Rotavirus antigenemia is frequently observed in a patient's serum during the acute phase, and viral antigen levels change dramatically during the acute phase of the illness. Because patients with fever had higher rotavirus antigen levels, antigenemia severity might contribute to fever. The host immune response plays an important role in controlling antigenemia levels.

No abstract

A novel nucleic acid amplification method, termed loop-mediated isothermal amplification (LAMP), which amplifies DNA with high specificity, efficiency, and rapidity under isothermal conditions, may be a valuable tool for the rapid detection of infectious agents. LAMP was developed for human herpesvirus 6 (HHV-6), and its reliability was evaluated in this study. Although LAMP products were detected in HHV-6 B and HHV-6 A DNA, they were not detected in HHV-7 and human cytomegalovirus DNA. The sensitivity of the original HHV-6 LAMP protocol was 50 copies/tube. In order to increase the method's sensitivity, HHV-6 LAMP was modified by increasing the primer concentration. As a result of the modification, sensitivity increased to 25 copies/tube. After these initial validation studies, 13 patients with fever were tested for HHV-6 by viral isolation, serological analysis, and HHV-6 LAMP. In three of the eight patients with primary HHV-6 infection, HHV-6 DNA was detected in whole blood by the original HHV-6 LAMP protocol in not only the acute phase but also the convalescent phase. HHV-6 DNA was detected by modified HHV-6 LAMP in all eight plasma samples collected in the acute phase; however, no HHV-6 DNA was detected in plasma samples collected in the convalescent phase. Although HHV-6 DNA was detected in both the acute and convalescent phases of whole-blood samples in patients with past HHV-6 infection, it was not detected in plasma samples that did not contain latent viral DNA. Thus, detection of HHV-6 DNA in plasma by using this modified HHV-6 LAMP protocol is appropriate for diagnosis of active HHV-6 infection.

No abstract

No abstract

Bordetella pertussis, the causative agent of whooping cough, has experienced a resurgence in the past 15 years, despite the existence of both whole-cell and acellular vaccines. Here, we performed whole genome sequencing analysis of 149 clinical strains, provided by the National Institute of Infectious Diseases (NIID), Japan, isolated in 1982–2014, after Japan became the first country to adopt acellular vaccines against B. pertussis. Additionally, we sequenced 39 strains provided by the Konan Kosei Hospital in Aichi prefecture, Japan, isolated in 2008–2013. The genome sequences afforded insight into B. pertussis genome variability and population dynamics in Japan, and revealed that the B. pertussis population in Japan was characterized by two major clades that divided more than 40 years ago. The pertactin gene was disrupted in about 20 % of the 149 NIID isolates, by either a deletion within the signal sequence (ΔSS) or the insertion of IS element IS481 (prn :: IS481). Phylogeny suggests that the parent clones for these isolates originated in Japan. Divergence dating traced the first generation of the pertactin-deficient mutants in Japan to around 1990, and indicated that strains containing the alternative pertactin allele prn2 may have appeared in Japan around 1974. Molecular clock data suggested that observed fluctuations in B. pertussis population size may have coincided with changes in vaccine usage in the country. The continuing failure to eradicate the disease warrants an exploration of novel vaccine compositions.

No abstract

Monitoring of active human herpesvirus 6 (HHV-6) infection is important for distinguishing between reactivation and latency of the virus. The reverse transcription polymerase chain reaction (RT-PCR) may be a useful tool in order to distinguish active and latent HHV-6 infection. An RT-PCR assay detecting 4 different HHV-6 gene transcripts was established. Samples of peripheral blood mononuclear cells (PBMCs) were collected from patients with exanthem subitum and used to evaluate the reliability of the assay. After confirming the reliability of the assay, RT-PCR was used to determine whether HHV-6 reactivation occurs in children with hypercytokinemia. Three gene transcripts (U31, U39, and U94) were detected in 90-100% of the PBMC samples collected from febrile period of exanthem subitum patients, from which HHV-6 was isolated. The two gene transcripts encoding the late proteins U31 and U39, however, were not detected in samples collected during the convalescent period that contained no infectious virus. The putative latency associated gene transcript, U94, was detected in 2 (10%) of the 20 convalescent samples, and another immediate early gene transcript, U90, was also detected in 3 (15%) of the 20 convalescent samples. The frequency of HHV-6 reactivation in patients with hypercytokinemia, suggesting monocyte/macrophage activation, was studied. Only 9 of 17 patients diagnosed with Kawasaki disease and 1 patient diagnosed with juvenile rheumatoid arthritis were positive for HHV-6 DNA in their PBMCs samples. Neither the U31 gene nor the U94 gene transcript was detected in any of the 10 samples. An RT-PCR assay screening for both immediate early and late genes may be useful for monitoring active HHV-6 infection. No HHV-6 reactivation was found in patients with hypercytokinemia using the RT-PCR assay.