in the selective removal of the FG-containing N terminus of Nup98 from the NPC, while the C terminus remains associated. Nup88, a core component of the NPC that serves as a docking site for the C terminus of Nup98, remains associated with the NPC in infected cells. These findings help to explain the alterations in permeability and nuclear transport in enterovirus-infected cells and how NPCs remain functional for certain trafficking pathways despite significant alterations to their compositions. Members of the Picornaviridae are small nonenveloped viruses with positive-strand RNA genomes that are responsible for a variety of diseases in humans and animals (reviewed in reference 1). The family includes enteroviruses, such as poliovirus and rhinovirus, along with cardioviruses, such as encephalomyocarditis virus and Theiler's murine encephalomyelitis virus. Following entry of these viruses into the host cell, translation and replication of the RNA genome occur exclusively in the cytoplasm. Desp...

IntroductionThe implementation of a home smoking ban (HSB) is associated with tobacco use cessation. We identified which quitline callers were most likely to report 30-day cessation among those who implemented complete HSBs after enrollment.MethodsOur sample consisted of callers to the Arizona Smokers’ Helpline who enrolled from January 1, 2011, through July 26, 2015, and who reported no HSB at enrollment and a complete HSB by 7-month follow-up. We used logistic regression to estimate associations between no use of tobacco in the previous 30 days (30-day quit) at 7-month follow-up and demographic characteristics, health conditions, tobacco use, and cessation strategies.ResultsAt 7-month follow-up, 65.4% of 399 callers who implemented a complete HSB reported 30-day quit. Lower odds of tobacco use cessation were associated with having a chronic health condition (odds ratio [OR], 0.31; 95% confidence interval [CI], 0.18–0.56) and living with other smokers (OR, 0.46; 95% CI, 0.29–0.73). Higher odds of tobacco cessation were associated with completing 5 or more telephone coaching sessions (OR, 2.48; 95% CI, 1.54–3.98) and having confidence to quit (OR, 2.05; 95% CI, 1.05–3.99). However, confidence to quit was not significant in the sensitivity analysis.ConclusionImplementing an HSB after enrolling in quitline services increases the likelihood of cessation among some tobacco users. Individuals with complete HSBs were more likely to quit if they did not have a chronic health condition, did not live with another smoker, and were actively engaged in coaching services. These findings may be used by quitlines to develop HSB intervention protocols primarily targeting tobacco users most likely to benefit from them.

In an earlier study, protein-based barriers to horizontal gene transfer were investigated by placing the bacteriophage G4 G gene, encoding the major spike protein, into the φX174 genome. The foreign G protein promoted off-pathway assembly reactions, resulting in a lethal phenotype. After three targeted genetic selections, one of two foreign spike proteins was productively integrated into the φX174 system: the complete G4 or a recombinant G4/φX174 protein (94% G4:6% φX174). However, strain fitness was very low. In this study, the chimeras were characterized and experimentally evolved. Inefficient assembly was the primary contributor to low fitness: accordingly, mutations affecting assembly restored fitness. The spike protein preference of the ancestral and evolved strains was determined in competition experiments between the foreign and φX174G proteins. Before adaptation, both G proteins were incorporated into virions; afterwards, the foreign proteins were strongly preferred. Thus, a previously inhibitory protein became the preferred substrate during assembly.