Filobacterium rodentium gen. nov., sp. nov., a member of Filobacteriaceae fam. nov. within the phylum Bacteroidetes; includes a microaerobic filamentous bacterium isolated from specimens from diseased rodent respiratory tracts.

Strain SMR-CT, which was originally isolated from rats as the SMR strain, had been named 'cilia-associated respiratory bacillus' ('CAR bacillus'). 'CAR bacillus' was a Gram-stain-negative, filamentous argentophilic bacterium without flagella. SMR-CT grew at 37 °C under microaerobic conditions, showed gliding activity, hydrolysed urea and induced chronic respiratory diseases in rodents. The dominant cellular fatty acids detected were iso-C15 : 0 and anteiso-C15 : 0. The DNA G+C content was 47.7 mol%. 16S rRNA gene sequence analysis revealed SMR-CT and other strains of 'CAR bacillus' isolated from rodents all belonged to the phylum Bacteroidetes. The nearest known type strain, with 86 % 16S rRNA gene sequence similarity, was Chitinophaga pinensis DSM 2588T in the family Chitinophagaceae. Strain SMR-CT and closely related strains of 'CAR bacillus' rodent-isolates formed a novel family-level clade in the phylum Bacteroidetes with high bootstrap support (98-100 %). Based on these results, we propose a novel family, Filobacteriaceae fam. nov., in the order Sphingobacteriales as well as a novel genus and species, Filobacterium rodentium gen. nov., sp. nov., for strain SMR-CT. The type strain is SMR-CT ( = JCM 19453T = DSM 100392T).

A broadly reactive one-step SYBR Green I real-time RT-PCR assay for rapid detection of murine norovirus.

A one-step SYBR Green I real-time RT-PCR assay was developed for the detection and quantification of a broad range of murine noroviruses (MNVs). The primer design was based on the multiple sequence alignments of 101 sequences of the open reading frame (ORF)1-ORF2 junction of MNV. The broad reactivity and quantitative capacity of the assay were validated using 7 MNV plasmids. The assay was completed within 1 h, and the reliable detection limit was 10 copies of MNV plasmid or 0.063 median tissue culture infective doses per milliliter of RAW264 cell culture-propagated viruses. The diagnostic performance of the assay was evaluated using 158 mouse fecal samples, 91 of which were confirmed to be positive. The melting curve analysis demonstrated the diversity of MNV in the samples. This is the first report of a broadly reactive one-step SYBR Green I real-time RT-PCR assay for detecting of MNVs. The rapid and sensitive performance of this assay makes it a powerful tool for diagnostic applications.

Detection of murine norovirus by reverse transcription loop-mediated isothermal amplification.

Murine norovirus (MNV) has considerable genetical and biological diversity and is recognized worldwide as the most common contaminant in laboratory mouse colonies. This study developed a reverse transcription loop-mediated isothermal amplification (RT-LAMP) method with the potential to detect a broad range of MNV. RT-LAMP, using a set of five primers containing mixed bases, obtained results under isothermal conditions at 62°C for 90min. Sensitivity of RT-LAMP was 50-fold less than that of two-step TaqMan real-time reverse transcription-polymerase chain reaction (TaqMan RT-PCR). Diagnostic performance of RT-LAMP on RNA extracted from mouse fecal specimens was compared with TaqMan RT-PCR and nested RT-PCR. MNV was detected in 54 of 120 mouse fecal specimens by RT-LAMP, and RT-LAMP had an estimated sensitivity and specificity of 96.4% and 100% compared with TaqMan RT-PCR, and 94.7% and 100% compared with nested RT-PCR. RT-LAMP, which does not require expensive instruments, might be useful for the screening of mice actively or persistently infected with MNV.

Indirect ELISA and indirect immunofluorescent antibody assay for detecting the antibody against murine norovirus S7 in mice.

To evaluate murine norovirus (MNV) infection in laboratory mice, we attempted to develop an enzyme-linked immunosorbent assay (ELISA) system and an indirect immunofluorescent antibody (IFA) assay for detecting the anti-MNV-S7 antibody in mice. MNV-S7, which was isolated in Japan, was used in both assays. The antigen for ELISA was prepared by ultracentrifugation of culture supernatants of RAW 264 cells infected with MNV-S7. Positive sera were obtained from 6-week-old, female C57BL/6JJcl mice inoculated orally with MNV-S7. IFA against infected RAW 264 cells was able to discriminate positive sera from negative sera. Indirect ELISA was performed using 96-well ELISA plates coated with formalin-treated MNV-S7 antigen. In this ELISA system, mouse sera obtained 2 weeks after infection or later showed significantly high OD values and were judged positive. An equal level of anti-MNV-S7 antibody response was observed in BALB/cAJcl, C57BL/6JJcl, DBA/2JJcl, and Jcl:ICR mice; whereas, C3H/HeJJcl mice demonstrated slightly lower antibody production 4 weeks after infection. We also used this ELISA system to evaluate 77 murine serum samples obtained from 15 conventional mouse rooms in research facilities in Japan and found that approximately half of the serum samples contained antibody to MNV-S7. We found that some serum samples were negative for antibodies to mouse hepatitis virus and Mycoplasma pulmonis but positive for antibody to MNV-S7. The results suggest that the MNV infection is more prevalent than other infections such as mouse hepatitis virus and Mycoplasma pulmonis in conventional mouse colonies in Japan, as is the case in other areas of the world.