title: Morphological and molecular studies of Vairimorpha necatrix BM, a new strain of the microsporidium V. necatrix (Microsporidia, Burenellidae) recorded in the silkworm, Bombyx mori.
abstract: Vairimorpha sp. BM (2012) is a recent isolate of the microsporidia from the silkworm in Shandong, China. The ultrastructure, tissue pathology and molecular characterization of this isolate is described in this study. This pathogenic fungus causes pebrine disease in silkworms which manifests as a systemic infection. Meanwhile, the silkworm eggs produced by the infected moths were examined using a microscope and PCR amplification. Neither spores nor the expected PCR band were observed, suggesting that no vertical transmission occurred in Bombyx mori. In addition, the ultrastructure of the isolate was studied by light microscopy and transmission electron microscopy. Two types of spores were observed: diplokaroytic spores with 13-17 coils of polar tubes and monokaryotic spores with less coils of polar tubes which could form octospores; however, no sporophorous vesicles were observed. Finally, phylogenetic analysis of the small subunit rRNA genes of Vairimorpha species showed that this isolate has a closer relationship to Vairimorpha necatrix than the other species studied. This result also is supported by phylogenetic analysis based on their actin genes, heat shock protein 70 (HSP70) and RNA polymerase II (RPB1). Based on the information gained during this study, we propose that this microsporidian species infecting B. mori should be given the name V. necatrix BM.
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, PR China.
authors.forename: Bo
authors.initials: B
authors.lastname: Luo
authors.affiliation: Experimental Teaching Center, Chongqing Medical University, Chongqing 400016, PR China.
authors.forename: Handeng
authors.initials: H
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, PR China. Electronic address: gqpan@swu.edu.cn.
authors.forename: Guoqing
authors.initials: G
authors.lastname: Pan
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, PR China.
authors.forename: Tian
authors.initials: T
authors.lastname: Li
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, PR China.
authors.forename: Zeng
authors.initials: Z
authors.lastname: Li
authors.affiliation: Laboratory of Animal Biology, Chongqing Normal University, Chongqing 400047, PR China.
authors.forename: Xiaoqun
authors.initials: X
authors.lastname: Dang
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, PR China.
authors.forename: Tie
authors.initials: T
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, PR China; Laboratory of Animal Biology, Chongqing Normal University, Chongqing 400047, PR China.
authors.forename: Zeyang
authors.initials: Z
authors.lastname: Zhou
mesh_terms: D000818:Animals; D012831:Bombyx / Q000382:microbiology*; D007814:Larva / Q000382:microbiology; D046529:Microscopy, Electron, Transmission; D010063:Ovum / Q000382:microbiology; D050175:Pansporablastina / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000648:ultrastructure; D010802:Phylogeny; D012335:RNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D013172:Spores, Fungal / Q000302:isolation & purification / Q000648:ultrastructure
chemical_list: D012335:RNA, Ribosomal
keywords: Microsporidia; Silkworm; Ultrastructure; V. necatrix; Vertical transmission