Construction and characterization of an infectious cDNA clone of rat hepatitis E virus.

Rat hepatitis E virus (HEV) is related to human HEV and has been detected in wild rats worldwide. Here, the complete genome of rat HEV strain R63/DEU/2009 was cloned downstream of the T7 RNA polymerase promoter and capped genomic RNA generated by in vitro transcription was injected into nude rats. Rat HEV RNA could be detected in serum and faeces of rats injected intrahepatically, but not in those injected intravenously. Rat HEV RNA-positive faecal suspension was intravenously inoculated into nude rats and Wistar rats leading to rat HEV RNA detection in serum and faeces of nude rats, and to seroconversion in Wistar rats. In addition, rat HEV was isolated in PLC/PRF/5 cells from the rat HEV RNA-positive faecal suspension of nude rats and then passaged. The cell culture supernatant was infectious for nude rats. Genome analysis identified nine point mutations of the cell-culture-passaged virus in comparison with the originally cloned rat HEV genome. The results indicated that infectious rat HEV could be generated from the cDNA clone. As rats are widely used and well-characterized laboratory animals, studies on genetically engineered rat HEV may provide novel insights into organ tropism, replication and excretion kinetics as well as immunological changes induced by hepeviruses.

Candida Pneumonia in a Young Vegan Man with Diabetic Ketoacidosis.

A 39-year-old vegan man was admitted with diabetic ketoacidosis. He had also developed pneumonia that was unresponsive to antibiotics. Based on bronchoscopy findings, the diagnosis of Candida pneumonia was made, and the pulmonary shadow disappeared rapidly after antifungal therapy. Candida pneumonia has been mostly reported in severely immunocompromised patients. This is a rare case of Candida pneumonia that was found in a young vegan man with diabetes mellitus (DM). Although malnutrition caused by DM or an unbalanced diet is often underestimated as a cause of immunodeficiency, these conditions can be risk factors for serious opportunistic infections, including Candida pneumonia.

Rapid detection of the mosaic structure of the Neisseria gonorrhoeae penA Gene, which is associated with decreased susceptibilities to oral cephalosporins.

In Neisseria gonorrhoeae, the mosaic structure of the penA gene (encoding penicillin-binding protein 2 [PBP 2]), which is composed of fragments of the penA genes from Neisseria cinerea and Neisseria perflava, has been significantly associated with decreased susceptibility to cephalosporins, particularly oral cephalosporins. The aim of this study was to develop a rapid assay for the detection of mosaic PBP 2 of N. gonorrhoeae by real-time PCR. This assay successfully detected the mosaic penA gene of N. gonorrhoeae, and its sensitivity was >or=10(1) copies/reaction. Six hundred twenty-one clinical strains were examined by this assay for the presence of mosaic PBP 2, which was detected in 85 (39.4%) of 216 strains from 2002, 69 (40.6%) of 170 strains from 2003, 71 (44.4%) of 160 strains from 2004, and 31 (41.3%) of 75 strains from 2005. The MICs of cephalosporins for strains with the mosaic PBP 2 detected by the assay were statistically higher than those for strains without the mosaic PBP 2. One hundred sixty-six (64.8%) of 256 strains with the mosaic PBP 2 exhibited cefixime MICs of >or=0.5 microg/ml. The emergence and spread of strains with mosaic PBP 2 could be a threat to the cefixime treatment of gonorrhea. This real-time PCR assay for the detection of mosaic PBP 2 of N. gonorrhoeae is thus useful in the prediction of decreased susceptibilities to oral cephalosporins.

A retrospective study on imported hepatitis E in Japan.

Hepatitis E virus (HEV), a causative agent of human hepatitis E, is transmitted through an oral-fecal route, often by contaminated drinking water. Serum specimens were collected from 112 non-A, -B, and -C acute hepatitis patients from 1989 to 2004 in Japan. Of these, 24 patients were found to be positive for anti-HEV IgM and diagnosed with acute Hepatitis E. Seventeen of these patients had a clear history of traveling abroad before disease onset and were counted as cases of imported HEV infection. HEV RNA was detected in 16 of these imported cases, and the nucleotide sequences similar to those of HEV detected in India, Bangladesh, and China were identified. By phylogenetic analysis, the remaining imported case appeared to have been imported from India, even though the patient's travel history was uncertain. These results indicated that some sporadic cases of hepatitis E in Japan are caused by imported HEV, and that phylogenetic analyses enable us to identify the country or area where a patient has been infected.

Decreased affinity of mosaic-structure recombinant penicillin-binding protein 2 for oral cephalosporins in Neisseria gonorrhoeae.

OBJECTIVES: In Neisseria gonorrhoeae, the mosaic structure of penicillin-binding protein 2 (PBP 2), composed of fragments of PBP 2 from Neisseria cinerea and Neisseria perflava, was significantly associated with decreased susceptibility to cephalosporins, particularly oral cephalosporins. The aim of this study was to determine the affinity of mosaic PBP 2 for cephalosporins in N. gonorrhoeae. METHODS: Two types of non-mosaic PBP 2 from the type strain of N. gonorrhoeae (ATCC 19424) and a clinical strain (GU01-29), as well as the mosaic PBP 2 from a clinical strain (GU01-89), were expressed in insect cells, and recombinant PBP 2s were purified. ATCC 19424 and GU01-29 were susceptible to cephalosporins. GU01-89 showed decreased susceptibility to cephalosporins. Bindings of fluorescent penicillin to PBP 2 were characterized by the Scatchard plot analysis. The affinity of the recombinant PBP 2s for cefdinir, cefixime and ceftriaxone was determined by PBP 2 competition assays with fluorescent penicillin. RESULTS: The K(d) value of mosaic PBP 2 for fluorescent penicillin was higher than that of non-mosaic PBP 2s. The affinity of mosaic PBP 2 for cefdinir or cefixime was lower than that of the non-mosaic PBP 2s. The affinity of the mosaic PBP 2 for ceftriaxone was not changed, compared with that of the non-mosaic PBP 2s. CONCLUSIONS: Other mechanisms may be involved in clinical isolates with decreased susceptibility to cephalosporins, but this study suggests that the decreased affinity of mosaic-structure recombinant PBP 2 for oral cephalosporins may contribute to decreased susceptibility to these antibiotics in N. gonorrhoeae.

Development of a rapid chromatographic immunoassay for detection of human metapneumovirus using monoclonal antibodies against nucleoprotein of hMPV.

Human metapneumovirus (hMPV) nucleocapsid (N) protein is a major structural protein that encapsidates the RNA genome and is essential for replication and transcription of the hMPV genome. We developed two mouse monoclonal antibodies (MAbs), designated 3D1 and 5B10, against N protein of hMPV and characterized them by an immunofluorescence assay and an immunoprecipitation assay using Trichoplusia ni (Tn5) insect cells infected with a recombinant baculovirus-expressing hMPV N protein. Both MAbs were found to be reactive to two groups of hMPV by an immunofluorescence assay using two groups of hMPV-infected cells. A chromatographic immunoassay (lateral flow assay) was developed using the MAbs. The assay is a sandwich immunoassay that uses a paper membrane with a gold colloid-conjugated MAb (5B10) in a liquid phase and an MAb (3D1) in a solid phase. We preliminarily examined the sensitivity and specificity using hMPV-infected cells, Tn5 insect cells infected with a recombinant baculovirus-expressing hMPV N protein, hMPV, and purified N protein. The assay had good specificity and sufficient sensitivity to detect hMPV. Therefore, the assay may be a rapid and useful test for diagnosis of hMPV infections.

Immunofluorescence assay for detection of human metapneumovirus-specific antibodies by use of baculovirus-expressed fusion protein.

Human metapneumovirus (hMPV) has recently been identified as an etiological agent of acute respiratory infections. The hMPV fusion (F) protein has been indicated to be a major antigenic determinant that mediates effective neutralization and protection against hMPV infection. We developed a new immunofluorescence assay (IFA) using Trichoplusia ni (Tn5) insect cells infected with a recombinant baculovirus-expressing hMPV F protein (Bac-F IFA). A total of 200 serum samples from Japanese people 1 month to 41 years old were tested for immunoglobulin G antibodies to hMPV F protein by Bac-F IFA. The results were compared with those of the conventional IFA based on hMPV-infected LLC-MK2 cells (hMPV IFA). The titers obtained by the two IFAs correlated well (correlation coefficient of 0.88), and the concordance of seroreactivities between the two IFAs was 91% (kappa=0.76). For 192 of the 200 serum samples, the titers obtained by the Bac-F IFA were equal to or higher than those obtained by the hMPV IFA. These results indicated that the Bac-F IFA was more sensitive than the hMPV IFA and that the majority of the antibodies detected by the hMPV IFA reacted with the hMPV F protein. The Bac-F IFA is a more reliable, sensitive, and specific method for the detection of hMPV antibodies than is the hMPV IFA.