Project description:Influenza A virus encodes promoters in both the sense and antisense orientations. These support the generation of new genomes, antigenomes, and mRNA transcripts. Characterization of the influenza promoters using minimal replication assays—transfections with viral polymerase, nucleoprotein, and a genomic template—defined their sequence as 13nt at the 5’ end of the viral genomic RNA (U13) and 12nt at the 3’ end (U12).Other than a single position the U12 and U13 sequences are identical between all eight RNA molecules that comprise the segmented influenza genome.Nevertheless, each segment can exhibit different transcriptional dynamics despite possessing identical promoters.Minimal replication assays lack the influenza protein NS2, which can modulate transcription and replication differentially between influenza segments.This suggests that NS2 expression may redefine the influenza A virus promoter.In this work we assess how internal regions of sequence in two genomic segments, HA and PB1, may contribute to NS2-dependent replication as well as map such interactions down to individual nucleotides in PB1. We find that the expression of NS2 significantly alters sequence requirements for efficient replication beyond the identical U12 and U13 sequence, providing a mechanism for the divergent replication and transcription dynamics across the influenza A virus genome.
Project description:Encoding only ten major proteins, Influenza A virus (IAV) gains access to both the cell and nucleus, replicates its eight genomic segments, then enters the cytoplasm to assemble and egress. This is achieved through an expansive network of interactions with the host and a coordinated production of viral components. Here we show that upon infection, primary transcription of the virus results in the accumulation of the splice product, Nuclear Export Protein (NEP), which associates with the viral polymerase leading to the synthesis of segment-specific small viral RNAs (svRNAs). Here we demonstrate that svRNA biology is responsible for coordinating segment-specific amplification and is predominantly required for amplification of the three larger polymerase segments. Generation of svRNA ambiguity results in predictable changes in segment-specific vRNA levels and up to a five log attenuation. Together, these data elucidate the molecular function of svRNAs as essential mediators responsible for maintaining a stoichiometric balance between genomic segments and establish these small RNAs as functional components of the virus.
Project description:Influenza A virus (IAV) is a threat to mankind because it generates yearly epidemics and poorly predictable sporadic pandemics with catastrophic potential. Influenza has a small RNA genome (~14 Kb) composed of 8 mini-chromosomes (segments). Segments encode both structural proteins and proteins expressed only during infection. Segments are constituted by a 5’UTR followed by a coding region and a 3’UTR. Transcription of IAV RNA into mRNA depends on host RNA Polymerase II, as the viral polymerase cleaves 5’ capped cellular nascent transcripts to be used as primers to initiate mRNA synthesis. We hypothesized that host nascent transcripts bearing AUG could generate upstream ORFs in the viral segments, a phenomenon that would depend on the translatability of the viral 5’UTRs. Using orthogonal datasets we report the existence of this mechanism, which generate host-virus chimeric proteins. We show that most segments encode proteins in this manner, expanding the proteome diversity of IAV in infected cells. Host-virus chimeric proteins are conserved across IAV strains, pointing to an evolutionary conservation of function achieved by sampling of the evolutionary space before gene fixation. Thus, we discover a mechanism that generate human-virus chimeric proteins during infection.
Project description:The purpose is to obtain samples for transcriptional analysis in triplicate wells using wild type West Nile virus (WNV NY99 clone 382; WNVWT) and mutant virus (WNVE218A) in mouse granule cell neurons. This data set comprises two complete biological replicate experiments conducted in the same conditions and with data processed independently.
Project description:Grapevine line pattern virus (GLPV) was described 30 years ago from Hungary, and in the lack of its sequence until now no additional information about its presence was reported. However High-Throughput Sequencing (HTS) applied on dsRNAs extracts recovered from a grapevine plant (accession Baco22A) infected with GLPV Grapevine line pattern virus (GLPV) allowed us to sequence it with different High-Throughput Sequencing (HTS) methods andthe assembleing of the full genome sequence of this virus. The availability of the sequence allowed us to validate the presence of the virus bot with RT-PCR and with Northern blot hybridization. These methods were also used to test its graft and seed transmission. In accordance as it was originally suggested its genome was found to comprise three RNA segments.Its RNA1 (3.160 bp), RNA2 (2.493 bp) and RNA3 (2.529 bp), encode four proteins, denoted 1a (Methyltransferase, helicase), 2a (RNA-dependent RNA Polymerase), 3a (Movement protein, MP) and 3b (Coat protein, CP). GLPV showed the highest amino acid identity (92%–99%) with all domains of Hop yellow virus (HYV), which is a tentative member of the genus Anulavirus of the family Bromoviridae. The phylogenetic trees constructed based on the amino acid sequences of 2a and 3b also confirmed the belongingness of GLPV to the genus Anulavirus, allocating it in one cluster together with the anulaviruses, and close to HYV. The very high sequence identity found between GLPV and HYV leaves no doubt that both are two isolates of the same viral species.
Project description:The purpose is to obtain samples for transcriptional analysis in triplicate wells using wild type West Nile virus (WNV NY99 clone 382; WNVWT) and mutant virus (WNVE218A) in mouse cortical neurons. This data set comprises two complete biological replicate experiments conducted in the same conditions and with data processed independently.