Testing intra-hemocelic injection of antimicrobials against Encephalitozoon sp. (Microsporidia) in an insect host

Identification and subcellular localization analysis of membrane protein Ycf 1 in the microsporidian Nosema bombycis

Microsporidia are obligate intracellular parasites that can infect a wide range of vertebrates and invertebrates including humans and insects, such as silkworm and bees. The microsporidium Nosema bombycis can cause pebrine in Bombyx mori, which is the most destructive disease in the sericulture industry. Although membrane proteins are involved in a wide range of cellular functions and part of many important metabolic pathways, there are rare reports about the membrane proteins of microsporidia up to now. We screened a putative membrane protein Ycf 1 from the midgut transcriptome of the N. bombycis-infected silkworm. Gene cloning and bioinformatics analysis showed that the Ycf 1 gene contains a complete open reading frame (ORF) of 969 bp in length encoding a 322 amino acid polypeptide that has one signal peptide and one transmembrane domain. Indirect immunofluorescence results showed that Ycf 1 protein is distributed on the plasma membrane. Expression pattern analysis showed that the Ycf 1 gene expressed in all developmental stages of N. bombycis. Knockdown of the Ycf 1 gene by RNAi effectively inhibited the proliferation of N. bombycis. These results indicated that Ycf 1 is a membrane protein and plays an important role in the life cycle of N. bombycis.

Mechanism of carbendazim in treating pebrine disease of Bombyx mori based on GC/MS-based metabonomics

Pebrine disease is caused by microporidia (Nosema bombycis) and is destructive to sericulture production. A carbendazim-based drug FangWeiLing (FWL) has a significant control effect on the disease, which is a successful example of drug treatment of microsporidia. In this study, the therapeutic effect and critical action time of FWL were investigated by silkworm rearing biological test. Besides, the hemolymph samples from silkworms in the control group, model group, and FWL group were analyzed by metabonomics based on gas chromatography-mass spectrometry (GC/MS). The results showed that FWL had a significant therapeutic effect on pebrine disease, and the critical action time was 24 ~ 48 h post inoculation. Forty-seven different metabolites related to pebrine disease were screened out, and correlated with starch and sucrose metabolism; aminoacyl-tRNA biosynthesis; arginine biosynthesis; glycine, serine, and threonine metabolism; and phenylalanine, tyrosine, and tryptophan biosynthesis. After pretreatment with FWL, the metabolites were all effectively regulated, indicating productive intervention. Principal component analysis (PCA) also showed that the overall metabolic profile of the FWL group tended toward the control group. Compared with the control group, 16 different metabolites were obtained from the hemolymph of B.mori in FWL group, mainly involving aminoacyl-tRNA biosynthesis and taurine and hypotaurine metabolism. It indicated that FWL had some effect on silkworm metabolism, which might be related to the decrease in cocoon quality. In conclusion, combined with the life cycle of N. bombycis, the mechanism of carbendazim in the treatment of pebrine disease can be fully revealed. Carbendazim can effectively reduce the destruction of amino acid metabolism and carbohydrate metabolism by N. Bombycis infection by inhibiting the proliferation of the meronts in silkworms, thus maintaining the normal physiological state of B. mori and achieve therapeutic effects. GC/MS-based metabonomics is a valuable and promising strategy to understand the disease mechanism and drug treatment of pebrine disease.

Identification of candidate agents active against N. ceranae infection in honey bees: establishment of a medium throughput screening assay based on N. ceranae infected cultured cells

Many flowering plants in both natural ecosytems and agriculture are dependent on insect pollination for fruit set and seed production. Managed honey bees (Apis mellifera) and wild bees are key pollinators providing this indispensable eco- and agrosystem service. Like all other organisms, bees are attacked by numerous pathogens and parasites. Nosema apis is a honey bee pathogenic microsporidium which is widely distributed in honey bee populations without causing much harm. Its congener Nosema ceranae was originally described as pathogen of the Eastern honey bee (Apis cerana) but jumped host from A. cerana to A. mellifera about 20 years ago and spilled over from A. mellifera to Bombus spp. quite recently. N. ceranae is now considered a deadly emerging parasite of both Western honey bees and bumblebees. Hence, novel and sustainable treatment strategies against N. ceranae are urgently needed to protect honey and wild bees. We here present the development of an in vitro medium throughput screening assay for the identification of candidate agents active against N. ceranae infections. This novel assay is based on our recently developed cell culture model for N. ceranae and coupled with an RT-PCR-ELISA protocol for quantification of N. ceranae in infected cells. The assay has been adapted to the 96-well microplate format to allow automated analysis. Several substances with known (fumagillin) or presumed (surfactin) or no (paromomycin) activity against N. ceranae were tested as well as substances for which no data concerning N. ceranae inhibition existed. While fumagillin and two nitroimidazoles (metronidazole, tinidazole) totally inhibited N. ceranae proliferation, all other test substances were inactive. In summary, the assay proved suitable for substance screening and demonstrated the activity of two synthetic antibiotics against N. ceranae.

Bacterial and parasitic diseases of selected invertebrates

Invertebrate medicine is a rapidly advancing aspect of veterinary medicine, although frustrating in its lack of answers and its limitations compared with vertebrate medicine. Because invertebrates make up 98% of animal life, it should be impossible to contain information on their known bacterial and parasitic diseases within a single article. When the focus is placed on those species commonly kept and treated by non-marine veterinarians, the amount of information becomes manageable. Many exotic species had their known diseases and treatments start this way and then advanced to a higher level of understanding. This article stands as an introduction to the parasitic and bacterial diseases of these fascinating creatures for the veterinary practitioner.