Field trials of anti-nosema drugs are expensive, time consuming and often inconclusive. The authors have developed a technique where they culture nosema infections in the lab and test various substances _in vitro_. They confirmed the effectiveness of fumagillin and the toxicity of various substances known to be toxic to cells. Then they tried other substances to evaluate their ability to control nosema and/or their toxicity to the host cells. Several potential substances were found to be ineffective, such as albendazole, which is used to control nosema in silkworms (N. bombycis). Two antibiotics were identified as potential control agents, but as they state, they would be prohibited for use on honey bees in many countries. 

> 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 cul- ture 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.

> These results indicated that at a concentration of 2 mg/ml both tinidazole and metronidazole can completely inhibit N. ceranae infection of IPL-LD 65Y cells and, therefore, were as effective as fumagillin in vitro. However, both substances will hardly have a future as anti-nosemosis drugs in honey bees. Nitroimidazoles are antibiotics and the use of antibiotics in honey bee colonies and in particular the use of nitroimidazoles in food animals and animal food is prohibited in many countries including the European Union.

Gisder, S., & Genersch, E. (2015). 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. PLoS ONE, 10(2), e0117200.

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html