title: The bacteriophage WORiC is the active phage element in wRi of Drosophila simulans and represents a conserved class of WO phages.
abstract: BACKGROUND
  The alphaproteobacterium Wolbachia pipientis, the most common endosymbiont in eukaryotes, is found predominantly in insects including many Drosophila species. Although Wolbachia is primarily vertically transmitted, analysis of its genome provides evidence for frequent horizontal transfer, extensive recombination and numerous mobile genetic elements. The genome sequence of Wolbachia in Drosophila simulans Riverside (wRi) is available along with the integrated bacteriophages, enabling a detailed examination of phage genes and the role of these genes in the biology of Wolbachia and its host organisms. Wolbachia is widely known for its ability to modify the reproductive patterns of insects. One particular modification, cytoplasmic incompatibility, has previously been shown to be dependent on Wolbachia density and inversely related to the titer of lytic phage. The wRi genome has four phage regions, two WORiBs, one WORiA and one WORiC.
  
  
  RESULTS
  In this study specific primers were designed to distinguish between these four prophage types in wRi, and quantitative PCR was used to measure the titer of bacteriophages in testes, ovaries, embryos and adult flies. In all tissues tested, WORiA and WORiB were not found to be present in excess of their integrated prophages; WORiC, however, was found to be present extrachromosomally. WORiC is undergoing extrachromosomal replication in wRi. The density of phage particles was found to be consistent in individual larvae in a laboratory population. The WORiC genome is organized in conserved blocks of genes and aligns most closely with other known lytic WO phages, WOVitA and WOCauB.
  
  
  CONCLUSIONS
  The results presented here suggest that WORiC is the lytic form of WO in D. simulans, is undergoing extrachromosomal replication in wRi, and belongs to a conserved family of phages in Wolbachia.
authors.affiliation: Department of Biological Sciences University of Alberta CW 403 Biological Sciences Building Edmonton, Alberta T6G 2E9, Canada.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Biliske
authors.forename: Philip D
authors.initials: PD
authors.lastname: Batista
authors.forename: Chantalle L
authors.initials: CL
authors.lastname: Grant
authors.forename: Harriet L
authors.initials: HL
authors.lastname: Harris
mesh_terms: D000818:Animals; D001435:Bacteriophages / Q000235:genetics* / Q000502:physiology; D004279:DNA, Viral / Q000235:genetics; D004330:Drosophila / Q000382:microbiology*; D005260:Female; D016679:Genome, Viral; D007814:Larva / Q000382:microbiology; D008297:Male; D010802:Phylogeny; D039002:Prophages / Q000235:genetics* / Q000502:physiology; D017422:Sequence Analysis, DNA; D014779:Virus Replication; D020577:Wolbachia / Q000821:virology*
chemical_list: D004279:DNA, Viral
references.citation: Biochem Biophys Res Commun. 2004 May 14;317(4):1183-8
references.pmid: 15094394
references.citation: Appl Environ Microbiol. 2009 Sep;75(17):5676-86
references.pmid: 19592535
references.citation: PLoS One. 2011 May 06;6(5):e19708
references.pmid: 21573076
references.citation: Insect Biochem Mol Biol. 2006 Jan;36(1):80-5
references.pmid: 16360953
references.citation: Biochem Biophys Res Commun. 2001 May 25;283(5):1099-104
references.pmid: 11355885
references.citation: J Bacteriol. 2009 Mar;191(5):1725
references.pmid: 19114486
references.citation: Bioinformatics. 2005 May 1;21(9):2104-5
references.pmid: 15647292
references.citation: BMC Biol. 2007 Sep 20;5:39
references.pmid: 17883830
references.citation: Mol Biol Evol. 2002 Mar;19(3):341-6
references.pmid: 11861893
references.citation: J Bacteriol. 2010 Nov;192(22):6064-76
references.pmid: 20870769
references.citation: Proc Natl Acad Sci U S A. 2009 Apr 7;106(14):5725-30
references.pmid: 19307581
references.citation: Mol Microbiol. 2003 Jul;49(2):277-300
references.pmid: 12886937
references.citation: Mol Biol Evol. 2008 Sep;25(9):1877-87
references.pmid: 18550617
references.citation: J Bacteriol. 2007 Jun;189(12):4442-8
references.pmid: 17449622
references.citation: Virol J. 2010 Dec 03;7:355
references.pmid: 21129200
references.citation: Microbiol Mol Biol Rev. 2003 Jun;67(2):238-76, table of contents
references.pmid: 12794192
references.citation: PLoS Biol. 2004 Mar;2(3):E69
references.pmid: 15024419
references.citation: Annu Rev Microbiol. 1999;53:71-102
references.pmid: 10547686
references.citation: Genetics. 2003 Jun;164(2):545-52
references.pmid: 12807775
references.citation: J Biosci. 2007 Aug;32(5):979-90
references.pmid: 17914239
references.citation: Insect Mol Biol. 2004 Apr;13(2):147-53
references.pmid: 15056362
references.citation: Syst Biol. 2003 Oct;52(5):696-704
references.pmid: 14530136
references.citation: Trends Microbiol. 2010 Apr;18(4):173-81
references.pmid: 20083406
references.citation: Mol Biol Evol. 2004 Oct;21(10):1981-91
references.pmid: 15254259
references.citation: J Bacteriol. 2000 Nov;182(22):6529-31
references.pmid: 11053403
references.citation: Proc Biol Sci. 1998 Mar 22;265(1395):509-15
references.pmid: 9569669
references.citation: PLoS Pathog. 2006 May;2(5):e43
references.pmid: 16710453
references.citation: Microbiology (Reading). 2009 Jul;155(Pt 7):2211-2222
references.pmid: 19389774
references.citation: Genome Biol Evol. 2011;3:209-18
references.pmid: 21292630
references.citation: Evolution. 1986 Jul;40(4):692-701
references.pmid: 28556160
references.citation: Annu Rev Genet. 2008;42:647-81
references.pmid: 18687036
references.citation: Insect Mol Biol. 2011 Feb;20(1):75-85
references.pmid: 20854481
references.citation: J Bacteriol. 2005 Aug;187(15):5136-45
references.pmid: 16030207
references.citation: Nucleic Acids Res. 2008 Jan;36(Database issue):D25-30
references.pmid: 18073190
references.citation: Proc Biol Sci. 1995 Jul 22;261(1360):55-63
references.pmid: 7644549
references.citation: Annu Rev Microbiol. 1989;43:267-92
references.pmid: 2679356
references.citation: J Bacteriol. 2002 Sep;184(17):4891-905
references.pmid: 12169615