Host Genetic Factors Affect Susceptibility to Norovirus Infections in Burkina Faso

Norovirus (NoV) constitutes the second most common viral pathogen causing pediatric diarrhea after rotavirus. In Africa, diarrhea is a major health problem in children, and yet few studies have been performed regarding NoV. The association of histo-blood group antigens (HBGA) and susceptibility to NoV infection is well established in Caucasian populations with non-secretors being resistant to many common NoV strains. No study regarding HBGA and NoV susceptibility has yet been performed in Africa. We collected 309 stool and 208 saliva samples from diarrheal children in Ouagadougou, Burkina Faso; May 2009 to March 2010. NoV was detected using real-time PCR, and genotyped by sequencing. Saliva samples were ABO, Lewis and secretor phenotyped using in house ELISA assays. NoV was detected in 12% (n = 37) of the samples. The genotype diversity was unusually large; overall the 37 positive samples belonged to 14 genotypes. Only children <2 years of age were NoV positive and the GII.4 NoVs were more frequent in the late dry season (Jan-May). NoV infections were observed less in children with the secretor-negative phenotype or blood group A (OR 0.18; p = 0.012 and OR 0.31; p = 0.054; respectively), with two non-secretors infected with genotypes GII.7 and GII.4 respectively. Lewis-negative (Le^a−b−) children, representing 32% of the study population, were susceptible to GII, but were not infected with any NoV GI. GII.4 strains preferentially infected children with blood group B whereas secretor-positive children with blood group O were infected with the largest variety of genotypes. This is the first study identifying host genetic factors associated with susceptibility to NoV in an African population, and suggests that while the non-secretor phenotype provides protection; the Lewis b antigen is not necessary for GII infection.     

Haemoglobin S and C affect the motion of Maurer's clefts in Plasmodium falciparum‐infected erythrocytes

The haemoglobinopathies S and C protect carriers from severe Plasmodium falciparum malaria. We have recently shown that haemoglobin S and C interfere with host‐actin remodelling in parasitized erythrocytes and the generation of an actin network that seems to be required for vesicular protein trafficking from the Maurer's clefts (a parasite‐derived intermediary protein secretory organelle) to the erythrocyte surface. Here we show that the actin network exerts skeletal functions by anchoring the Maurer's clefts within the erythrocyte cytoplasm. Using a customized tracking tool to investigate the motion of single Maurer's clefts, we found that a functional actin network restrains Brownian motion of this organelle. Maurer's clefts moved significantly faster in wild‐type erythrocytes treated with the actin depolymerizing agent cytochalasin D and in erythrocytes containing the haemoglobin variants S and C. Our data support the model of an impaired actin network being an underpinning cause of cellular malfunctioning in parasitized erythrocytes containing haemoglobin S or C, and, possibly, for the protective role of these haemoglobin variants against severe malaria.     

A Malian native plant growth promoting Actinomycetes based biofertilizer improves maize growth and yield

This study was carried out to evaluate the effect of Actinomycetes with Plant growoth promoting activity on the growth and yield of maize. This allowed the selection of three Actinomycetes: Actinomycetes sp. H7, O19 and AHB12 for their ability to solubilize phosphates, fix atmospheric nitrogen, and produce antimicrobial substances, enzymes, phytohormones and for their high vigour index. Five seeds, previously sanitized, inoculated and coated, were sown per pot. The best isolates selected in greenhouses were tested in station experiments. In pot, the inoculated seeds, with Actinomycete sp. H7 gave the best growth in plant size, 19.3% more compared to the uninoculated control (P?≤?0.05). In station experiments, it was found that Actinomycete sp. H7 significantly increased the fresh and dry biomass of the aerial part with 919.7 g and 405.6 g, respectively, against 636.70 g and 297.36 g respectively for the control. The best yield of seeds was obtained with the combination O19-AHB12 with a yield of 311.5 g for 1000 seeds compared to 178.28 g for the uninoculated control. All corn seeds inoculated showed better growth than controls. These results confirm the value of the PGPRs and above all open a way for the formulation and the use of biofertilizers based on PGPRs in Mali.