scholarly journals Functional Characterization of Adaptive Mutations during the West African Ebola Virus Outbreak

2016 ◽  
Vol 91 (2) ◽  
Author(s):  
Erik Dietzel ◽  
Gordian Schudt ◽  
Verena Krähling ◽  
Mikhail Matrosovich ◽  
Stephan Becker
Keyword(s):  
West Africa ◽  
Receptor Binding ◽  
Ebola Virus ◽  
Viral Proteins ◽  
West African ◽  
Surface Glycoprotein ◽  
Viral Transcription ◽  
Receptor Binding Domain ◽  
The West ◽  
Transcription And Replication

ABSTRACT The Ebola virus (EBOV) outbreak in West Africa started in December 2013, claimed more than 11,000 lives, threatened to destabilize a whole region, and showed how easily health crises can turn into humanitarian disasters. EBOV genomic sequences of the West African outbreak revealed nonsynonymous mutations, which induced considerable public attention, but their role in virus spread and disease remains obscure. In this study, we investigated the functional significance of three nonsynonymous mutations that emerged early during the West African EBOV outbreak. Almost 90% of more than 1,000 EBOV genomes sequenced during the outbreak carried the signature of three mutations: a D759G substitution in the active center of the L polymerase, an A82V substitution in the receptor binding domain of surface glycoprotein GP, and an R111C substitution in the self-assembly domain of RNA-encapsidating nucleoprotein NP. Using a newly developed virus-like particle system and reverse genetics, we found that the mutations have an impact on the functions of the respective viral proteins and on the growth of recombinant EBOVs. The mutation in L increased viral transcription and replication, whereas the mutation in NP decreased viral transcription and replication. The mutation in the receptor binding domain of the glycoprotein GP improved the efficiency of GP-mediated viral entry into target cells. Recombinant EBOVs with combinations of the three mutations showed a growth advantage over the prototype isolate Makona C7 lacking the mutations. This study showed that virus variants with improved fitness emerged early during the West African EBOV outbreak. IMPORTANCE The dimension of the Ebola virus outbreak in West Africa was unprecedented. Amino acid substitutions in the viral L polymerase, surface glycoprotein GP, and nucleocapsid protein NP emerged, were fixed early in the outbreak, and were found in almost 90% of the sequences. Here we showed that these mutations affected the functional activity of viral proteins and improved viral growth in cell culture. Our results demonstrate emergence of adaptive changes in the Ebola virus genome during virus circulation in humans and prompt further studies on the potential role of these changes in virus transmissibility and pathogenicity.

scholarly journals Promoting research to improve maternal, neonatal, infant and adolescent health in West Africa: the role of the West African Health Organisation

2017 ◽  
Vol 15 (S1) ◽  
Author(s):  
Issiaka Sombie ◽  
Aissa Bouwayé ◽  
Yves Mongbo ◽  
Namoudou Keita ◽  
Virgil Lokossou ◽  
...  
Keyword(s):  
West Africa ◽  
Adolescent Health ◽  
West African ◽  
The West ◽  
African Health

A curious case of nematode parasitism in a West African Hadada, Gevonticus hagedash

1945 ◽  
Vol 21 (2-3) ◽  
pp. 99-103 ◽  
Author(s):  
Phyllis A. Clapham
Keyword(s):  
Small Intestine ◽  
West Africa ◽  
West Coast ◽  
West African ◽  
The West ◽  
The Family ◽  
Nematode Parasitism

In the following article is described an interesting parasitic condition which is difficult to interpret. The small intestine of an Hadada, Geronticus hagedash, was brought back from the West Coast of Africa by Major T. A. Cockburn, M.D., R.A.M.C, who kindly passed it to me for further examination. The bird is a member of the family Plataleidae, living in wooded districts in West Africa in the neighbourhood of water and feeding on invertebrates, mainly annelids and small crustaceans which it finds at the bottom of ponds and streams in the mud.

scholarly journals On What Scale Can We Predict the Agronomic Onset of the West African Monsoon?

2016 ◽  
Vol 144 (4) ◽  
pp. 1571-1589 ◽  
Author(s):  
Rory G. J. Fitzpatrick ◽  
Caroline L. Bain ◽  
Peter Knippertz ◽  
John H. Marsham ◽  
Douglas J. Parker
Keyword(s):  
West Africa ◽  
Noise Analysis ◽  
West African Monsoon ◽  
West African ◽  
New Method ◽  
The West ◽  
African Monsoon ◽  
Spatial Consistency ◽  
Local Stakeholders ◽  
Local Rainfall

Abstract Accurate prediction of the commencement of local rainfall over West Africa can provide vital information for local stakeholders and regional planners. However, in comparison with analysis of the regional onset of the West African monsoon, the spatial variability of the local monsoon onset has not been extensively explored. One of the main reasons behind the lack of local onset forecast analysis is the spatial noisiness of local rainfall. A new method that evaluates the spatial scale at which local onsets are coherent across West Africa is presented. This new method can be thought of as analogous to a regional signal against local noise analysis of onset. This method highlights regions where local onsets exhibit a quantifiable degree of spatial consistency (denoted local onset regions or LORs). It is found that local onsets exhibit a useful amount of spatial agreement, with LORs apparent across the entire studied domain; this is in contrast to previously found results. Identifying local onset regions and understanding their variability can provide important insight into the spatial limit of monsoon predictability. While local onset regions can be found over West Africa, their size is much smaller than the scale found for seasonal rainfall homogeneity. A potential use of local onset regions is presented that shows the link between the annual intertropical front progression and local agronomic onset.

Paleomagnetism of the ~860 Ma Manso dyke swarm, West Africa: implications for the assembly of Rodinia

2021 ◽  
Author(s):  
Paul Yves Jean Antonio ◽  
Lenka Baratoux ◽  
Ricardo Ivan Ferreira Trindade ◽  
Sonia Rousse ◽  
Anani Ayite ◽  
...  
Keyword(s):  
West Africa ◽  
West African ◽  
Dyke Swarm ◽  
Jigsaw Puzzle ◽  
The West ◽  
West African Craton ◽  
Contact Test ◽  
Fine Grained ◽  
Paleomagnetic Pole ◽  
Coarse To Fine

<p>The West African Craton (WAC) is one of the major cratons in the Rodinia jigsaw puzzle (~1000–750 Ma). In the Rodinian models, the position of West Africa is mainly constrained by the assumption that it had been a partner of Amazonia since the Paleoproterozoic. Unfortunately, no paleomagnetic data are available for these cratons when the Rodina supercontinent is considered tectonically stable (~1000-750 Ma). Thus, every new reliable paleomagnetic pole for the West African Craton during the Neoproterozoic times is of paramount importance to constrain its position and testing the Rodinia models. In this study we present a combined paleomagnetic and geochronological investigation for the Manso dyke swarm in the Leo-Man Shield, southern West Africa (Ghana). The ~860 Ma emplacement age for the NNW-trending Manso dykes is thus well-constrained by two new U-Pb apatite ages of 857.2 ± 8.5 Ma and 855 ± 16 Ma, in agreement with baddeleyite data. Remanence of these coarse-to-fine grained dolerite dykes is carried by stable single to pseudo-single domain (SD-PSD) magnetite. A positive baked-contact test, associated to a positive reversal test (Class-C), support the primary remanence obtained for these dykes (13 sites). Moreover, our new paleomagnetic dataset satisfy all the seven R-criteria (R=7). The ~860 Ma Manso pole can thus be considered as the first key Tonian paleomagnetic pole for West Africa. We propose that the West Africa-Baltica-Amazonia-Congo-São Francisco were associated in a long-lived WABAMGO juxtaposition (~1100–800 Ma).</p><p><strong>Keywords:</strong> West Africa, Neoproterozoic, Tonian, Rodinia, paleomagnetism.</p><p> </p>

A New Lautoconus Species Radiation from Gambia, West Africa

The Festivus ◽  
2018 ◽  
Vol 50 (3) ◽  
pp. 164-172
Author(s):  
Edward Petuch ◽  
David Berschauer
Keyword(s):  
New Species ◽  
West Africa ◽  
River Mouth ◽  
Sympatric Species ◽  
West African ◽  
The West ◽  
Species Radiation ◽  
West African Coast ◽  
African Coast ◽  
Reef Fauna

Six sympatric species of the cone shell genus Lautoconus Monterosato, 1923 have been discovered on an isolated rock reef near the Gambia River Mouth, Gambia, West Africa. Of these, four were found to be new to science and, together, they represent a previously unknown Gambian endemic species radiation. These include: Lautoconus fernandi new species, L. gambiensis new species, L. rikae new species, and L. wolof new species. The poorly-known Gambian endemic cone, Lautoconus orri (Ninomiya and da Motta, 1982) was also found to be a component of the rock reef fauna, as was the wide-ranging L. guinaicus (Hwass, 1792) (Senegal to Ghana). The Gambian cluster of sibling species represents the farthest-south separate radiation of Lautoconus known from the West African coast.

scholarly journals Sensitivity study of the regional climate model RegCM4 to different convective schemes over West Africa

2018 ◽  
Vol 9 (4) ◽  
pp. 1261-1278 ◽  
Author(s):  
Brahima Koné ◽  
Arona Diedhiou ◽  
N'datchoh Evelyne Touré ◽  
Mouhamadou Bamba Sylla ◽  
Filippo Giorgi ◽  
...  
Keyword(s):  
West Africa ◽  
Land Surface ◽  
West African ◽  
Cold Bias ◽  
The West ◽  
Land Surface Scheme ◽  
African Climate ◽  
Sensitivity Studies ◽  
Surface Scheme ◽  
Convective Scheme

Abstract. The latest version of RegCM4 with CLM4.5 as a land surface scheme was used to assess the performance and sensitivity of the simulated West African climate system to different convection schemes. The sensitivity studies were performed over the West African domain from November 2002 to December 2004 at a spatial resolution of 50 km × 50 km and involved five convective schemes: (i) Emanuel; (ii) Grell; (iii) Emanuel over land and Grell over ocean (Mix1); (iv) Grell over land and Emanuel over ocean (Mix2); and (v) Tiedtke. All simulations were forced with ERA-Interim data. Validation of surface temperature at 2 m and precipitation were conducted using data from the Climate Research Unit (CRU), Global Precipitation Climatology Project (GPCP) and the Tropical Rainfall Measurement Mission (TRMM) during June to September (rainy season), while the simulated atmospheric dynamic was compared to ERA-Interim data. It is worth noting that the few previous similar sensitivity studies conducted in the region were performed using BATS as a land surface scheme and involved less convective schemes. Compared with the previous version of RegCM, RegCM4-CLM also shows a general cold bias over West Africa whatever the convective scheme used. This cold bias is more reduced when using the Emanuel convective scheme. In terms of precipitation, the dominant feature in model simulations is a dry bias that is better reduced when using the Emanuel convective scheme. Considering the good performance with respect to a quantitative evaluation of the temperature and precipitation simulations over the entire West African domain and its subregions, the Emanuel convective scheme is recommended for the study of the West African climate system.

The Garvey Movement in British West Africa

1980 ◽  
Vol 21 (1) ◽  
pp. 105-117 ◽  
Author(s):  
R. L. Okonkwo
Keyword(s):  
West Africa ◽  
West African ◽  
Colonial Rule ◽  
Long Term Effects ◽  
The West ◽  
Universal Negro Improvement Association ◽  
History Of ◽  
American Blacks ◽  
Garvey Movement ◽  
African Nationalism

The paper seeks to present new information concerning the activities of the West African branches of Marcus Garvey's Universal Negro Improvement Association and African Communities League. The author has included biographical profiles of the British West African Garveyites to integrate the Garvey movement into the history of West African nationalism and Pan-Africanism.It is argued that Garveyism was welcomed in British West Africa by the older cultural nationalists who saw Garveyism as an extension of Blyden's ideas. Pan-African sentiments of racial unity and solidarity of African and American blacks, pride in the history of the race, and self-help projects had wide circulation in West Africa from the latter part of the nineteenth century, as a result of Blyden's influence. Joining the branches of the U.N.I.A. was a practical demonstration of a long-standing commitment to cultural and racial nationalism among the West African elite.The Garvey movement also marked the beginning of a new era in West African nationalism. Garvey's radical pronouncements on freeing Africa from colonial rule were unacceptable to the older cultural nationalists who dominated the Garvey groups. They disavowed any interest in organizing a central nation for the race. However, Garvey's ideas may have had long-term effects. By the 1930s the idea of independence from colonial rule seemed more attractive to the West African nationalists. Garvey was one of the first to speak out boldly for freedom from colonialism.The concrete achievements of the West African branches of the U.N.I.A. were small indeed. Nigeria had the most Garveyite activity in British West Africa. There was an agent for the Black Star Line in Lagos and a branch of the U.N.I.A. and A.C.L. The Gold Coast had the least Garveyite activity, probably because of their involvement in the National Congress of British West Africa and also because of their more critical attitude towards co-operation with American blacks. They believed that Africans were best qualified to lead any joint efforts for intra-racial co-operation.

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