9 research outputs found
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Recombinant Goose Circoviruses Circulating in Domesticated and Wild Geese in Poland
Circoviruses are circular single-stranded DNA (ssDNA) viruses that infect a variety of animals, both domestic and wild. Circovirus infection in birds is associated with immunosuppression and this in turn predisposes the infected animals to secondary infections that can lead to mortality. Farmed geese (Anser anser) in many parts of the world are infected with circoviruses. The majority of the current genomic information for goose circoviruses (GoCVs) (n = 40) are from birds sampled in China and Taiwan, and only two genome sequences are available from Europe (Germany and Poland). In this study, we sampled 23 wild and 19 domestic geese from the GopĆo Lake area in Poland. We determined the genomes of GoCV from 21 geese; 14 domestic Greylag geese (Anser anser), three wild Greylag geese (A. anser), three bean geese (A. fabalis), and one white fronted goose (A. albifrons). These genomes share 83â95% nucleotide pairwise identities with previously identified GoCV genomes, most are recombinants with exchanged fragment sizes up to 50% of the genome. Higher diversity levels can be seen within the genomes from domestic geese compared with those from wild geese. In the GoCV capsid protein (cp) and replication associated protein (rep) gene sequences we found that episodic positive selection appears to largely mirror those of beak and feather disease virus and pigeon circovirus. Analysis of the secondary structure of the ssDNA genome revealed a conserved stem-loop structure with the G-C rich stem having a high degree of negative selection on these nucleotides
Symptom evolution following the emergence of maize streak virus
For pathogens infecting single host species evolutionary trade-offs have previously
been demonstrated between pathogen-induced mortality rates and transmission rates. It remains
unclear, however, how such trade-offs impact sub-lethal pathogen-inflicted damage, and whether
these trade-offs even occur in broad host-range pathogens. Here, we examine changes over the
past 110 years in symptoms induced in maize by the broad host-range pathogen, maize streak virus
(MSV). Specifically, we use the quantified symptom intensities of cloned MSV isolates in
differentially resistant maize genotypes to phylogenetically infer ancestral symptom intensities and
check for phylogenetic signal associated with these symptom intensities. We show that whereas
symptoms reflecting harm to the host have remained constant or decreased, there has been an
increase in how extensively MSV colonizes the cells upon which transmission vectors feed
Geometagenomics illuminates the impact of agriculture on the distribution and prevalence of plant viruses at the ecosystem scale
Disease emergence events regularly result from human activities such as agriculture, which
frequently brings large populations of genetically uniform hosts into contact with potential
pathogens. Although viruses cause nearly 50% of emerging plant diseases, there is little systematic
information about virus distribution across agro-ecological interfaces and large gaps in understanding
of virus diversity in nature. Here we applied a novel landscape-scale geometagenomics
approach to examine relationships between agricultural land use and distributions of plantassociated
viruses in two Mediterranean-climate biodiversity hotspots (Western Cape region of
South Africa and RhĂŽne river delta region of France). In total, we analysed 1725 geo-referenced plant
samples collected over two years from 4.5 Ă 4.5 km2 grids spanning farmlands and adjacent
uncultivated vegetation. We found substantial virus prevalence (25.8â35.7%) in all ecosystems, but
prevalence and identified family-level virus diversity were greatest in cultivated areas, with some
virus families displaying strong agricultural associations. Our survey revealed 94 previously
unknown virus species, primarily from uncultivated plants. This is the first effort to systematically
evaluate plant-associated viromes across broad agro-ecological interfaces. Our findings indicate that
agriculture substantially influences plant virus distributions and highlight the extent of current
ignorance about the diversity and roles of viruses in nature
Recombinant Goose Circoviruses Circulating in Domesticated and Wild Geese in Poland
Circoviruses are circular single-stranded DNA (ssDNA) viruses that infect a variety of animals, both domestic and wild. Circovirus infection in birds is associated with immunosuppression and this in turn predisposes the infected animals to secondary infections that can lead to mortality. Farmed geese (Anser anser) in many parts of the world are infected with circoviruses. The majority of the current genomic information for goose circoviruses (GoCVs) (n = 40) are from birds sampled in China and Taiwan, and only two genome sequences are available from Europe (Germany and Poland). In this study, we sampled 23 wild and 19 domestic geese from the GopĆo Lake area in Poland. We determined the genomes of GoCV from 21 geese; 14 domestic Greylag geese (Anser anser), three wild Greylag geese (A. anser), three bean geese (A. fabalis), and one white fronted goose (A. albifrons). These genomes share 83â95% nucleotide pairwise identities with previously identified GoCV genomes, most are recombinants with exchanged fragment sizes up to 50% of the genome. Higher diversity levels can be seen within the genomes from domestic geese compared with those from wild geese. In the GoCV capsid protein (cp) and replication associated protein (rep) gene sequences we found that episodic positive selection appears to largely mirror those of beak and feather disease virus and pigeon circovirus. Analysis of the secondary structure of the ssDNA genome revealed a conserved stem-loop structure with the G-C rich stem having a high degree of negative selection on these nucleotides
How virulent are emerging maize-infecting mastreviruses?
International audienceMaize streak disease (MSD) is one of the most significant biotic constraints on the production of Africa's most important cereal crop. Until recently, the only virus known to cause severe MSD was the A-strain of maize streak virus (MSV/A), a member of the genus Mastrevirus, family Geminiviridae. However, over the past decade, two other mastreviruses, MSV/C and maize streak Reunion virus (MSRV), have been repeatedly found in the absence of MSV/A in maize plants displaying severe MSD symptoms. Here, we report on infectious clones of MSV/C and MSRV and test their ability to cause severe MSD symptoms. Although cloned MSV/C and MSRV genomes could cause systemic symptomatic infections in MSD-sensitive maize genotypes, these infections yielded substantially milder symptoms than those observed in the field. The MSV/C and MSRV isolates that we have examined are therefore unlikely to cause severe MSD on their own. Furthermore, mixed infections of MSRV and MSV/C with other mild MSV strains also consistently yielded mild MSD symptoms. It is noteworthy that MSRV produces distinctive striate symptoms in maize that are similar in pattern, albeit not in severity, to those seen in the field, showing that this virus may contribute to the severe MSD symptoms seen in the field. Therefore, despite not fulfilling Koch's postulates for MSV/C and MSRV as causal agents of severe MSD, we cannot exclude the possibility that these viruses could be contributing to currently emerging maize diseases
Recommended from our members
Symptom evolution following the emergence of maize streak virus.
For pathogens infecting single host species evolutionary trade-offs have previously been demonstrated between pathogen-induced mortality rates and transmission rates. It remains unclear, however, how such trade-offs impact sub-lethal pathogen-inflicted damage, and whether these trade-offs even occur in broad host-range pathogens. Here, we examine changes over the past 110 years in symptoms induced in maize by the broad host-range pathogen, maize streak virus (MSV). Specifically, we use the quantified symptom intensities of cloned MSV isolates in differentially resistant maize genotypes to phylogenetically infer ancestral symptom intensities and check for phylogenetic signal associated with these symptom intensities. We show that whereas symptoms reflecting harm to the host have remained constant or decreased, there has been an increase in how extensively MSV colonizes the cells upon which transmission vectors feed. This demonstrates an evolutionary trade-off between amounts of pathogen-inflicted harm and how effectively viruses position themselves within plants to enable onward transmission
Molecular characterization and prevalence of two capulaviruses: Alfalfa leaf curl virus from France and Euphorbia caput-medusae latent virus from South Africa
Little is known about the prevalence, diversity, evolutionary processes, genomic structures and population dynamics of viruses in the divergent geminivirus lineage known as the capulaviruses. We determined and analyzed full genome sequences of 13 Euphorbia caput-medusae latent virus (EcmLV) and 26 Alfalfa leaf curl virus (ALCV) isolates, and partial genome sequences of 23 EcmLV and 37 ALCV isolates. While EcmLV was asymptomatic in uncultivated southern African Euphorbia caput-medusae, severe alfalfa disease symptoms were associated with ALCV in southern France. The prevalence of both viruses exceeded 10% in their respective hosts. Besides using patterns of detectable negative selection to identify ORFs that are probably functionally expressed, we show that ALCV and EcmLV both display evidence of inter-species recombination and biologically functional genomic secondary structures. Finally, we show that whereas the EcmLV populations likely experience restricted geographical dispersion, ALCV is probably freely moving across the French Mediterranean region