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Topical news snippets about viruses that affect people.  And other things. Like Led Zeppelin. And zombies B-)
Curated by Ed Rybicki
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PLOS Pathogens: Plant Virus Ecology

PLOS Pathogens: Plant Virus Ecology | Virology News | Scoop.it

Viruses have generally been studied either as disease-causing infectious agents that have a negative impact on the host (most eukaryote-infecting viruses), or as tools for molecular biology (especially bacteria-infecting viruses, or phage). Virus ecology looks at the more complex issues of virus-host-environment interactions. For plant viruses this includes studies of plant virus biodiversity, including viruses sampled directly from plants and from a variety of other environments; how plant viruses impact species invasion; interactions between plants, viruses and insects; the large number of persistent viruses in plants that may have epigenetic effects; and viruses that provide a clear benefit to their plant hosts (mutualists). Plants in a non-agricultural setting interact with many other living entities such as animals, insects, and other plants, as well as their physical environment. Wild plants are almost always colonized by a number of microbes, including fungi, bacteria and viruses. Viruses may impact any of these interactions [1].

Ed Rybicki's insight:

Nice, reasoned review on something most human and animal virologists take no notice of whatsoever...B-)  OK, she does have "Plant Virus Biodiveristy" as her first heading, but hey, I misspelled my own name on my second paper when referring to my first!

 

The bottom line is that we notice plant viruses when they do things to our crop plants or companion plants - and not when they are in their natural (read: non-agricultural / horticultural) setting.  As Marilyn points out, plant viruses may interact with plant host, insect vector and humans - and with other pathogens and commensals and symbionts, making for a potentially VERY complex ecosystem.

 

Interestingly, "wild" plant viruses often cause persistent infections, and are efficiently transmitted vertically - and may even, as in the begomovirus-infected Abutilon, give rise to a pleasing phenotype that has resulted in spread, via cultivation, around the world.

 

The world needs more plant virologists.  It certainly has enough plant viruses!

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The subgenomic promoter of brome mosaic virus folds into a stem–loop structure capped by a pseudo-triloop that is structurally similar to the triloop of the genomic promoter

The subgenomic promoter of brome mosaic virus folds into a stem–loop structure capped by a pseudo-triloop that is structurally similar to the triloop of the genomic promoter | Virology News | Scoop.it

In brome mosaic virus, both the replication of the genomic (+)-RNA strands and the transcription of the subgenomic RNA are carried out by the viral replicase. The production of (−)-RNA strands is dependent on the formation of an AUA triloop in the stem–loop C (SLC) hairpin in the 3′-untranslated region of the (+)-RNA strands. Two alternate hypotheses have been put forward for the mechanism of subgenomic RNA transcription. One posits that transcription commences by recognition of at least four key nucleotides in the subgenomic promoter by the replicase. The other posits that subgenomic transcription starts by binding of the replicase to a hairpin formed by the subgenomic promoter that resembles the minus strand promoter hairpin SLC. In this study, we have determined the three-dimensional structure of the subgenomic promoter hairpin using NMR spectroscopy. The data show that the hairpin is stable at 30°C and that it forms a pseudo-triloop structure with a transloop base pair and a nucleotide completely excluded from the helix. The transloop base pair is capped by an AUA triloop that possesses an extremely well packed structure very similar to that of the AUA triloop of SLC, including the formation of a so-called clamped-adenine motif. The similarities of the NMR structures of the hairpins required for genomic RNA and subgenomic RNA synthesis show that the replicase recognizes structure rather than sequence-specific motifs in both promoters.

 

BMV!! I worked on bromoviruses in general and BMV in particular from 1977 to around 1985, and collected every paper on them - and especially the mol biol. It was always obvious, once the sequences were known, that origins of replication and the subgenomic promoter were not sequence-delimited - and now we see that it's a structure. Cool stuff!!

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