Search

During a study to assess the faecal microbiome of common seals (Phoca vitulina) in a Dutch seal rehabilitation centre, 16S rRNA gene sequences of an unknown Campylobacter taxon were identified. Campylobacter isolates, which differed from the established Campylobacter taxa, were cultured and their taxonomic position was determined by a polyphasic study based on ten isolates. The isolates were characterized by 16S rRNA and atpA gene sequence analyses and by conventional phenotypic testing. Based on the whole genome sequences, the average nucleotide identity and core genome phylogeny were determined. The isolates formed a separate phylogenetic clade, divergent from all other Campylobacter taxa and most closely related to Campylobacter corcagiensis, Campylobacter geochelonis and Campylobacter ureolyticus. The isolates can be distinguished phenotypically from all other Campylobacter taxa based on their lack of motility, growth at 25 °C and growth on MacConkey agar. This study shows that these isolates represent a novel species within the genus Campylobacter, for which the name Campylobacter blaseri sp. nov. is proposed. The type strain for this novel species is 17S00004-5 T (=LMG 30333 T =CCUG 71276 T ).

During independent diagnostic screenings of otariid seals in California (USA) and phocid seals in Scotland (UK), Campylobacter-like isolates, which differed from the established taxa of the genus Campylobacter, were cultured from abscesses and internal organs of different seal species. A polyphasic study was undertaken to determine the taxonomic position of these six isolates. The isolates were characterized by 16S rRNA gene and AtpA sequence analysis and by conventional phenotypic testing. The whole-genome sequences were determined for all isolates, and the average nucleotide identity (ANI) was determined. The isolates formed a separate phylogenetic clade, divergent from all other taxa of the genus Campylobacter and most closely related to Campylobactermucosalis. Although all isolates showed 100 % 16S rRNA gene sequence homology, AtpA and ANI analyses indicated divergence between the otariid isolates from California and the phocid isolates from Scotland, which warrants subspecies status for each clade. The two subspecies could also be distinguished phenotypically on the basis of catalase activity. This study shows clearly that the isolates obtained from pinnipeds represent a novel species within the genus Campylobacter, for which the name Campylobacter pinnipediorum sp. nov. is proposed. Within this novel species, the Californian isolates represent a separate subspecies, for which the name C. pinnipediorum subsp. pinnipediorum subsp. nov. is proposed. The type strain for both this novel species and subspecies is RM17260T (=LMG 29472T=CCUG 69570T). The Scottish isolates represent another subspecies, for which the name C. pinnipediorum subsp. caledonicus subsp. nov. is proposed. The type strain of this subspecies is M302/10/6T (=LMG 29473T=CCUG 68650T).

During sampling of reptiles for members of the class Epsilonproteobacteria, strains representing a member of the genus Campylobacter not belonging to any of the established taxa were isolated from lizards and chelonians. Initial amplified fragment length polymorphism, PCR and 16S rRNA sequence analysis showed that these strains were most closely related to Campylobacter fetus and Campylobacter hyointestinalis. A polyphasic study was undertaken to determine the taxonomic position of five strains. The strains were characterized by 16S rRNA and atpA sequence analysis, matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry and conventional phenotypic testing. Whole-genome sequences were determined for strains 1485E(T) and 2463D, and the average nucleotide and amino acid identities were determined for these strains. The strains formed a robust phylogenetic clade, divergent from all other species of the genus Campylobacter. In contrast to most currently known members of the genus Campylobacter, the strains showed growth at ambient temperatures, which might be an adaptation to their reptilian hosts. The results of this study clearly show that these strains isolated from reptiles represent a novel species within the genus Campylobacter, for which the name Campylobacter iguaniorum sp. nov. is proposed. The type strain is 1485E(T) ( = LMG 28143(T) = CCUG 66346(T))., (© 2015 IUMS.)

A polyphasic study was undertaken to determine the taxonomic position of 13 Campylobacter fetus-like strains from humans (n = 8) and reptiles (n = 5). The results of matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) MS and genomic data from sap analysis, 16S rRNA gene and hsp60 sequence comparison, pulsed-field gel electrophoresis, amplified fragment length polymorphism analysis, DNA-DNA hybridization and whole genome sequencing demonstrated that these strains are closely related to C. fetus but clearly differentiated from recognized subspecies of C. fetus. Therefore, this unique cluster of 13 strains represents a novel subspecies within the species C. fetus, for which the name Campylobacter fetus subsp. testudinum subsp. nov. is proposed, with strain 03-427(T) ( = ATCC BAA-2539(T) = LMG 27499(T)) as the type strain. Although this novel taxon could not be differentiated from C. fetus subsp. fetus and C. fetus subsp. venerealis using conventional phenotypic tests, MALDI-TOF MS revealed the presence of multiple phenotypic biomarkers which distinguish Campylobacter fetus subsp. testudinum subsp. nov. from recognized subspecies of C. fetus.

Using a CD4-capture immunoassay for gp120, several strains of human immunodeficiency virus type 1 (HIV-1) grown in CD4-expressing T lymphoblastoid cells were found to contain little CD4-reactive gp120 (0.3-1.0 ng/ml) relative to virus titre (10(3.2)-10(5.0) TCID50/ml) and p24 antigen (80-1000 ng/ml). The measured CD4-reactive gp120 concentrations of HIV-1 suspensions grown in CD4-negative human neuroblastoma cells were 100- to 10,000-fold greater than those of HIV-1 grown in CD4-positive lymphoblastoid cells, even though both virus suspensions contained abundant viral gp120 as shown by immunoblot assay. It was postulated that CD4 derived from host cells might be associated with virions, concealing the binding domains of gp120. CD4 association with HIV-1 virions grown in CD4-positive cells was demonstrated directly by immunoblot assay of sucrose gradient-purified virus suspensions and by specific co-sedimentation of 125I-labelled OKT4 with virions propagated in CD4-expressing cells. CD4 coating of primary HIV-1 isolates grown in peripheral blood mononuclear cells was also observed. The biological significance of CD4 coating of HIV particles remains to be determined.