Silencing of essential genes by RNA interference in Haemonchus contortus.

In this study we assessed three technologies for silencing gene expression by RNA interference (RNAi) in the sheep parasitic nematode Haemonchus contortus. We chose as targets five genes that are essential in Caenorhabditis elegans (mitr-1, pat-12, vha-19, glf-1 and noah-1), orthologues of which are present and expressed in H. contortus, plus four genes previously tested by RNAi in H. contortus (ubiquitin, tubulin, paramyosin, tropomyosin). To introduce double-stranded RNA (dsRNA) into the nematodes we tested (1) feeding free-living stages of H. contortus with Escherichia coli that express dsRNA targetting the test genes; (2) electroporation of dsRNA into H. contortus eggs or larvae; and (3) soaking adult H. contortus in dsRNA. For each gene tested we observed reduced levels of mRNA in the treated nematodes, except for some electroporation conditions. We did not observe any phenotypic changes in the worms in the electroporation or dsRNA soaking experiments. The feeding method, however, elicited observable changes in the development and viability of larvae for five of the eight genes tested, including the 'essential' genes, Hc-pat-12, Hc-vha-19 and Hc-glf-1. We recommend the E. coli feeding method for RNAi in H. contortus and provide recommendations for future research directions for RNAi in this species.

Development of a locally sustainable functional food for people living with HIV in Sub-Saharan Africa: laboratory testing and sensory evaluation.

The use of Lactobacillus rhamnosus GR-1 and micronutrients has been associated with a preserved immune function among people living with HIV. However, use of these products in the developing world remains limited due to the lack of facilities for production. We describe the development of a yogurt with L. rhamnosus GR-1 at >7×10(7) colony forming units fortified with locally grown Moringa oleifera leaves at 20% of the recommended daily allowance of vitamin A. The product was made by preparing a thin paste of Moringa which was then incubated with 4% probiotic and 2% yogurt mother culture in milk for 6 hours. The addition of M. oleifera enhanced the survival of probiotic bacteria in yogurt during the shelf life period at 5 °C (P=0.02), but had no effect on probiotic survival at 21 °C. While the sensory characteristics of probiotic and non-probiotic supplemented Moringa yogurts were indistinguishable, the addition of Moringa reduced consumer acceptance compared to regular yogurt.