Role of nucleotide binding and GTPase domain dimerization in dynamin-like myxovirus resistance protein A for GTPase activation and antiviral activity

Myxovirus resistance (Mx) GTPases are induced by interferon and inhibit multiple viruses including influenza and human immunodeficiency viruses. They have the characteristic domain architecture of dynamin-related proteins with an amino-terminal GTPase (G) domain, a bundle signaling element, and a carboxy-terminal stalk responsible for self-assembly and effector functions. Human MxA (also called MX1) is expressed in the cytoplasm and is partly associated with membranes of the smooth endoplasmic reticulum (ER). It shows a protein concentration-dependent increase in GTPase activity, indicating regulation of GTP hydrolysis via G domain dimerization. Here, we characterized a panel of G domain mutants in MxA to clarify the role of GTP binding and the importance of the G domain interface for the catalytic and antiviral function of MxA. Residues in the catalytic center of MxA and the nucleotide itself were essential for G domain dimerization and catalytic activation. In pulldown experiments, MxA recognized Thogoto virus nucleocapsid proteins independently of nucleotide binding. However, both nucleotide binding and hydrolysis were required for the antiviral activity against Thogoto, influenza and La Crosse viruses. We further demonstrate that GTP binding facilitates formation of stable MxA assemblies associated with ER membranes, whereas nucleotide hydrolysis promotes dynamic redistribution of MxA from cellular membranes to viral targets. Our study highlights the role of nucleotide binding and hydrolysis for the intracellular dynamics of MxA during its antiviral action

The crystal structure of the Hazara virus nucleocapsid protein

Background: Hazara virus (HAZV) is a member of the Bunyaviridae family of segmented negative stranded RNA viruses, and shares the same serogroup as Crimean-Congo haemorrhagic fever virus (CCHFV). CCHFV is responsible for fatal human disease with a mortality rate approaching 30 %, which has an increased recent incidence within southern Europe. There are no preventative or therapeutic treatments for CCHFV-mediated disease, and thus CCHFV is classified as a hazard group 4 pathogen. In contrast HAZV is not associated with serious human disease, although infection of interferon receptor knockout mice with either CCHFV or HAZV results in similar disease progression. To characterise further similarities between HAZV and CCHFV, and support the use of HAZV as a model for CCHFV infection, we investigated the structure of the HAZV nucleocapsid protein (N) and compared it to CCHFV N. N performs an essential role in the viral life cycle by encapsidating the viral RNA genome, and thus, N represents a potential therapeutic target. Results: We present the purification, crystallisation and crystal structure of HAZV N at 2.7 Å resolution. HAZV N was expressed as an N-terminal glutathione S-transferase (GST) fusion protein then purified using glutathione affinity chromatography followed by ion-exchange chromatography. HAZV N crystallised in the P212121 space group with unit cell parameters a = 64.99, b = 76.10, and c = 449.28 Å. HAZV N consists of a globular domain formed mostly of alpha helices derived from both the N- and C-termini, and an arm domain comprising two long alpha helices. HAZV N has a similar overall structure to CCHFV N, with their globular domains superposing with an RMSD = 0.70 Å, over 368 alpha carbons that share 59 % sequence identity. Four HAZV N monomers crystallised in the asymmetric unit, and their head-to-tail assembly reveals a potential interaction site between monomers. Conclusions: The crystal structure of HAZV N reveals a close similarity to CCHFV N, supporting the use of HAZV as a model for CCHFV. Structural similarity between the N proteins should facilitate study of the CCHFV and HAZV replication cycles without the necessity of working under containment level 4 (CL-4) conditions

Mapping the medical outcomes study HIV health survey (MOS-HIV) to the EuroQoL 5 Dimension (EQ-5D-3L) utility index

10.1186/s12955-019-1135-8Health and Quality of Life Outcomes1718

Immunodiagnostic potential of a 27 kDa protein of Fusarium xylarioides, the cause of coffee wilt disease in Robusta coffee in Uganda

Several Fusarium species infect Robusta coffee; these Fusarium xylarioides Steyaert (Gibberella xylarioides Heim and Saccas) are the most virulent and responsible for the destructive Robusta coffee wilt disease in Uganda. To date, F. xylarioides has not been isolated directly from soil, though the pathogen can persist in soil for a short time. In this study, a promising diagnostic target which can be developed into a serological test for F. xylarioides in coffee plants and soil has been identified and validated for identification. Water-soluble extracts of mycelia from six Fusaruim species were resolved by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The different protein profiles from the other five Fusarium species were compared and contrasted with that of F. xylarioides. Protein bands that appeared peculiar to F. xylarioides were cut and injected into rabbits to produce polyclonal antibodies. Dot blot and Western blot analyses showed one immunodominant antigen (27 kDa) common to all F. xylarioides isolates analyzed. No cross-reactivity of anti-27 kDa antibodies were observed in the entire test Fusarium species. The results suggest that polyclonal antibodies raised against the endoantigens from F. xylarioides of 27 kDa, is a promising tool for the rapid, sensitive, and accurate detection of pathogen in soil and plant parts.Keywords: Gibberella xylarioides, coffee wilt disease, antigen, antibodies, Uganda.African Journal of Biotechnology, Vol 13(29) 2922-292

Seed transmission of Fusarium xylarioides in Coffea canephora in Uganda

No Abstract

The banana weevil, Cosmopolites sordidus (Germar), is a potential vector of Xanthomonas campestris pv. musacearum in bananas

This study was carried out to investigate the potential role of banana weevils as vectors of Xanthomonas campestris pv. musacearum (Xcm), causal agent of banana wilt. Weevils captured from Xcm-infected plants were tested for presence of Xcm, and further raised on Xcm-infected corms for later use as vectors to transmit the pathogen to healthy tissue-cultured plantlets. Analysis of weevils captured from diseased fields revealed more weevils contained Xcm originating from ‘Mbwazirume’ compared with ‘Kayinja’ cultivars. Colonies of Xcm were recovered from the weevil external body surface, internal organs (mouth parts and abdomen) and faecal matter. There was significantly higher Xcm presence and cfu mL−1 on the external weevil body surface than within the internal organs. Bacterial populations declined progressively from the external body surface, internal mouth parts, internal abdominal parts and the faecal matter. Following placement of weevils previously fed on Xcm-exuding corms in close proximity to healthy potted plants, infection occurred, with characteristic disease symptoms observed on all cultivars evaluated except ‘Kayinja’ which remained symptomless. Isolation from both symptomatic and asymptomatic plants revealed erratic Xcm incidence and cfu g−1 that did not correlate to the number of weevils released in all cultivars, except for ‘Kayinja’. This study showed that Xcm can survive on and within the banana weevil and potentially spread the pathogen to neighbouring plants. Résumé Cette étude a été menée dans le but d’évaluer le possible rôle que jouent les charançons du bananier en tant que vecteurs de Xanthomonas campestris pv. musacearum (Xcm), l’agent causal du flétrissement du bananier. Les charançons capturés sur des plants infectés par Xcm ont été testés pour l’y déceler, puis élevés sur des cormes infectés afin de les utiliser comme vecteurs dans le but de transmettre l’agent pathogène à des plantules saines issues de la culture tissulaire. L’analyse des charançons capturés dans des champs infectés a révélé qu’un plus grand nombre d’insectes contenaient le Xcm provenant du cultivar ‘Mbwazirume’ que du cultivar ‘Kayinja’. Des colonies de Xcm ont été récupérées de la surface du corps, des organes internes (pièces buccales et abdomen) et des fèces des charançons. La surface de la carapace des charançons affichait un taux significativement plus élevé de Xcm et de cfu ml−1 que leurs organes internes. Les populations bactériennes décroissaient graduellement en passant de la surface du corps aux pièces buccales internes, aux organes internes de l’abdomen puis aux fèces. Après avoir placé les charançons s’étant préalablement nourris de cormes exsudant le Xcm sur des plants en pot sains, l’infection est survenue, tous les cultivars évalués affichant les symptômes caractéristiques de la maladie, sauf ‘Kayinja’ qui est demeuré intouché. L’isolement des plants symptomatiques et asymptomatiques a révélé une incidence irrégulière de Xcm ainsi que des cfu g−1 qui n’étaient pas corrélés au nombre de charançons relâchés sur tous les cultivars, sauf pour ‘Kayinja’. Cette étude a montré que Xcm peut survivre sur et dans les charançons du bananier et transmettre l’agent pathogène aux plants croissant à proximité

Structural insights into RNA encapsidation and helical assembly of the Toscana virus nucleoprotein

Toscana virus is an emerging bunyavirus in Mediterranean Europe where it accounts for 80% of pediatric meningitis cases during the summer. The negative-strand ribonucleic acid (RNA) genome of the virus is wrapped around the virally encoded nucleoprotein N to form the ribonucleoprotein complex (RNP). We determined crystal structures of hexameric N alone (apo) and in complex with a nonameric single-stranded RNA. RNA is sequestered in a sequence-independent fashion in a deep groove inside the hexamer. At the junction between two adjacent copies of Ns, RNA binding induced an inter-subunit rotation, which opened the RNA-binding tunnel and created a new assembly interface at the outside of the hexamer. Based on these findings, we suggest a structural model for how binding of RNA to N promotes the formation of helical RNPs, which are a characteristic hallmark of many negative-strand RNA viruses

Potent anti tumor response by targeting B cell maturation antigen BCMA in a mouse model of multiple myeloma

Multiple myeloma (MM) is an aggressive incurable plasma cell malignancy with a median life expectancy of less than seven years. Antibody-based therapies have demonstrated substantial clinical benefit for patients with hematological malignancies, particular in B cell Non-Hodgkin's lymphoma. The lack of immunotherapies specifically targeting MM cells led us to develop a human-mouse chimeric antibody directed against the B cell maturation antigen (BCMA), which is almost exclusively expressed on plasma cells and multiple myeloma cells. The high affinity antibody blocks the binding of the native ligands APRIL and BAFF to BCMA. This finding is rationalized by the high resolution crystal structure of the Fab fragment in complex with the extracellular domain of BCMA. Most importantly, the antibody effectively depletes MM cells in vitro and in vivo and substantially prolongs tumor-free survival under therapeutic conditions in a xenograft mouse model. A BCMA-antibody-based therapy is therefore a promising option for the effective treatment of multiple myeloma and autoimmune diseases

Dietary flaxseed cake influences on performance, quality, and sensory attributes of eggs, serum, and egg trace minerals of laying hens

Nowadays, there is a global shortage in feed supply for animal nutrition; however, there are a considerable amount of agro-industrial co- and by-products that may offer a reasonable solution. Flaxseed cake (FSC) is a by-product of flaxseed for oil extraction rich in n-3 α-linolenic acid (ALA). Thus, the dietary inclusion of FSC on laying performance, egg quality, and serum and egg trace elements (Se, Zn, and Fe) was evaluated using Hisex White hens. The hens were distributed to three equal experimental treatments and provided diets including 0%, 5%, or 10% FSC from 48 to 58 weeks of age. Findings clarified that up to 10% FSC in the laying hen diet had no detrimental effect on laying rate, egg mass, and feed utilization. It was found that FSC resulted in a valuable source of protein, energy, macro- (Ca and P), micro- (Se, Zn and Fe) elements, and essential amino acids, with arginine being the highest. Dietary FSC did not negatively influence the egg quality traits, as well as egg sensory attributes. Including 5% or 10% FSC in diet did not significantly affect serum total protein and renal function in terms of creatinine, uric acid, and uric acid-to-creatinine ratio. Different FSC levels did not influence the chemical composition of eggs and trace elements in serum and eggs. It could be concluded that FSC is a valuable feedstuff that can provide a good source of energy, protein, amino acids, and macro- and micro-elements for hens’ nutrition. The inclusion of up to 10% of FSC in hens diet did not adversely influence egg laying performance, egg quality of both fresh and stored eggs, sensory attributes, and nutritional composition, as well as Se, Zn, and Fe in serum and eggs due to balanced nutrient profile of FSC