title: Phylogenetic analysis and genetic diversity of 3' region of rtxA gene from geographically diverse strains of Moraxella bovis, Moraxella bovoculi and Moraxella ovis.
abstract: The cytotoxin A (MbxA) is one of the main virulence factors of Moraxella bovis involved in the pathogenesis of infectious bovine keratoconjunctivitis (IBK). Moraxella ovis and Moraxella bovoculi, suspected to be associated with infectious keratitis in sheep and cattle respectively, also have a gene that encodes the cytotoxin A (movA and mbvA, respectively). The aim of this study was to determine the molecular sequence of the 3' region of the cytotoxin gene of Moraxella spp. strains isolated from clinical cases to establish phylogenetic and evolutionary comparisons. PCR amplification, nucleotide sequencing (nt) and amino acid (aa) sequence prediction were performed, followed by the sequences comparison, identity level calculation and selective pressure analysis. The phylogenetic reconstruction based on nt and aa sequences clearly differentiate M. bovis (n=15), M. bovoculi (n=11) and M. ovis (n=7) and their respective reference strains. An alignment of 843nt revealed high similarity within bacterial species (MbxA=99.9% nt and aa; MbvA=99.3% nt and 98.8% aa; MovA=99.5% nt and 99.3% aa). The similarity of partial sequences (nt 1807-2649) of MbxA in relation to MbvA and MovA ranged from 76.3 to 78.5%; similarity between MbvA and MovA ranged from 95.7 to 97.5%. A negative selection on mbvA and movA sequences was revealed by the molecular evolution analysis. The phylogenetic analysis of movA and mbvA allowed different strains of Moraxella spp. to be grouped according to the period of isolation. Sequence analysis of cytotoxin may provide insights into genetic and evolutionary relationships and into the genetic/molecular basis of Moraxella spp.
authors.affiliation: Setor de Bacteriologia, Departamento de Medicina Veterinária Preventiva, Universidade Federal de Santa Maria (UFSM), Av. Roraima, 1000, Camobi, Santa Maria, Rio Grande do Sul (RS) CEP 97105-900, Brazil. Electronic address: luana.vett@gmail.com.
authors.forename: Luana D'Avila
authors.initials: LD
authors.lastname: Farias
authors.affiliation: School of Veterinary Medicine and Science, University of Nottingham, Loughborough LE12 5RD, United Kingdom.
authors.forename: Grazieli
authors.initials: G
authors.lastname: Maboni
authors.affiliation: Departamento de Ciências da Saúde, Curso de Farmácia, Universidade Regional Integrada do Alto Uruguai e das Missões, Campus Santo Ângelo, RS CEP 98802-470, Brazil.
authors.forename: Letícia Beatriz
authors.initials: LB
authors.lastname: Matter
authors.affiliation: Médico Veterinário, Hipra Saúde Animal Ltda, Avenida do Lami 6133, Porto Alegre RS 91780-120, Brazil.
authors.forename: Charles Fernando Capinos
authors.initials: CF
authors.lastname: Scherer
authors.affiliation: Setor de Bacteriologia, Departamento de Medicina Veterinária Preventiva, Universidade Federal de Santa Maria (UFSM), Av. Roraima, 1000, Camobi, Santa Maria, Rio Grande do Sul (RS) CEP 97105-900, Brazil.
authors.forename: Felipe
authors.initials: F
authors.lastname: Libardoni
authors.affiliation: Setor de Bacteriologia, Departamento de Medicina Veterinária Preventiva, Universidade Federal de Santa Maria (UFSM), Av. Roraima, 1000, Camobi, Santa Maria, Rio Grande do Sul (RS) CEP 97105-900, Brazil. Electronic address: agueda.vargas@gmail.com.
authors.forename: Agueda Castagna
authors.initials: AC
authors.lastname: de Vargas
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology*; D003603:Cytotoxins / Q000235:genetics; D014644:Genetic Variation; D005843:Geography; D007639:Keratoconjunctivitis, Infectious / Q000382:microbiology*; D008969:Molecular Sequence Data; D009016:Moraxella / Q000235:genetics* / Q000302:isolation & purification; D016955:Moraxella bovis / Q000235:genetics / Q000302:isolation & purification; D045828:Moraxellaceae Infections / Q000382:microbiology / Q000662:veterinary*; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D012756:Sheep; D012757:Sheep Diseases / Q000382:microbiology*
chemical_list: D003603:Cytotoxins
keywords: Cytolysin; Hemolysin; Infectious bovine keratoconjunctivitis; RTX operon