Project description:Pan-viral DNA array (PVDA) and high-throughput sequencing (HTS) are useful tools to identify novel virus of emerging diseases. However, both techniques have difficulties to identify viruses in clinical samples because of host genomic DNA (hgDNA) contamination. Both propidium monoazide (PMA) and ethidium bromide monoazide (EMA) have the capacity to bind free DNA but are cell membrane-impermeable and thus are unable to bind protected DNA and RNA such as viral genomic material. DNA modified by EMA or PMA is not amplifiable by polymerase. In order to assess the capacity of EMA or PMA to lower hgDNA, serum or lung tissue homogenates were spiked with porcine reproductive and respiratory virus (PRRSV) and were processed with different combination of treatment: with or without ultracentrifugation and incubation with or without different concentration of EMA or PMA. PVDA and HTS were used to evaluate the capacity of both techniques to detect the presence of PRRSV from each sample. Negative results were obtained by PVDA and low amount of PRRSV specific reads were obtained by HTS with untreated samples or samples treated only by ultracentrifugation. An increase capacity of PRRSV detection was observable by PVDA in EMA and PMA treated samples but PVDA best results were obtained following PMA treatment, with or without ultracentrifugation. HTS sensitivity was also improved by a treatment with EMA or PMA, but the number of reads was significantly higher in PMA treated samples. These results support the use of PMA as a treatment to increase sensitivity of PVDA and HTS. A non specific DNA probe is used as a negative hybridization control. Also, specifics probes targeting pUC19 plasmid DNA is used as a DNA array positive control as well as a localization control. Finally, there are 34 probes of 70 nucleotides spotted in duplicate were selected to target PRRSV conserved regions. A total of 80 different tests were done by DNA array in order to evaluate different treatments conditions with EMA or PMA, with or without ultracentrifugation. A total of 58 samples were tested on specific lung tissue homogenates spiked with different concentration of PRRSV and 12 samples were serum samples spiked with one concentration of PRRSV. Finally. A total of six samples

Project description:Cell lines derived from Chlorocebus sabaeus kidney were infected with an isolate of PRRSV-1 or PRRSV-2 and ribosome profiling was performed (this entry) in parallel with RNASeq (see related accession number). These datasets were used to analyse the viral and host translatome, frameshifting on the viral genome, and putative frameshift-related ribosome pausing events. For the PRRSV-1 experiments, MA-104 cells were infected with an isolate based on the Porcilis vaccine strain (KJ127878.1 but with several accumulated mutations, see associated publication) and harvested at 8 hpi after pre-treatment with cycloheximide (CHX). For the PRRSV-2 experiments, MARC-145 cells were infected with SD95-21 PRRSV (KC469618.1), and a mutant thereof (KO2). One group of samples was harvested at 9 hpi after pre-treatment with CHX, and another group of samples was harvested at 3, 6, 9 and 12 hpi by flash-freezing without CHX pre-treatment. For all samples, RNase I treatment was carried out, following which ribosomes and enclosed RNA were isolated by centrifugation through a sucrose cushion. RNA was extracted, ribosomal RNA was removed using Illumina's RiboZero kit, and remaining RNA was gel purified to select fragments 25-34 nt (PRRSV-1-infected samples, CHX-pre-treated PRRSV-2- or mock-infected samples, and non-CHX-pre-treated PRRSV-2- or mock-infected 9 hpi replicate one samples) or 19-34 nt long (all other samples). Fragments were cloned into adapters based on the TruSeq small RNA adapters. For all PRRSV-2-infected (or mock-infected) libraries, adapters with an additional seven random nucleotides at the 5′-end of the 3′-adapter and the 3′-end of the 5′-adapter were used. For PRRSV-1 replicate one, no random nucleotides were present on the adapters, and for PRRSV-1 replicate two, 14 random nucleotides were present at the 5′-end of the 3′-adapter. Libraries were sequenced on the Illumina NextSeq 500 platform as a single-end run. Non-CHX-pre-treated PRRSV-2-infected 9 hpi replicate two libraries were uploaded under a separate accession number due to differences in the size selection and sequencing protocol - see associated paired-end entry. Note that sample nomeclature (including replicate numbers) is consistent between this and the two related accessions, and RiboSeq libraries are matched with RNASeq libraries, which were prepared from the same lysate. The noCHX_Ribo_9hpi_mock_3 library is deliberately absent as this was a poor quality library.

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