02144nas a2200193   4500000000100000000000100001008004100002260007000043653002500113653001900138100002400157700001400181700001600195700001500211245021800226490000800444520148400452022001401936       2018                            d  c11/2018bSchlütersche Verlagsgesellschaft mbH & Co. KGaHannover10aintestinal infection10ahistopathology1 aH Aupperle-Lellbach1 aL Müller1 aA Fünfhaus1 aE Genersch00aEuropean Foulbrood in honey bees (Apis mellifera): Histological insights into the pathogenesis of larval infections with the low virulent Melissococcus plutonius strain LMG20360T belonging to the clonal complex 130 v1313 aEuropean Foulbrood (EFB) is a bacterial infection of honey bee larvae caused by Melissococcus  (M.) plutonius. Although this sometimes devastating brood disease has long been known,  pathogenesis and pathology of honey bee larval infections with M. plutonius still remain  largely elusive. We here present a histological investigation of the pathogenesis of intestinal  infection of honey bee larvae with M. plutonius LMG20360, a representative of the least  virulent clonal complex CC13. Three days post infection, ingested bacteria were detected  within the midgut. From day five post infection, the ingesta was nearly completely infiltrated  by bacteria but the peritrophic matrix and intestinal epithelium seemed to be and remained  intact until day 15 post infection. Evaluation of the larval development revealed that larval  growth was not significantly different in infected larvae compared to non-infected control  animals until day five post infection. However, from day seven post infection, the infected  larvae were significantly smaller than the non-infected control larvae. Based on our results  we concluded that the larvae infected with the low virulent strain of M. plutonius probably  only suffered from a lack of nutrients resulting in reduced growth once the bacteria started  to massively proliferate. However, the bacteria did not attack or destroy the intestinal wall  confirming the original view on the non-invasive character of M. plutonius infections.  a0005-9366