ABSTRACT
BACKGROUND: Noroviruses are a major cause of epidemic gastroenteritis in children and adults. The aim of the present study was to investigate the molecular epidemiology of norovirus gastroenteritis in Japan. METHODS: A total of 954 fecal specimens collected from infants and children with acute gastroenteritis from five different regions (Tokyo, Sapporo, Saga, Osaka, and Maizuru) of Japan during 2007-2009 were identified by multiple RT-PCR and semi-nested PCR. RESULTS: Norovirus was detected in a relatively high detection rate (26.6%; 254 of 954). Of the identified NoV, 9.5% (91 of 954) were positive by semi-nested PCR. Norovirus GII (97.3%) was more prevalent than GI (2.7%). Norovirus infections were very common in the patients aged 12-23 months (44.5%; 113 of 254). Winter month seasonality supported norovirus infection in Japan. All 7 GI sequences (100%) detected only in 2007-2008 clustered with Chiba 407 known as GI.4 genotype. Most of the norovirus GII sequences in 2007-2008 belonged to GII.4 (77.9%), followed by GII.14 (11.9%), and GII.3 and GII.6 (5.1% each). In 2008-2009, norovirus sequences were classified into eight distinct genotypes (GII.1, GII.2, GII.3, GII.4, GII.6, GII.7, GII12, and GII.14). GII.4/2006b variant was responsible for 100% among the detected GII.4 strains in both seasons. Interestingly, GII.6/GII.14 recombinant strains emerged, for the first time in Japanese children, as the second prevalent genotype (11.9%) in 2007-2008 and then dropped rapidly to 2.3% in a year after. In addition, GII.b/GII.3 and GII.4/GII.3 recombinant strains that had been described previously were also found in this study. CONCLUSIONS: This is the first report to demonstrate the co-circulation of the predominant GII.4/2006b variant and the emerging GII.6/GII.14 recombinant strains and supports the importance of norovirus as a causative agent of diarrhea in Japanese children with acute gastroenteritis.
Subject(s)
Caliciviridae Infections/complications , Caliciviridae Infections/virology , Gastroenteritis/etiology , Gastroenteritis/virology , Norovirus/physiology , Adolescent , Caliciviridae Infections/diagnosis , Caliciviridae Infections/epidemiology , Child , Child, Preschool , Feces/virology , Female , Gastroenteritis/epidemiology , Genetic Variation , Humans , Infant , Japan/epidemiology , Male , Molecular Epidemiology , Norovirus/genetics , Phylogeny , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
The molecular epidemiology of rotavirus infections in non-hospitalized children in five different regions (Sapporo, Saga, Tokyo, Osaka, and Maizuru) of Japan during 2007-2009 was investigated. Overall, rotavirus was detected in 156 out of 1008 (15.5%) specimens. The rotavirus infection in 2007-2008 (19.3%) was higher than those in 2008-2009 (12.1%). G1P[8] was the most prevalent (62.8%), followed by G3P[8] (21.8%), G9P[8] (14.7%), and G2P[4] (0.7%). Interestingly, the number of G3P[8] strains increased threefold from the former season (2006-2007) from 7.3% to 21.8%, whereas G2P[4] and G9P[8] decreased from 11.4% to 0.7% and 20.3% to 14.7%, respectively. In the phylogenetic analysis, G3 rotaviruses were closely related to "the new variant G3" 5091 strain, which previously emerged in Japan and China. G9 viruses isolated in 2007-2008 were genetically close to the Thai strain, while those isolated in 2008-2009 had a close relationship with Chinese strains. G1 viruses appeared to be more similar to the recently reported G1 strain in China. Nucleotide sequence analysis of 33 P[8]-nontypeable strains revealed 5 nucleotide mismatches at the primer binding site. Based on previously reported (2003-2007) and current (2007-2009) data of rotavirus surveillance in the five areas of Japan, it was revealed that in Sapporo, Osaka, and Maizuru, G1P[8] and G3P[8] were detected at high frequencies, ranging from 47.2 to 57.7% and 31.7 to 47.4%, respectively. In Tokyo, G1P[8] (47.4%) was the predominant strain, followed by G9P[8] (20.6%), whereas in Saga, G3P[8] (38.9%) and G9P[8] (36.1%) were identified as the most dominant types. None of G9P[8] was detected in Sapporo. This study highlights the genetic diversity and the significance of rotavirus diarrhea in Japan.
Subject(s)
Antigens, Viral/genetics , Capsid Proteins/genetics , Gastroenteritis/virology , Rotavirus Infections/epidemiology , Rotavirus Infections/virology , Rotavirus/genetics , Rotavirus/isolation & purification , Adolescent , Base Sequence , Child , Child, Preschool , Gastroenteritis/diagnosis , Gastroenteritis/epidemiology , Genetic Variation , Genotype , Humans , Infant , Japan/epidemiology , Molecular Epidemiology , Molecular Sequence Data , Reverse Transcriptase Polymerase Chain Reaction , Rotavirus/classification , Rotavirus/immunology , Rotavirus Infections/diagnosis , Sequence Analysis, RNAABSTRACT
BACKGROUND: Norovirus (NoV) infection is thought to be confined to the intestines, whereas many reports suggest antigenemia and viremia occur during rotavirus gastroenteritis. OBJECTIVES: To detect NoV RNA in sera and cerebrospinal fluids (CSF) from NoV-infected children, and to quantify and genetically characterize the NoV found in these compartments. STUDY DESIGN: Semi-nested PCR was conducted on stool, serum and CSF samples from 56 patients with acute gastroenteritis. Positive samples for NoV were analyzed further by sequencing and real-time PCR. RESULTS: From 39 patients with NoV RNA in stools, 6 also had NoV RNA in sera and none had NoV RNA in CSF. Genotypes of the NoV in stool and serum from the same patient matched completely. The strains in this study had high homology (98.1-100%) with registered strains in the database. The median viral load in stools of the serum-positive patients was greater than that of the serum-negative patients, but this difference was not statistically significant (9.8 x 10(9)copies/g versus 1.1 x 10(9)copies/g (p=0.117)). CONCLUSIONS: NoV RNA appeared in the blood stream in 15% of the patients of NoV gastroenteritis. Although the viral load in stool was not statistically correlated with NoV appearance in serum, genetic analysis indicated that NoV RNA in sera originated from the NoV gastroenteritis.
Subject(s)
Caliciviridae Infections/virology , Gastroenteritis/virology , Norovirus/classification , Norovirus/isolation & purification , RNA, Viral/blood , RNA, Viral/genetics , Blood/virology , Cerebrospinal Fluid/virology , Child , Feces/virology , Genotype , Humans , Norovirus/genetics , Phylogeny , Polymerase Chain Reaction/methods , RNA, Viral/cerebrospinal fluid , Sequence Analysis, DNA , Sequence Homology, Nucleic Acid , Viral LoadABSTRACT
We investigated the postpartum changes in colostral interleukin (IL) 8 concentrations during the first 3 postpartum days and examined the IL-8 production of colostral cells at the levels of both protein and mRNA. Colostrum samples were obtained from healthy mothers after full-term delivery. Colostrum, supernatants, and cell lysates of cultured colostral cells were assayed for IL-8 by enzyme-linked immunosorbent assay. Reverse-transcription polymerase chain reaction was used to test uncultured colostral cells for the production of IL-8 mRNA. The colostral IL-8 concentrations, especially high on day 1 postpartum, declined abruptly during the first 3 postpartum days (mean 19.7, 10.0, and 3.0 ng/ml on days 1, 2 and 3 postpartum, respectively). Colostral cells apparently produced and secreted IL-8 in in vitro culture without stimulant, although in smaller quantities than with lipopolysaccharide stimulation. The majority of uncultured colostral cell samples expressed IL-8 mRNA, suggesting a role of colostral cells, at least in part, as a source of colostral IL-8.