scholarly journals Genetic analysis of maize streak virus isolates from Uganda reveals widespread distribution of a recombinant variant

2007 ◽  
Vol 88 (11) ◽  
pp. 3154-3165 ◽  
Author(s):  
Betty E. Owor ◽  
Darren P. Martin ◽  
Dionne N. Shepherd ◽  
Richard Edema ◽  
Adérito L. Monjane ◽  
...  

Maize streak virus (MSV) contributes significantly to the problem of extremely low African maize yields. Whilst a diverse range of MSV and MSV-like viruses are endemic in sub-Saharan Africa and neighbouring islands, only a single group of maize-adapted variants – MSV subtypes A1–A6 – causes severe enough disease in maize to influence yields substantially. In order to assist in designing effective strategies to control MSV in maize, a large survey covering 155 locations was conducted to assess the diversity, distribution and genetic characteristics of the Ugandan MSV-A population. PCR–restriction fragment-length polymorphism analyses of 391 virus isolates identified 49 genetic variants. Sixty-two full-genome sequences were determined, 52 of which were detectably recombinant. All but two recombinants contained predominantly MSV-A1-like sequences. Of the ten distinct recombination events observed, seven involved inter-MSV-A subtype recombination and three involved intra-MSV-A1 recombination. One of the intra-MSV-A1 recombinants, designated MSV-A1UgIII, accounted for >60 % of all MSV infections sampled throughout Uganda. Although recombination may be an important factor in the emergence of novel geminivirus variants, it is demonstrated that its characteristics in MSV are quite different from those observed in related African cassava-infecting geminivirus species.

Plant Disease ◽  
2006 ◽  
Vol 90 (12) ◽  
pp. 1485-1489 ◽  
Author(s):  
S. Mawere ◽  
V. Vincent ◽  
J. De Meyer ◽  
K. V. Pixley

Maize streak is the most widespread and important disease of maize in sub-Saharan Africa. Maize streak virus (MSV)-resistant maize germ plasm is available in several countries, but little is known about the stability of its resistance to MSV strains that may differ from one region to another. We used four maize inbred lines (CML312, CML206, CML216, and MSR) known to differ widely for their resistance to MSV in Harare, and evaluated their resistance to 20 MSV isolates collected from the wild during 2 years at locations across Zimbabwe. Maize streak development and symptom severity were evaluated in replicated greenhouse experiments using artificial inoculation via viruliferous leafhoppers. All 20 MSV isolates induced maize streak symptoms on moderately and highly susceptible genotypes by about 1 week after inoculation (WAI). Differences among isolates for severity of early maize streak symptoms were ephemeral, and resistance was accurately differentiated by all isolates by 3 to 4 WAI. Differences in final maize streak symptom scores induced by the isolates were statistically significant, but differed only by a maximum of 7% in 1999 and 19% in 2000. Although genotype, isolate, and genotype by isolate effects for maize streak symptom scores were significant (P < 0.01), relative MSV resistance of the genotypes was consistently ranked by all 20 MSV isolates.


Author(s):  
Salwa A. Musa ◽  
Areej A. Ibrahim ◽  
Samar S. Hassan ◽  
Matthew B Johnson ◽  
Asmahan T. Basheer ◽  
...  

Abstract Background Fanconi-Bickel syndrome (FBS) is a rare condition of carbohydrate metabolism, caused by a recessive defect in the facilitative glucose transporter GLUT2 encoded by the SLC2A2 gene and characterized by a wide spectrum of phenotypical features. There is a paucity of reported data on FBS from Sub-Saharan Africa. Here, we describe the clinical, biochemical and genetic characteristics of our patients with FBS from Sudan, a country with a high consanguinity rate. Patients & methods Eleven patients from ten unrelated Sudanese families were included. Clinical & biochemical data were documented and imaging studies done including bone survey and abdominal ultrasound. Liver biopsy was done to confirm the pathological diagnosis in 45% of cases and molecular genetics was performed through contribution with the Exeter genomics laboratory for ten patients. Results Reported consanguinity was 70% among our patients. Growth was significantly impaired at presentation with mean weights of (-5.3 ± 1.8) SD and heights (-5.4 ± 2.5) SD. Severe chest deformity was present in (27%) and all patients showed features of rickets at presentation. Three patients had neonatal diabetes requiring insulin therapy of which one has been reported before. Six families lost undiagnosed siblings with similar clinical presentations. We identified a total of four homozygous pathogenic SLC2A2 variants in our patients, one of whom had a novel mutation. Conclusions FBS is not uncommon in Sudan where there is a high rate of consanguinity. Many cases are likely missed because of variable presentation and lack of public and professionals’ awareness. This is the first series to describe this condition from Sub-Saharan Africa.


Author(s):  
Daniel Kepple ◽  
Alfred Hubbard ◽  
Musab M Ali ◽  
Beka R Abargero ◽  
Karen Lopez ◽  
...  

Abstract Plasmodium vivax malaria was thought to be rare in Africa, but an increasing number of P. vivax cases reported across Africa and in Duffy-negative individuals challenges this conventional dogma. The genetic characteristics of P. vivax in Duffy-negative infections, the transmission of P. vivax in East Africa, and the impact of environments on transmission remain largely unknown. This study examined genetic and transmission features of P. vivax from 107 Duffy-negative and 305 Duffy-positive individuals in Ethiopia and Sudan. No clear genetic differentiation was found in P. vivax between the two Duffy groups, indicating between-host transmission. P. vivax from Ethiopia and Sudan showed similar genetic clusters, except samples from Khartoum, possibly due to distance and road density that inhibited parasite gene flow. This study is the first to show that P. vivax can transmit to and from Duffy-negative individuals and provides critical insights into the spread of P. vivax in sub-Saharan Africa.


Intervirology ◽  
1989 ◽  
Vol 30 (2) ◽  
pp. 96-101 ◽  
Author(s):  
Ralph Kirby ◽  
Beverley A. Clarke ◽  
Edward P. Rybicki

Virology ◽  
2001 ◽  
Vol 288 (2) ◽  
pp. 247-255 ◽  
Author(s):  
D.P. Martin ◽  
J.A. Willment ◽  
R. Billharz ◽  
R. Velders ◽  
B. Odhiambo ◽  
...  

2011 ◽  
Vol 92 (10) ◽  
pp. 2458-2465 ◽  
Author(s):  
Betty E. Owor ◽  
Darren P. Martin ◽  
Edward P. Rybicki ◽  
Jennifer A. Thomson ◽  
Marion E. Bezuidenhout ◽  
...  

Maize streak disease, caused by the A strain of the African endemic geminivirus, maize streak mastrevirus (MSV-A), threatens the food security and livelihoods of subsistence farmers throughout sub-Saharan Africa. Using a well-established transient expression assay, this study investigated the potential of a spliceable-intron hairpin RNA (hpRNA) approach to interfere with MSV replication. Two strategies were explored: (i) an inverted repeat of a 662 bp region of the MSV replication-associated protein gene (rep), which is essential for virus replication and is therefore a good target for post-transcriptional gene silencing; and (ii) an inverted repeat of the viral long intergenic region (LIR), considered for its potential to trigger transcriptional silencing of the viral promoter region. After co-bombardment of cultured maize cells with each construct and an infectious partial dimer of the cognate virus genome (MSV-Kom), followed by viral replicative-form-specific PCR, it was clear that, whilst the hairpin rep construct (pHPrepΔI662) completely inhibited MSV replication, the LIR hairpin construct was ineffective in this regard. In addition, pHPrepΔI662 inhibited or reduced replication of six MSV-A genotypes representing the entire breadth of known MSV-A diversity. Further investigation by real-time PCR revealed that the pHPrepΔI662 inverted repeat was 22-fold more effective at reducing virus replication than a construct containing the sense copy, whilst the antisense copy had no effect on replication when compared with the wild type. This is the first indication that an hpRNA strategy targeting MSV rep has the potential to protect transgenic maize against diverse MSV-A genotypes found throughout sub-Saharan Africa.


Author(s):  
Sophie Dulucq

In the second half of the 19th century, French imperial expansion in the south of the Sahara led to the control of numerous African territories. The colonial rule France imposed on a diverse range of cultural groups and political entities brought with it the development of equally diverse inquiry and research methodologies. A new form of scholarship, africanisme, emerged as administrators, the military, and amateur historians alike began to gather ethnographic, linguistic, judicial, and historical information from the colonies. Initially, this knowledge was based on expertise gained in the field and reflected the pragmatic concerns of government rather than clear, scholarly, interrogation in line with specific scientific disciplines. Research was thus conducted in many directions, contributing to the emergence of the so-called colonial sciences. Studies by Europeans scholars, such as those carried out by Maurice Delafosse and Charles Monteil, focused on West Africa’s past. In so doing, the colonial context of the late 19th century reshaped the earlier orientalist scholarship tradition born during the Renaissance, which had formerly produced quality research about Africa’s past, for example, about medieval Sudanese states. This was achieved through the study of Arabic manuscripts and European travel narratives. In this respect, colonial scholarship appears to have perpetuated the orientalist legacy, but in fact, it transformed the themes, questions, and problems historians raised. In the first instance, histoire coloniale (colonial history) focused the history of European conquests and the interactions between African societies and their colonizers. Between 1890 and 1920 a network of scientists, including former colonial administrators, struggled to institutionalize colonial history in metropolitan France. Academic positions were established at the Sorbonne and the Collège de France. Meanwhile, research institutions were created in French West Africa (Afrique Occidentale Française [AOF]), French Equatorial Africa (Afrique Équatoriale Française [AEF]), and Madagascar between 1900 and the 1930s. Yet, these imperial and colonial concerns similarly coincided with the rise of what was then known as histoire indigène (native history) centered on the precolonial histories of African societies. Through this lens emerged a more accurate vision of the African past, which fundamentally challenged the common preconception that the continent had no “history.” This innovative knowledge was often co-produced by African scholars and intellectuals. After the Second World War, interest in colonial history started to wane, both from an intellectual and a scientific point of view. In its place, the history of sub-Saharan Africa gained popularity and took root in French academic institutions. Chairs of African history were created at the Sorbonne in 1961 and 1964, held by Raymond Mauny and Hubert Deschamps, respectively, and in 1961 at the École Pratique des Hautes Études, fulfilled by Henri Brunschwig. African historians, who were typically trained in France, began to challenge the existing European scholarship. As a result, some of the methods and sources that had been born in the colonial era, were adopted for use by a new generation of historians, whose careers blossomed after the independences.


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