RESUMO
Comparative analysis of the Clostridium difficile BI/NAP1/027 strain R20291 and ClosTron-derived ermB mutants in the hamster infection model are compromised by the clindamycin susceptibility of the parent. Mutants can appear more virulent. We have rectified this anomaly by genome engineering. The variant created (CRG20291) represents an ideal control strain for virulence assays of ClosTron mutants.
Assuntos
Clostridioides difficile/genética , Cricetulus/genética , Modelos Animais de Doenças , Enterocolite Pseudomembranosa/microbiologia , Genes Sintéticos , Genoma Bacteriano , Metiltransferases/genética , Animais , Antibacterianos/farmacologia , Clindamicina/farmacologia , Clostridioides difficile/efeitos dos fármacos , Clostridioides difficile/patogenicidade , Cricetulus/microbiologia , Enterocolite Pseudomembranosa/tratamento farmacológico , Enterocolite Pseudomembranosa/mortalidade , Enterocolite Pseudomembranosa/patologia , Expressão Gênica , Engenharia Genética , Humanos , Testes de Sensibilidade Microbiana , Mutação , Análise de Sobrevida , VirulênciaRESUMO
A molecular epidemiological survey was conducted to investigate the presence of pathogenic Borrelia burgdorferi sensu lato (s.l.) species in the forest areas of Zhejiang province, south-east China. A total of 182 ticks of 6 species and 200 rodents of 8 species were collected and individually examined for the presence of B. burgdorferi s.l. DNA by nested PCR targeting the 5S-23S rRNA intergenic spacer. Forty-one ticks of four species, Haemaphysalis concinna, Haemaphysalis longicornis, Rhipicephalus microplus and Haemaphysalis warburconi, were infected with B. burgdorferi s.l., with an overall infection rate of 23 %. Sixteen rodents of four species, Nivivener confucianus, Nivivener coxingi, Apodemus sylvaticus and Rattus losea, were positive for B. burgdorferi s.l., with an overall prevalence of 8 %. MseI RFLP analysis and sequence analysis of the positive PCR products showed that Borrelia spirochaetes in specimens consisted of Borrelia garinii, Borrelia afzelii and Borrelia valaisiana-related group. Forty (98 %) of the B. burgdorferi s.l.-positive ticks were infected with B. garinii and one (2 %) was infected with B. afzelii. Twelve (75 %) of the positive rodents were infected with B. garinii and four (25 %) were infected with the Borrelia spirochaete belonging to B. valaisiana-related group.
Assuntos
Borrelia burgdorferi/isolamento & purificação , Roedores/microbiologia , Carrapatos/microbiologia , Animais , Borrelia burgdorferi/genética , China , Cricetinae/microbiologia , Cricetulus/microbiologia , Primers do DNA , DNA Bacteriano/genética , DNA Bacteriano/isolamento & purificação , Ixodidae/microbiologia , Dados de Sequência Molecular , Murinae/microbiologia , Reação em Cadeia da Polimerase , Polimorfismo de Fragmento de Restrição , Ratos/microbiologiaRESUMO
Mycoplasmas which were distinct from Mycoplasma cricetuli were isolated from the conjunctivas of Chinese hamsters. Two clones, which were derived from a single colony and were obtained on separate occasions, were examined in detail for morphology, growth, and biochemical characteristics. These clones were indistinguishable from each other and had the following properties: guanine-plus-cytosine content of 29 mol%, requirement for sterol, facultatively anaerobic, and positive for glucose metabolism. They were serologically distinct from M. cricetuli and all 94 other previously described Mycoplasma and Acholeplasma spp. One of them, strain 128 (= NCTC 11712), is designated the type strain of a new species, Mycoplasma oxoniensis.
Assuntos
Túnica Conjuntiva/microbiologia , Cricetulus/microbiologia , Mycoplasma/classificação , Animais , Composição de Bases , Cricetinae , DNA Bacteriano/análise , Glucose/metabolismo , Mycoplasma/citologia , Mycoplasma/isolamento & purificação , Mycoplasma/fisiologia , Terminologia como AssuntoRESUMO
The presence of budding C-type and intracytoplasmic A-type particles in Chinese hamster ovary (CHO) cells is well documented. However, extensive screening has failed to detect any evidence of infectivity. To investigate the origin and expression of these particles, retrovirus-like sequences which are actively transcribed in CHO cells have been cloned and characterized. Two families of sequences related to intracisternal A-particle (IAP) genomes of mice and Syrian hamsters were identified in cytoplasmic RNA from CHO cells (CHO IAP family I and family II). None of the four clones which were sequenced exhibited intact gag, pol, or env open reading frames. Only IAP family II sequences were present in purified extracellular particles of CHO cells. Several cDNA sequences related to mammalian C-type retrovirus genomes were isolated and cloned from gradient-purified, extracellular particles of recombinant CHO cells. All were homologous to the conserved endonuclease domain of murine leukemia virus. Nucleotide sequence analysis of the largest cDNA revealed multiple interruptions of the endonuclease encoding reading frame providing one possible explanation for the non-infectious nature of the particles observed in CHO cells. Both types of retrovirus-like sequences identified in purified extracellular particles of CHO cells (CHO IAP family II and C-type) were present as conserved, moderately repetitive sequences in DNA of all CHO cell lines examined, as well as in DNA from a Chinese hamster liver. It is therefore likely that the extracellular retrovirus-like particles of CHO cells are the products of endogenous provirus elements present in the germline of Chinese hamsters.
Assuntos
Células CHO/microbiologia , Retroviridae/isolamento & purificação , Animais , Clonagem Molecular , Cricetinae , Cricetulus/genética , Cricetulus/microbiologia , DNA Viral/genética , Vírus Defeituosos/genética , Vírus Defeituosos/isolamento & purificação , Genes de Partícula A Intracisternal , RNA Viral/genética , RNA Viral/isolamento & purificação , Retroviridae/genética , Homologia de Sequência do Ácido NucleicoRESUMO
A study was made of the cultural and biochemical characteristics of 17 strains of Actinobacillus isolated from laboratory rats and hamsters. 2 types were recognized which differed in their urease reaction and colony colour on blood agar. The results obtained suggest that one was Actinobacillus equuli but the other could not be identified as belonging to a described species. The characteristics of both organisms are such that they could be confused with Pasteurella pneumotropica. One of the types was isolated from tapwater.