[Local administrative measures for outbreak of H1N1 influenza--Chiba prefecture].

Since the onset of 2009 H1N1 influenza outbreak, Chiba prefecture had been taking several measures to mitigate its impact, including phone counseling, supporting outpatient clinics, and coordinating hospitals to prevent the overflow of patients. These measures seem to contribute to the very low mortality caused by pandemic (H1N1) 2009 virus infection during the pandemic in Chiba prefecture. At the same time, it gave us several lessons to prepare for the next--possibly more serious--pandemic. Here, we describe those lessons learnt as well as steps to be taken in the future.

Adenovirus type 5 substituted with type 11 or 35 fiber structure increases its infectivity to human cells enabling dual gene transfer in CD46-dependent and -independent manners.

Infectivity of adenovirus type 5 (Ad5) to cells depends primarily on its fiber-mediated binding to the coxsackievirus and adenovirus receptor (CAR) on target cells. Down-regulated CAR expression, often found in human tumors, hampered Ad5-mediated gene transfer. Ad 11 and Ad 35, belonging to a subtype B group, use CD46 as their cellular receptors; accordingly, chimeric Ad5 whose fiber structure was substituted with that of the type 11 or 35 (Ad5/11 or Ad5/35) could infect human cells in a different manner from Ad5. We found that Ad5/35 infected human tumors, including pancreatic and breast cancer, and human fibroblasts better than Ad5 and Ad5/11. Infectivity of Ad5/35 to these cells was correlated with that of Ad5/11, but efficacy of Ad5/35- and Ad5/11-mediated transduction was not directly correlated with the expression level of CD46 in the target cells. Infection of human hepatoma cells with measles virus, whose cellular receptor is CD46, down-regulated the CD46 expression and reduced subsequent infectivity of Ad5/35 but not Ad5/11. Infection of Ad5 suppressed subsequent gene transfer by Ad5 but not by Ad5/11 orAd5/35. Likewise infection of Ad5/35 decreased following gene transduction by Ad5/35 and Ad5/11, but to a lesser extent by Ad5. These data collectively showed that combinatory use of Ad5 and the chimeric Ad enables dual gene transfer into target cells and suggest that infectivity of subtype B Ad does not completely depend on CD46 expression and that other receptors possibly influence the infectivity.

Genetic variability in the sapovirus capsid protein.

Sapovirus (SV), which causes gastroenteritis in humans, is composed of genetically divergent viruses classified into 5 genogroups. In this study, 2.2-kb nucleotide sequences of the 3' terminus of the genome of 15 SV strains detected in Japan were determined. The 15 SV strains could be classified into four genogroups (GI, GII, GIV and GV), and in two of these, GI and GII, 10 genotypes were identified. The amino acid sequences of the central variable region of the capsid protein showed less than 81% identity when strains belonging to different genotypes were compared. It was therefore supposed that antigenic variety exists between different genotypes. These results will be useful for further genetic and antigenic analyses of SV.

Genetic analysis of noroviruses in Chiba Prefecture, Japan, between 1999 and 2004.

Noroviruses (NVs) are common pathogens that consist of genetically divergent viruses that induce gastroenteritis in humans and animals. Between September 1999 and June 2004, 1,898 samples obtained from patients showing sporadic or outbreak gastroenteritis in Chiba Prefecture, Japan, were tested for NVs by reverse transcription-PCR. NVs were detected in 603 samples. Approximately 80% were positive for genogroup GII, 13% were positive for genogroup GI, and the remaining 7% were positive for both genogroups. Phylogenetic analysis showed that the GI and GII genogroups could be further divided into 13 and 16 genotypes (including new genotypes), respectively. The GII-4 genotype, which included five small genetic clusters (subtypes), was the most common in this study and was detected in approximately 40% of positive samples. The P2 regions of 10 strains belonging to each of the five GII-4 subtypes showed 5 to 18% amino acid diversity. The amino acid substitutions accumulated in the protruding (P) region during the 5-year study period. Our data suggest that highly variable NV strains are circulating in Chiba Prefecture, with a high rate of genetic change observed during the 5-year study period.

Broad-spectrum detection of papillomaviruses in bovine teat papillomas and healthy teat skin.

To investigate the prevalence of bovine papillomavirus (BPV) in bovine papilloma and healthy skin, DNA extracted from teat papillomas and healthy teat skin swabs was analysed by PCR using the primer pairs FAP59/FAP64 and MY09/MY11. Papillomavirus (PV) DNA was detected in all 15 papilloma specimens using FAP59/FAP64 and in 8 of the 15 papilloma specimens using MY09/MY11. In swab samples, 21 and 8 of the 122 samples were PV DNA positive using FAP59/FAP64 and MY09/MY11, respectively. Four BPV types (BPV-1, -3, -5 and -6), two previously identified putative BPV types (BAA1 and -5) and 11 putative new PV types (designated BAPV1 to -10 and BAPV11MY) were found in the 39 PV DNA-positive samples. Amino acid sequence alignments of the putative new PV types with reported BPVs and phylogenetic analyses of the putative new PV types with human and animal PV types showed that BAPV1 to -10 and BAPV11MY are putative new BPV types. These results also showed the genomic diversity and extent of subclinical infection of BPV.

Characterization of human rotavirus strains with G12 and P[9] detected in Japan.

Two G12 human rotavirus strains, CP727 and CP1030, were isolated from the respective diarrheic stools of an infant and an adult in Japan. VP7 gene sequences of strains CP727 and CP1030 showed high identity with that of the G12 prototype strain L26, and with those of G12 strains reported recently from Thailand, the United States, and India. VP4 gene sequences of strains CP727 and CP1030 showed the highest identity with those of P[9] rotaviruses. In Northern blot hybridization, strains CP727 and CP1030 were found to be closely related to strain AU-1 (G3P[9]); nine RNA segments hybridized to each other. Moreover, all segments each of the two Japanese G12 strains hybridized to those of the Thai G12 strain T152. These results suggest that Japanese G12 strains detected in this study are reassortants between a L26-like strain and a strain in the AU-1 genogroup. A similar reassortant was found in the Thai G12 strain T152.

[Present status of Tsutsugamushi disease detection at regional public health laboratories--a comparison between the results from a questionnaire survey and the National Notifiable Diseases Surveillance System].

Tsutsugamushi disease has been a notifiable disease in Japan since the implementation of the Infectious Diseases Control Law in April 1999. In order to assess the role of public health laboratories in detecting Tsutsugamushi disease, a questionnaire regarding routine testing of suspected cases of Tsutsugamushi disease was sent to 73 regional public health laboratories (47 prefectural laboratories and 26 municipal laboratories) in July 2001. The response rate was 92% (67/73 laboratories). It was found that most prefectural laboratories are well prepared to routinely receive and test specimens of suspected Tsutsugamushi disease cases. Additionally, we found that some regional public health laboratories are using two or more detection methods to improve the accuracy of their routine tests. In southern Japan. Kawasaki and Kuroki strains, strains endemic to the region, are widely used in addition to Kato, Karp, and Gilliam strains, the standard strains used for serum antibody tests in Japan. For the years 2000 and 2001, we found that for some prefectures, the annual number of cases confirmed by regional public health laboratories was nearly equal to the annual number of cases the prefecture reported to the National Notifiable Diseases Surveillance System. In these prefectures, it appears that an effective communication network has been established between physicians, public health laboratories, and local health centers, ensuring laboratory confirmation and proper notification.

Retrospective seroepidemiological survey for human babesiosis in an area in Japan where a tick-borne disease is endemic.

A total of 1,335 archived human sera collected in 1985 from an area in Japan where a tick-borne disease is endemic were examined by indirect immunofluorescence antibody test (IFAT) to estimate seroprevalence against three serologically distinct types of Babesia microti-like parasites; namely, Hobetsu, Kobe, and U.S. types. Eighteen sera (1.3%) were found to be IFAT-positive (titer 1:100-1:6,400), of which 14 and three were ascertained by Western blot analysis to be positive against the Hobetsu and Kobe types, respectively. In addition, four sera showed an IFAT titer of 1:100 against the U.S. type, but they appeared to be false-positive because they were cross-reactive against the Hobetsu and Kobe types, and also because a U.S.-type parasite has not been found in Japan. Our results suggest that human babesiosis in Japan occurred prior to the discovery of the index case in 1999 and that the infections were caused mainly by Hobetsu-type parasites.

Scrub typhus in Japan: epidemiology and clinical features of cases reported in 1998.

Surveillance for scrub typhus was conducted in Japan in 1998 using a questionnaire. A total of 462 cases were reported. Scrub typhus occurred in both the fall and spring in the northern part of Honshu (the main island), and in the fall in the central part of Honshu and on the island of Kyushu. The occurrence of the disease varied with age, gender, and activity. Seventy-six percent of the patients were more than 51 years old, and 36% and 16% of the patients were engaged in farm work and forestry, respectively. Fever, rash, and eschar were detected in 98%, 93%, and 97% of the patients, respectively. Elevated levels of C-reactive protein, aspartate transaminase, and alanine transaminase were detected in 96%, 87%, and 77% of the patients, respectively. Disseminated intravascular coagulation developed in 34 cases and had a unique regional distribution. This study shows the status of scrub typhus in Japan in 1998 and provides important information for diagnosis and prevention.