BioSample

Honey bees infected with N. ceranae were collected from the USDA-ARS Bee Research Laboratory apiaries, Beltsville, MD. Alimentary tracts of these bees were removed and crushed in sterile water and filtered through a Corning (Lowell, MA) Netwell insert (24 mm diameter, 74 μm mesh size) to remove tissue debris. The filtered suspension was centrifuged at 3,000 x g for 5 minutes and the supernatant discarded. The re-suspended pellet was further purified on a discontinuous Percoll (Sigma-Aldrich, St. Louis, MO) gradient consisting of 5 ml each of 25%, 50%, 75% and 100% Percoll solution. The spore suspension was overlaid onto the gradient and centrifuged at 8,000 x g for 10 minutes at 4o C. The supernatant was discarded and the spore pellet was washed by centrifugation and suspension in distilled sterile water.