Infection of Melissococcus plutonius clonal complex 12strain in European honeybee larvae is essentially confined to the digestivetract

Journal of Veterinary Medical Science

Masumi SATO²  Mikio YOSHIYAMA¹  Daisuke TAKAMATSU³ 

[1] Honey Bee Research Unit, Animal Breeding and Reproduction Research Division, NARO Institute of Livestock and Grassland Science, National Agriculture and Food Research Organization, 2 Ikenodai, Tsukuba, Ibaraki 305�?0901, Japan;Pathology and Pathophysiology Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, 3�?1�?5 Kannondai, Tsukuba, Ibaraki 305�?0856, Japan;Bacterial and Parasitic Diseases Research Division, National Institute of Animal Health, National Agriculture and Food Research Organization, 3�?1�?5 Kannondai, Tsukuba, Ibaraki 305�?0856, Japan

关键词: clonal complex 12 strain;    European foulbrood;    honeybee larvae;    intestinal infection;    Melissococcus plutonius;   

DOI  :  10.1292/jvms.15-0405

学科分类：兽医学

来源: Japanese Society of Veterinary Science

【 摘 要 】

References(13)Cited-By(1)Supplementary materials(1)Melissococcus plutonius is an important pathogen that causesEuropean foulbrood (EFB) in honeybee larvae. Recently, we discovered a group of M.plutonius strains that are phenotypically and genetically distinct from otherstrains. These strains belong to clonal complex (CC) 12, as determined by multilocussequence typing analysis, and show atypical cultural and biochemical characteristicsin vitro compared with strains of other CCs tested. Although EFB isconsidered to be a purely intestinal infection according to early studies, it is unknownwhether the recently found CC12 strains cause EFB by the same pathomechanism. In thisstudy, to obtain a better understanding of EFB, we infected European honeybee(Apis mellifera) larvae per os with awell-characterized CC12 strain, DAT561, and analyzed the larvae histopathologically.Ingested DAT561 was mainly localized in the midgut lumen surrounded by the peritrophicmatrix (PM) in the larvae. In badly affected larvae, the PM and midgut epithelial cellsdegenerated, and some bacterial cells were detected outside of the midgut. However, theydid not proliferate in the deep tissues actively. By immunohistochemical analysis, the PMwas stained with anti-M. plutonius serum in most of the DAT561-infectedlarvae. In some larvae, luminal surfaces of the PM were more strongly stained than theinside. These results suggest that infection of CC12 strain in honeybee larvae isessentially confined to the intestine. Moreover, our results imply the presence ofM. plutonius-derived substances diffusing into the larval tissues inthe course of infection.

【 授权许可】

Unknown