International agricultural research to reduce food risks: case studies on aflatoxins

Despite massive expansion of human and livestock populations, fuelled by agricultural innovations, nearly one billion people are hungry and 2 billion are sickened each year from the food they eat. Agricultural and food systems are intimately connected to health outcomes, but health policy and programs often stop at the clinic door. A consensus is growing that the disconnection between agriculture, health and nutrition is at least partly responsible for the disease burden associated with food and farming. Mycotoxins produced by fungi are one of the most serious food safety problems affecting staple crops (especially maize and groundnuts). Aflatoxins, the best studied of these mycotoxins, cause around 90,000 cases of liver cancer each year and are strongly associated with stunting and immune suppression in children. Mycotoxins also cause major economic disruptions through their impacts on trade and livestock production. In this paper we use the case of fungal toxins to explore how agricultural research can produce innovations, understand incentives and enable institutions to improve, simultaneously, food safety, food accessibility for poor consumers and access to markets for smallholder farmers, thus making the case for research investors to support research into agricultural approaches for enhancing food safety in value chains. We first discuss the evolution of food safety research within the CGIAR. Then we show how taking an epidemiological and economic perspective on aflatoxin research connects health and nutrition outcomes. Finally, we present three case studies illustrating the traditional strengths of CGIAR research: breeding better varieties and developing new technologies

Powdery mildew (Erysiphaceae) on Calibrachoa hybrids in Germany, Nicaragua and the USA

Abstract Cultivated Calibrachoa hybrids were previously thought to be resistant to powdery mildew, but infections have been recently encountered in Germany, USA and Nicaragua. The exclusive development of asexual morphs (anamorphs) led to the question as to which powdery mildew species might be involved as causal agents. Based on inoculation experiments and molecular sequence analyses, it was determined that powdery mildew infections on Calibrachoa in Europe (Germany), North America (USA), and Central America (Nicaragua) were found to be caused by the plurivorous Podosphaera xanthii. The anamorph is a typical Fibroidium characterized by conidia formed in chains (catenescent), containing distinct fibrosin bodies. Calibrachoa powdery mildew caused by P. xanthii could be easily transferred to cucumber, squash and Verbena ×hybrida and vice versa in the latter case. Attempts to inoculate petunias failed. In addition to P. xanthii, two additional powdery mildew species were found infecting Calibrachoa ×hybrida in Germany. The first, characterized by having lobed hyphal appressoria and conidia formed singly, can be assigned to Pseudoidium neolycopersici, and the second species, readily distinguishable by its very long conidiophores, conidia in chains with sinuate outline and nipple-shaped hyphal appressoria, belongs to Euoidium longipes. In the course of the current examinations, E. longipes was also found on Verbena ×hybrida, which represents the first record of this species on a non-solanaceous host

Mechanisms of Antiviral Activity of Iminosugars Against Dengue Virus

The antiviral mechanism of action of iminosugars against many enveloped viruses, including dengue virus (DENV), HIV, influenza and hepatitis C virus, is believed to be mediated by inducing misfolding of viral N-linked glycoproteins through inhibition of host endoplasmic reticulum-resident α-glucosidase enzymes. This leads to reduced secretion and/or infectivity of virions and hence lower viral titres, both in vitro and in vivo. Free oligosaccharide analysis from iminosugar-treated cells shows that antiviral activity correlates with production of mono- and tri-glucosylated sugars, indicative of inhibition of ER α-glucosidases. We demonstrate that glucose-mimicking iminosugars inhibit isolated glycoprotein and glycolipid processing enzymes and that this inhibition also occurs in primary cells treated with these drugs. Galactose-mimicking iminosugars that have been tested do not inhibit glycoprotein processing but do inhibit glycolipid processing, and are not antiviral against DENV. By comparison, the antiviral activity of glucose-mimetic iminosugars that inhibit endoplasmic reticulum-resident α-glucosidases, but not glycolipid processing, demonstrates that inhibition of α-glucosidases is responsible for iminosugar antiviral activity against DENV. This monograph will review the investigations of many researchers into the mechanisms of action of iminosugars and the contribution of our current understanding of these mechanisms for optimising clinical delivery of iminosugars. The effects of iminosugars on enzymes other than glucosidases, the induction of ER stress and viral receptors will be also put into context. Data suggest that inhibition of α-glucosidases results in inhibited release of virus and is the primary antiviral mechanism of action of iminosugars against DENV