Diversity in gene arrangement in a DNA region lacking aerA in clinical and environmental Aeromonas hydrophila isolates
- 63 Downloads
Aquatic pathogen Aeromonas hydrophila produces an array of virulence factors, many of which are excreted proteins that causes infectious disease in fish, reptiles, and humans. Aerolysin, a haemolytic toxin, is the most well-known of the A. hydrophila virulence factors and is encoded by aerA. Although used as a virulence gene marker in several studies, recent whole-genome sequencing data suggest there may be some variation in aerolysin genes, as well as in the genetic environment of these genes, among A. hydrophila strains. Here, we used PCR-based assays to examine gene arrangement in the traditional aerA region of 42 aerA-minus clinical and environmental A. hydrophila isolates. PCR primers were designed based on known genes from within the target regions of reference strains carrying non-aerA aerolysin genes. Analyses revealed four different gene arrangement patterns among the isolates, indicating considerable genetic diversity in the target region. While 19 of the 21 environmental isolates showed the same gene pattern, all four patterns were represented among the clinical isolates, implying that the gene pattern is highly conserved in the target region among environmental isolates. Further analysis of the gene regions showed that the predominant pattern among environmental isolates, which did not contain an aerolysin gene, appeared to be the progenitor of the other three patterns, which likely arose as a result of gene acquisition, deletion, and rearrangement events during the evolution of A. hydrophila, and may be linked to the acquisition of aerolysin genes. These findings shed light on the evolution of virulence in A. hydrophila.
KeywordsAerolysin gene Aeromonas hydrophila Clinical isolates Environmental isolates Genetic diversity
We thank Tamsin Sheen, PhD, from Edanz Group (www.edanzediting.com/ac) for editing a draft of this manuscript and helping to draft the abstract.
NW designed the study, performed the research, analysed the data and wrote the paper. KM analysed the data.
This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Aguilera-Arreola MG, Hernández-Rodríguez C, Zúñiga G, Figueras MJ, Castro-Escarpulli G (2005) Aeromonas hydrophila clinical and environmental ecotypes as revealed by genetic diversity and virulence genes. FEMS Microbiol Lett 242:231–240. https://doi.org/10.1016/j.femsle.2004.11.011 CrossRefPubMedGoogle Scholar
- Aguilera-Arreola MG, Hernández-Rodríguez C, Zúñiga G, Figueras MJ, Garduño RA, Castro-Escarpulli G (2007) Virulence potential and genetic diversity of Aeromonas caviae, Aeromonas veronii, and Aeromonas hydrophila clinical isolates from Mexico and Spain: a comparative study. Can J Microbiol 53:877–887. https://doi.org/10.1007/s10096-014-2157-0 CrossRefPubMedGoogle Scholar
- Aravena-Román M, Inglis TJJ, Riley TV, Chang BJ (2014) Distribution of 13 virulence genes among clinical and environmental Aeromonas spp. in Western Australia. Eur J Clin Microbiol Infect Dis Off Publ Eur Soc Clin Microbiol 33:1889–1895. https://doi.org/10.1007/s10096-014-2157-0 CrossRefGoogle Scholar
- Fukuyama M, Kamimura T, Itoh T, Murata M, Kohzaki K, Hara M, Tabuchi K (1989) Studies on motile-Aeromonas infection: incidence of motile-Aeromonas in river mud, river water and fresh-water fish. Kansenshogaku Zasshi 63:565–574. https://doi.org/10.11150/kansenshogakuzasshi1970.63.565 CrossRefPubMedGoogle Scholar
- Ghatak S, Blom J, Das S, Sanjukta R, Puro K, Mawlong M, Shakuntala I, Sen A, Goesmann A, Kumar A, Ngachan SV (2016) Pan-genome analysis of Aeromonas hydrophila, Aeromonas veronii and Aeromonas caviae indicates phylogenomic diversity and greater pathogenic potential for Aeromonas hydrophila. Antonie Van Leeuwenhoek 109:945–956. https://doi.org/10.1007/s10482-016-0693-6 CrossRefPubMedGoogle Scholar
- Janda JM, Abbott SL (1996) Human pathogens. In: Austin B, Altwegg M, Gosling PJ, Joseph S (eds) The genus Aeromonas. Wiley, Chichester, pp 151–173Google Scholar
- Mateos D, Anguita J, Naharro G, Paniagua C (1993) Influence of growth temperature on the production of extracellular virulence factors and pathogenicity of environmental and human strains of Aeromonas hydrophila. J Appl Bacteriol 74:111–118. https://doi.org/10.1111/j.1365-2672.1993.tb03003.x CrossRefPubMedGoogle Scholar
- Seshadri R, Joseph SW, Chopra AK, Sha J, Shaw J, Graf J, Haft D, Wu M, Ren Q, Rosovitz MJ, Madupu R, Tallon L, Kim M, Jin S, Vuong H, Stine OC, Ali A, Horneman AJ, Heidelberg JF (2006) Genome sequence of Aeromonas hydrophila ATCC 7966T: jack of all trades. J Bacteriol 188:8272–8282. https://doi.org/10.1128/JB.00621-06 CrossRefPubMedPubMedCentralGoogle Scholar
- Soltan Dallal MM, Mazaheri Nezhad Fard R, Kavan Talkhabi M, Aghaiyan L, Salehipour Z (2016) Prevalence, virulence and antimicrobial resistance patterns of Aeromonas spp. isolated from children with diarrhea. Germs 6:91–96. https://doi.org/10.11599/germs.2016.1094 CrossRefPubMedPubMedCentralGoogle Scholar
- Talagrand-Reboul E, Latif-Eugenín, Beaz-Hidalgo R, Colston S, Figueras MJ, Graf J, Jumas-Bilak E, Lamy B (2018) Genome-driven evaluation and redesign of PCR tools for improving the detection of virulence-associated genes in aeromonads. PLoS ONE 13(8): e0201428. https://doi.org/10.1371/2Fjournal.pone.0201428 CrossRefPubMedPubMedCentralGoogle Scholar
- Wamala SP, Mugimba KK, Dubey S, Takele A, Munang'andu HM, Evensen Ø, Mutoloki S, Byarugaba DK, Sørum H (2018) Multilocus sequence analysis revealed a high genotypic diversity of Aeromonas hydrophila infecting fish in Uganda. J Fish Dis 41:1589–1600. https://doi.org/10.1111/jfd.12873 CrossRefPubMedGoogle Scholar
- Watanabe N, Morita K, Furukawa T, Manzoku T, Endo E, Kanamori M (2004) Sequence analysis of amplified DNA fragments containing the region encoding the putative lipase substrate-binding domain and genotyping of Aeromonas hydrophila. Appl Environ Microbiol 70:145–151CrossRefPubMedPubMedCentralGoogle Scholar
- Zhou Y, Fan Y, Jiang N, Liu W, Shi Y, Zhao J, Zeng L (2018) Molecular characteristics and virulence analysis of eight Aeromonas hydrophila isolates obtained from diseased Amur sturgeon Acipenser schrenckii Brandt, 1869. J Vet Med Sci 80:421–426. https://doi.org/10.1038/s41598-018-36376-2 CrossRefPubMedPubMedCentralGoogle Scholar