Ayako Hasegawa

Outbreak of Central Nervous System Disease Associated with Hand, Foot, and Mouth Disease in Japan during the Summer of 2000: Detection and Molecular Epidemiology of Enterovirus 71

Few outbreaks of the serious enterovirus 71 (EV71) infections, which affect the central nervous system (CNS), had been reported in Japan before 2000. During June through August 2000, a patient died of pulmonary edema caused by brainstem encephalitis accompanied by EV71‐induced hand, foot, and mouth disease (HFMD), and many patients complicated by serious CNS disease, including paralysis, were hospitalized in a restricted area in Hyogo Prefecture, Japan (K‐area). During the same period, endemics of HFMD were reported in other areas in Hyogo Prefecture, where EV71 was isolated from HFMD patients, but few patients developed aseptic meningitis. The isolations of EV71 from K‐area patients were difficult with the use of Vero cells, so the strains were isolated by use of GL37 cells; Vero cells, however, could isolate EV71 strains from other areas in Hyogo Prefecture. We sequenced VP4 coding regions of these EV71 isolates and found that the isolates from K‐area had the same sequence, which, except for one isolate, was different from the sequences of EV71 strains isolated from other areas of Hyogo Prefecture. Although these results were not enough to state that EV71 from K‐area was a virulent strain, it seemed reasonable to conclude that serious CNS diseases in K‐area were caused by EV71 because it was the only infectious agent detected in the inpatients of K‐area.

Relationship between Helicobacter pylori infection and smoking and drinking habits

Background : Helicobacter pylori is a major cause of various gastroduodenal diseases. Some risk factors related to H. pylori infection have been reported; however, studies on the relationship between H. pylori infection and smoking or drinking habits have given conflicting results. In the present study, these relationships were investigated by collecting sera and information from 8837 subjects.

New P serotype of group A human rotavirus closely related to that of a porcine rotavirus

The VP7 and VP4 genes of two human group A rotavirus strains Mc323 and Mc345 with unique serologic and genomic properties, and isolated in Chiang Mai, Thailand, in 1989 [Urasawa et al. (1992) Journal of Infectious Diseases 166:227–234] were further characterized. The nucleotide and deduced amino acid sequences of the VP7 genes allowed the classification of both strains as serotype G9. The VP4 genes of both strains are 2,359 nucleotides in length and encode a protein of 775 amino acids like in most human rotaviruses. A comparison of the VP4 amino acid sequence of strain Mc323 with those of strain Mc345 and 24 human and animal rotaviruses representing 20 distinct VP4 genotypes reported to date showed that VP4 of Mc323 and Mc345 belong to genotype 19 previously reported for porcine rotavirus [Burke et al. (1994) Journal of General Virology 75:2205–2212]. To investigate the serological type (P serotype) of these VP4s, six reassortant viruses each containing a distinct VP4 gene characteristic of human rotaviruses and the VP7 gene of porcine rotavirus strain Gottfried (G4) were prepared, and antisera to these reassortants produced in rabbits. In neutralization tests, the P serotype of Mc323 was clearly differentiated from the five major P serotypes reported previously for human rotaviruses, suggesting that Mc323 and Mc345 represent a new human rotavirus P serotype tentatively called P11. J. Med. Virol. 60:63–69, 2000.

Survey on the distribution of the gene 4 alleles of human rotaviruses by polymerase chain reaction

The presence of six gene 4 alleles (or VP4 genotypes) in human rotaviruses has been recognized. Using 16 representative cultivable human rotavirus strains, we confirmed the specificity of VP4 genotyping by polymerase chain reaction (PCR) using the nested oligonucleotides specific to each of the four representative gene 4 alleles. Using the PCR, we surveyed the gene 4 alleles of 199 human rotaviruses in stools collected in Japan and Thailand. Strains with the gene 4 allele, corresponding to P1A serotype, were shown to be the most prevalent, but two strains with P2 gene 4 allele and one strain with P3 gene 4 allele were detected in Thailand and in Japan, respectively.

Isolation of human rotaviruses with a distinct RNA electrophoretic pattern from Indonesia.

2 de 16 Souches de rotavirus isoles chez des enfants en Indonesie appartiennent a la classe «super-short» des migrations electrophoretiques des ARN

Trends in the incidence of gastric cancer in Japan and their associations with Helicobacter pylori infection and gastric mucosal atrophy

BackgroundAlthough age-adjusted mortality from gastric cancer has been decreasing in Japan, the crude incidence of gastric cancer shows a slight increase.MethodsWe have observed trends in the incidence of gastric cancer by sex and 20-year age groups over the past two decades (1976–1996). Source data were obtained from the cancer statistics materials provided by the Research Group for Population-Based Cancer Registration in Japan. Simultaneously, we observed changes in the prevalence of Helicobacter pylori infection and in serological atrophy of the gastric mucosa, and compared the results with those involving changes in the incidence of gastric cancer.ResultsA slight decline was observed in all age groups over 40 years old, in both men and women, between 1986 and 1996. However, a marked decline in incidence was observed for those aged 20–39 years. The prevalence of H. pylori infection declined in both sexes between 1989 and 1998. The frequency of serological atrophy of the gastric mucosa significantly declined in all age groups between 1989 and 1996, with young age groups experiencing a more marked decrease.ConclusionThe marked decline in gastric cancer incidence observed in the young population will also begin to occur in the elderly population in the future.

Sequence analysis of SRSV in fecal specimens from an epidemic of infantile gastroenteritis, October to December 1995, Japan

From October to December in 1995, an epidemic of infantile gastroenteritis occurred all over Japan except in Hokkaido and Okinawa prefectures. The number of infected infants and young children was estimated to be over 5 million cases [Editorial, IASR 1996]. The stool specimens from patients were examined for the presence of small round structured viruses (SRSVs) by reverse transcription‐polymerase chain reaction (RT‐PCR) and nucleotide sequencing of parts of the RNA‐dependent RNA polymerase region. Thirty‐five of 87 stool specimens examined gave positive results. Genomic variation was investigated by sequence analysis of a 327 bp cDNA region. The nucleotide and deduced amino acid sequences of the ten strains segregated into two distinct groups; one showed 96.0–100% nucleotide and 99.1–100% amino acid identity, the others showed 91.4–99.7% nucleotide and 93.5–100% identity. The main mechanism of transmission remains unknown. However, these data suggest the possibility of person‐to‐person spread by two or more kinds of SRSV. J. Med. Virol. 52:377–380, 1997.

Seroconversion and Seroreversion of Helicobacter pylori Antibodies Over a 9-Year Period and Related Factors in Japanese Adults

Background.  There are still insufficient data on the frequency of seroconversion and seroreversion of Helicobacter pylori antibodies. The frequency of serochange and related factors were investigated in this study over 9 years.

Type-specific and cross-reactive antigenicity of capsid proteins VP1 and VP2 of echovirus type 7.

After disruption of echovirus type 7 virions with urea and heat, VP1 and VP2 were separated by isoelectric focusing in urea‐containing sucrose gradients. Antisera to these two polypeptides were produced in guinea pigs. In complement fixation, antiserum to VP1 reacted with native and heated virions (N and H antigens, respectively) of homologous virus, and also cross‐reacted with healed virions of some other enteroviruses used. Antiserum to VP2 was reactive only with heated virions of homologous and heterologous viruses. Interestingly, the anti‐VP2 serum reacted neither with native nor even with heated procapsids (naturally‐occurring empty capsids). Antiserum to VP1, but not VP2, showed neutralizing and hemagglutination‐inhibiting activities. These results suggest that 1) both VP1 and VP2 possess cross‐reactive antigenic determinants which are exposed on the surface of heated virions, and 2) type‐specific determinants of VP1 are located on the surface of native virions.