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Post by jontrip247 on Nov 15, 2015 16:06:51 GMT -6
Cucumovirus
Quick recap:
Cucumber moasic virus
-tripartite ssRNA (+) genome that is non-enveloped and spherical with a T=3 icosahedral symmetry
-It's tripartite genomic RNAs are packaged into separate particles requiring multiple particles for infection.
-Cucumovirus is found globally and has a broad host range.
-Transmission occurs via aphids.
-There are 5 ORFs that encode for viral replicase, suppressor of post-transcriptional gene silencing, MP and CP
1) Please discuss the critical genome evolutionary models that apply to your assigned virus genus.
2) How do these models inform us about host range, genetic drift.
3) how can this information be used to develop control strategies for disease.
Analysis of each Cucumovirus RNA reveled a unique evolutionary history of each RNA. This is reported as an indication that reassortment has been a major influential factor in the evolution of this virus. The ability to use reassortment provides opportunity to achieve greater diversity during mixed infections that occur in plant and within the insect vector. For example: The CP and 2a were found to be more susceptible to mutations making their evolutionary history more diverse. This isn't too surprising when considering the virus has 2 separate hosts (insect/plant). The 3a ORF is involved in viral movement and interaction with plasmodesmata, which would limit mutations/evolution of this protein. This is due to 3a's intimate interaction with the host and being critical for establishing infection/propagation. With each RNA having its own evolutionary history, trying to pin-point one specific model or origin can be difficult to impossible.
It would seem that this virus has evolved with its hosts, which is more commonly seen with DNA viruses. But then one could ask if it branched from the plant to the insect or from the insect to the plant. The most likely is that it originated in the plant and over time developed the ability to enter the insect. Also, this virus has evolved by taking advantage of other viral particles and incorporating them to its benefit through reassortment or as discussed in class "modular evolution." This allowed for greater host diversity. Moving forward, it would be beneficial to identify all mechanisms involved in reassortment so that they might be disrupted thereby preventing its ability to evolve to selective pressures.
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Post by dulanjani on Nov 19, 2015 9:32:40 GMT -6
CucumovirusQuick recap:
Cucumber moasic virus -tripartite ssRNA (+) genome that is non-enveloped and spherical with a T=3 icosahedral symmetry -It's tripartite genomic RNAs are packaged into separate particles requiring multiple particles for infection.
-Cucumovirus is found globally and has a broad host range. -Transmission occurs via aphids. -There are 5 ORFs that encode for viral replicase, suppressor of post-transcriptional gene silencing, MP and CP
1) Please discuss the critical genome evolutionary models that apply to your assigned virus genus.
2) How do these models inform us about host range, genetic drift.
3) how can this information be used to develop control strategies for disease.
Analysis of each Cucumovirus RNA reveled a unique evolutionary history of each RNA. This is reported as an indication that reassortment has been a major influential factor in the evolution of this virus. The ability to use reassortment provides opportunity to achieve greater diversity during mixed infections that occur in plant and within the insect vector. For example: The CP and 2a were found to be more susceptible to mutations making their evolutionary history more diverse. This isn't too surprising when considering the virus has 2 separate hosts (insect/plant). The 3a ORF is involved in viral movement and interaction with plasmodesmata, which would limit mutations/evolution of this protein. This is due to 3a's intimate interaction with the host and being critical for establishing infection/propagation. With each RNA having its own evolutionary history, trying to pin-point one specific model or origin can be difficult to impossible. It would seem that this virus has evolved with its hosts, which is more commonly seen with DNA viruses. But then one could ask if it branched from the plant to the insect or from the insect to the plant. The most likely is that it originated in the plant and over time developed the ability to enter the insect. Also, this virus has evolved by taking advantage of other viral particles and incorporating them to its benefit through reassortment or as discussed in class "modular evolution." This allowed for greater host diversity. Moving forward, it would be beneficial to identify all mechanisms involved in reassortment so that they might be disrupted thereby preventing its ability to evolve to selective pressures. Thank you for the information Jon Do you know anything about how CMV evolution can be effected by CMV satellite RNA? Also do you know anything about having narrow genetic bottle necks could lead to have less fit variants in CMV populations? So what would be the possible reasons to have eliminate less fit individuals? Is it always environmental selection or could there be any other reason? |
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Post by omararias on Nov 20, 2015 23:31:46 GMT -6
CucumovirusQuick recap:
Cucumber moasic virus -tripartite ssRNA (+) genome that is non-enveloped and spherical with a T=3 icosahedral symmetry -It's tripartite genomic RNAs are packaged into separate particles requiring multiple particles for infection.
-Cucumovirus is found globally and has a broad host range. -Transmission occurs via aphids. -There are 5 ORFs that encode for viral replicase, suppressor of post-transcriptional gene silencing, MP and CP
1) Please discuss the critical genome evolutionary models that apply to your assigned virus genus.
2) How do these models inform us about host range, genetic drift.
3) how can this information be used to develop control strategies for disease.
Analysis of each Cucumovirus RNA reveled a unique evolutionary history of each RNA. This is reported as an indication that reassortment has been a major influential factor in the evolution of this virus. The ability to use reassortment provides opportunity to achieve greater diversity during mixed infections that occur in plant and within the insect vector. For example: The CP and 2a were found to be more susceptible to mutations making their evolutionary history more diverse. This isn't too surprising when considering the virus has 2 separate hosts (insect/plant). The 3a ORF is involved in viral movement and interaction with plasmodesmata, which would limit mutations/evolution of this protein. This is due to 3a's intimate interaction with the host and being critical for establishing infection/propagation. With each RNA having its own evolutionary history, trying to pin-point one specific model or origin can be difficult to impossible. It would seem that this virus has evolved with its hosts, which is more commonly seen with DNA viruses. But then one could ask if it branched from the plant to the insect or from the insect to the plant. The most likely is that it originated in the plant and over time developed the ability to enter the insect. Also, this virus has evolved by taking advantage of other viral particles and incorporating them to its benefit through reassortment or as discussed in class "modular evolution." This allowed for greater host diversity. Moving forward, it would be beneficial to identify all mechanisms involved in reassortment so that they might be disrupted thereby preventing its ability to evolve to selective pressures. Nice information Jon, please I have some questions, from what you have read is there special feature in the sequence of the CP and 2a regions, that could have led them to be more susceptible to mutations?, or do you think that the susceptibility was only due to host factors, or both? Thanks. |
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Post by jontrip247 on Nov 21, 2015 2:40:17 GMT -6
Omar,
I couldn't find the exact answer for your question but it would seem that because the CP and 2a are not directly tied to virus-host interactions they can more freely tolerate mutations. In other words, if the gene of interest required a specific relationship with a host gene, any alteration might be detrimental.
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Post by jontrip247 on Nov 21, 2015 2:51:02 GMT -6
Dj, Good question and thanks for asking. You got me thinking of something I never considered. It would seem that satellite RNAs contribute greatly to genetic diversification. Of course with the introduction of a lot of diversity/mutation you get a feedback of negative selection. Over time, I'd say that satellites play a critical role in CMV evolution and fitness. www.ncbi.nlm.nih.gov/pmc/articles/PMC238009/ |
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Post by omararias on Nov 22, 2015 13:27:13 GMT -6
Omar, I couldn't find the exact answer for your question but it would seem that because the CP and 2a are not directly tied to virus-host interactions they can more freely tolerate mutations. In other words, if the gene of interest required a specific relationship with a host gene, any alteration might be detrimental. Ok, thank you so much. |
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Post by gabriela on Nov 22, 2015 21:07:39 GMT -6
CucumovirusQuick recap:
Cucumber moasic virus -tripartite ssRNA (+) genome that is non-enveloped and spherical with a T=3 icosahedral symmetry -It's tripartite genomic RNAs are packaged into separate particles requiring multiple particles for infection.
-Cucumovirus is found globally and has a broad host range. -Transmission occurs via aphids. -There are 5 ORFs that encode for viral replicase, suppressor of post-transcriptional gene silencing, MP and CP
1) Please discuss the critical genome evolutionary models that apply to your assigned virus genus.
2) How do these models inform us about host range, genetic drift.
3) how can this information be used to develop control strategies for disease.
Analysis of each Cucumovirus RNA reveled a unique evolutionary history of each RNA. This is reported as an indication that reassortment has been a major influential factor in the evolution of this virus. The ability to use reassortment provides opportunity to achieve greater diversity during mixed infections that occur in plant and within the insect vector. For example: The CP and 2a were found to be more susceptible to mutations making their evolutionary history more diverse. This isn't too surprising when considering the virus has 2 separate hosts (insect/plant). The 3a ORF is involved in viral movement and interaction with plasmodesmata, which would limit mutations/evolution of this protein. This is due to 3a's intimate interaction with the host and being critical for establishing infection/propagation. With each RNA having its own evolutionary history, trying to pin-point one specific model or origin can be difficult to impossible. It would seem that this virus has evolved with its hosts, which is more commonly seen with DNA viruses. But then one could ask if it branched from the plant to the insect or from the insect to the plant. The most likely is that it originated in the plant and over time developed the ability to enter the insect. Also, this virus has evolved by taking advantage of other viral particles and incorporating them to its benefit through reassortment or as discussed in class "modular evolution." This allowed for greater host diversity. Moving forward, it would be beneficial to identify all mechanisms involved in reassortment so that they might be disrupted thereby preventing its ability to evolve to selective pressures. Segmented genomes of RNA viruses are thought to evolve and be maintained in analogy to sexual recombination and reassortment in eukaryotic systems. If reassortment among genomes is an important event in cucumoviral evolution, researches have suggested that if such events occurred they should be detectable among extant viruses. Phylogenetic analyses of cucumoviruses have been performed using aligned amino acid sequences. The results have revealed different relationships among species when the three genomic segments were compared, these results have suggested that reassortment events have given rise to extant forms. In addition, studies have also described a cucumovirus isolate that is composed of genomic segments from two distinct viral species. Results have showed reassortment events may provide a mechanism for speciation in cucumoviruses. |
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