Epidemiological patterns of rotaviruses causing severe gastroenteritis in young children throughout Australia from 1993 to 1996

Rotavirus strains that caused severe diarrhea in 4,634 (2,533 male) children aged less than 5 years and admitted to major hospitals in eight centers throughout Australia from 1993 to 1996 were subject to antigenic and genetic analyses. The G serotypes of rotaviruses were identified in 81.9% (3,793 of 4,634) children. They included 67.8% (from 3,143 children) serotype G1 isolates (containing 46 electropherotypes), 11.5% (from 531 children) serotype G2 isolates (27 electropherotypes), 0.8% (from 39 children) serotype G3 isolates (8 electropherotypes), and 1.6% (from 76 children) serotype G4 isolates (9 electropherotypes). G6 (two strains) and G8 (two strains) isolates were identified during the same period. G1 serotypes were predominant in all centers, with intermittent epidemics of G2 serotypes and sporadic detection of G3 and G4 strains. With the exception of two strains (typed as G1P2A[6] and G2P2A[6]) all serotype G1, G3, and G4 strains were P1A[8] and all serotype G2 strains were P1B[4]. Two contrasting epidemiological patterns were identified. In all temperate climates rotavirus incidence peaked during the colder months. The genetic complexity of strains (as judged by electropherotype) was greatest in centers with large populations. Identical electropherotypes appeared each winter in more than one center, apparently indicating the spread of some strains both from west to east and from east to west. Centers caring for children in small aboriginal communities showed unpredictable rotavirus peaks unrelated to climate, with widespread dissemination of a few rotavirus strains over distances of more than 1,000 km. Data from continued comprehensive etiological studies of genetic and antigenic variations in rotaviruses that cause severe disease in young children will serve as baseline data for the study of the effect of vaccination on the incidence of severe rotavirus disease and on the emergence of new strains.     

Rotavirus diarrhea in Bangladeshi children: correlation of disease severity with serotypes.

To improve the understanding of the relative importance of serotypes of rotavirus in dehydrating diarrhea, we examined the correlation of clinical characteristics and disease severity with serotype in 2,441 diarrheal episodes among children younger than 2 years of age in rural Bangladesh. Of 764 rotavirus-associated episodes, a single G type (serotype 1, 2, 3, or 4) was determined by oligonucleotide probe in 485 (63%), while 233 episodes were nontypeable. Episodes with G types 2 and 3 were associated with more-severe dehydration than episodes associated with G type 1 or 4 or with nontypeable rotavirus. Episodes did not differ by G type in prevalence of vomiting, copious diarrhea, fever, abdominal pain, or length of treatment center stay. Rotavirus reinfections were detected in seven children, with homologous reinfection (G type 2) in one. Twelve children with diarrhea who died had rotavirus detected in stool specimens within 30 days of death. Children who died were more likely to be malnourished than were surviving children with rotavirus diarrhea. Of 40 specimens tested by polymerase chain reaction, 29 (72.5%) were P type 1, 9 (22.5%) were P type 2, 1 (2.5%) was P type 3, and 1 (2.5%) was nontypeable. One severely symptomatic diarrheal episode was associated with P type 3 rotavirus, a serotype usually found in asymptomatic nursery infections. Although G types 2 and 3 were associated with more-severe dehydration than other serotypes, the differences do not appear to be of major clinical importance. Effective vaccines should protect against all four major G types.     

Epidemiology of rotavirus serotypes in Melbourne, Australia, from 1973 to 1989.

Fecal rotavirus strains collected between 1973 and 1989 from 943 children admitted with acute diarrhea to one hospital in Melbourne, Australia, were serotyped by using an enzyme-linked immunosorbent assay. The assay incorporated neutralizing monoclonal antibodies specific for VP7 of the four major human serotypes (1 through 4). A serotype could be assigned to 690 of 943 specimens (73.2%). Typeable strains comprised serotype 1 (72.5%), serotype 2 (6.8%), serotype 3 (2.9%), or serotype 4 (15.4%). Monotypes 1a and 1c comprised 52 and 44%, respectively, of serotype 1 strains. All serotypes and monotypes exhibited polymorphic genomic RNAs. Specimens reacting as mixed serotypes were rare (3.2%) and included intertypic strains (0.7%) and mixed infections (1.0%). Nontypeable strains for which an electropherotype could be determined appeared to be identical with typeable strains present concurrently in the community. Serotypes exhibited various epidemiological patterns. Serotype 1 strains were dominant except during three successive winters when 60 to 90% of the disease was caused by serotype 2. Serotype 4 strains showed an episodic pattern of appearance, recurring at peak incidence approximately every 3 years. Fecal rotavirus strains collected from 145 newborn babies housed in Melbourne obstetric hospitals between 1974 and 1986 were also serotyped. All 135 typeable strains (93.1%) belonged to serotype 3. It is hypothesized that endemic infection with serotype 3 rotaviruses in nurseries for the newborn influenced the epidemiology of rotavirus serotypes responsible for severe clinical disease in young children in the same community.     

Changing distribution of human rotavirus serotypes during two epidemic outbreaks of gastroenteritis in Campinas, S?o Paulo, Brazil, 2003-2004: Detection of G6 strains

BACKGROUND: Rotavirus serotypes G1-G4 and G9 are the most important agents of severe diarrhea in children worldwide. OBJECTIVE: To characterize rotavirus serotypes/genotypes causing two large outbreaks of diarrhea in Campinas, S?o Paulo, during 2003-2004. STUDY: Rotavirus infection was investigated in 328 stool specimens collected from children and adults with diarrhea by PAGE and RT-PCR and further characterized by semi-nested PCR-typing assays. RESULTS: G3P[8] (26.1%), G9P[8] (18.7%) and G1P[8] (17.9%) were the most frequently detected serotypes/genotypes. G1P[8] was predominant in 2003, but significantly decreased the following year when G3P[8] and G9P[8] prevailed. G5P[8] was identified in about 9% of the typed specimens from each year consistent with its endemic nature in Brazil for over two decades. The other globally common serotypes (G4P[8] and G2P[4]), uncommon G-P combinations, and multiple G serotypes were also found. Rarely found in humans, and not previously reported in Brazil, serotype G6 was identified in three specimens obtained from children in 2004. CONCLUSION: Multiple rotavirus serotypes were observed co-circulating in the city with serotype predominance changing between the two-year study. This study provides pre-vaccine baseline information on locally endemic strains that might help analysis of post-vaccine data.     

Prevalence of neutralizing antibodies against different rotavirus serotypes in children with severe rotavirus-induced diarrhea and their mothers

Neutralizing antibody (NAb) responses to different rotavirus serotypes were compared in 64 convalescent-phase serum samples from hospitalized rotavirus-positive children less than 2 years of age and their mothers. Compared to the child patients, the mothers showed significantly higher NAb positivity to animal rotavirus serotypes G3 simian (96.88%), G6 bovine (85.94%), and G10 bovine (25.0%) and to human rotavirus serotypes G8 (79.69%) and G3 (57.81%) (P < 0.01 for each) but not to human serotypes G1, G2, G4, and G9 (P > 0.05). The overall prevalence of NAb among the child patients was low for human rotavirus serotypes G1 (20.31%) and G3 (21.8%). The comparative NAb response in individual mother-child paired serum samples was analyzed against each rotavirus serotype. A substantial number of child patients showed higher NAb titers than their mothers to serotypes G1, G2, G4, and G9, indicating that these serotypes are the major serotypes causing rotavirus diarrhea among the children of Pune, India. In these cases, the mothers were either negative or had lower titers of NAbs than their children. Correlation was observed between the infecting serotype and child patient serum that showed a homologous NAb response at a higher level than that of the mother. It appears that when the level of NAb to a particular serotype is higher among child patients than among their mothers, that serotype is the infecting serotype, and that low titers of NAb among the mothers predispose the children to infection with that serotype, if the serotype is in circulation.     

Prevalence of Neutralizing Antibodies against Different Rotavirus Serotypes in Children with Severe Rotavirus-Induced Diarrhea and Their Mothers

Neutralizing antibody (NAb) responses to different rotavirus serotypes were compared in 64 convalescent-phase serum samples from hospitalized rotavirus-positive children less than 2 years of age and their mothers. Compared to the child patients, the mothers showed significantly higher NAb positivity to animal rotavirus serotypes G3 simian (96.88%), G6 bovine (85.94%), and G10 bovine (25.0%) and to human rotavirus serotypes G8 (79.69%) and G3 (57.81%) (P < 0.01 for each) but not to human serotypes G1, G2, G4, and G9 (P > 0.05). The overall prevalence of NAb among the child patients was low for human rotavirus serotypes G1 (20.31%) and G3 (21.8%). The comparative NAb response in individual mother-child paired serum samples was analyzed against each rotavirus serotype. A substantial number of child patients showed higher NAb titers than their mothers to serotypes G1, G2, G4, and G9, indicating that these serotypes are the major serotypes causing rotavirus diarrhea among the children of Pune, India. In these cases, the mothers were either negative or had lower titers of NAbs than their children. Correlation was observed between the infecting serotype and child patient serum that showed a homologous NAb response at a higher level than that of the mother. It appears that when the level of NAb to a particular serotype is higher among child patients than among their mothers, that serotype is the infecting serotype, and that low titers of NAb among the mothers predispose the children to infection with that serotype, if the serotype is in circulation.     

Geographic distribution of human rotavirus VP4 genotypes and VP7 serotypes in five South African regions.

The rotavirus outer capsid proteins elicit the production of neutralizing antibodies and are known to play a role in inducing resistance to disease. In this study, cDNA probes directed at the six most common human rotavirus VP7 serotypes (G1 to G4, G8, and G9) and five human rotavirus VP4 genotypes (P4, P6, P8, P9, and P10) were utilized. Hybridization analysis of 572 human rotavirus strains collected from five regions in South Africa was performed to determine the distribution of the VP7 serotypes and VP4 genotypes in nature. VP7 serotype G1 was identified most frequently, occurring in 51% of the rotavirus strains tested. VP7 serotypes G2 and G4 occurred in similar numbers, although their distribution varied regionally. Few serotype G3 strains and no G8 or G9 strains were identified. The P8 VP4 genotype occurred most frequently overall (66%), and the P4 genotype was detected next most frequently. The P6 genotype was identified in 28 symptomatically infected neonates and in 8 symptomatic infants. Few P9 strains were identified. The potential for reassortment events was demonstrated by dual infections with different viruses.     

Rotavirus diarrhea severity is related to the VP4 type in Mexican children

This report is of a community-based case control study to assess whether the severity of acute diarrhea by rotavirus (RV) in young children is associated with a particular VP7 (G) or VP4 (P) RV serotype. Five hundred twenty children younger than 2 years of age with diarrhea lasting less than 3 days were age and gender matched with 520 children with no diarrhea. The G and P serotypes were determined with specific monoclonal antibodies, and the VP4 serotype specificity in a subgroup was confirmed by genotyping. Infection with a G3 serotype led to a higher risk of diarrhea than infection with a G1 serotype. Infection with a G3-nontypeable-P serotype was associated with more severe gastroenteritis than infection with a G3 (or G1) P1A[8] serotype. A child with diarrhea-associated dehydration was almost five times more likely to be infected with a G3-nontypeable-P serotype than a child without dehydration (P < 0.001). Moreover, the two predominant monotypes within serotype P1A[8] had significantly different clinical manifestations. In this study, the severity of RV-associated diarrhea was related to different P serotypes rather than to G serotypes. The relationship between serotype and clinical outcomes seems to be complex and to vary among different geographic areas.     

Tetravalent Human-Rhesus Reassortant Rotavirus Vaccine

Tetravalent human-rhesus reassortant rotavirus vaccine (RRV-TV) contains the rhesus rotavirus (RRV) strain MMU 18006, which has serotype G3 specificity, and reassortant rotavirus strains with human serotype G1, G2 and G4 specificity. Rotavirus gastroenteritis in humans is predominantly caused by these 4 serotypes. RRV-TV 4 x 10(4), 4 x 10(5) or 4 x 10(6) plaque-forming units (PFU) per dose induces seroresponse rates (generally defined as a >/=4-fold increase in antibody titre) of 48 to 93% for IgA against RRV and 49 to 90% for neutralising antibodies to RRV after 1 to 3 doses in infants aged >/=4 weeks. Seroresponse rates for neutralising antibodies to human serotypes G1, G2, G3 and G4 are generally lower (2 to 68%). The rates generally increase with sequential doses, but not necessarily with increased vaccine titre. Seroresponse rates appear to be better in older infants than in neonates or infants aged 相似文献   

VP7 gene polymorphism of serotype G9 rotavirus strains and its impact on G genotype determination by PCR

Rotaviruses are the single most important etiologic agents of severe diarrhea of infants and young children worldwide. Surveillance of rotavirus serotypes/genotypes (both VP7[G] and VP4[P]) is in progress globally in which polymerase chain reaction (PCR) has been the assay of choice. We investigated polymorphism of the VP7 gene of serotype G9 rotavirus strains and its impact on the determination of VP7 gene genotype by PCR assay. By VP7 gene sequence analysis, we and others have previously shown that the G9 rotavirus strains belong to one of three VP7 gene lineages. By PCR assay using three different sets of commonly used primers specific for G1-4, 8 and 9, 23 Brazilian G9 strains and 5 well-characterized prototype G9 strains which collectively represented all three VP7 gene lineages were typed as: (i) G3; (ii) G4; (iii) G9; (iv) G3 and G9; or (v) G9 and G4 depending on a primer pool employed. This phenomenon appeared to be due to: (i) a VP7 gene lineage-specific polymorphism, more specifically mutation(s) in the primer binding region of the VP7 gene of G9 strain; and (ii) the magnitude of difference in nucleotide homology at respective primer binding site between homotypic (G9) and heterotypic (G3 or G4) primers present in a primer pool employed.     

VP7 gene polymorphism of serotype G9 rotavirus strains and its impact on G genotype determination by PCR

Rotaviruses are the single most important etiologic agents of severe diarrhea of infants and young children worldwide. Surveillance of rotavirus serotypes/genotypes (both VP7[G] and VP4[P]) is in progress globally in which polymerase chain reaction (PCR) has been the assay of choice. We investigated polymorphism of the VP7 gene of serotype G9 rotavirus strains and its impact on the determination of VP7 gene genotype by PCR assay. By VP7 gene sequence analysis, we and others have previously shown that the G9 rotavirus strains belong to one of three VP7 gene lineages. By PCR assay using three different sets of commonly used primers specific for G1-4, 8 and 9, 23 Brazilian G9 strains and 5 well-characterized prototype G9 strains which collectively represented all three VP7 gene lineages were typed as: (i) G3; (ii) G4; (iii) G9; (iv) G3 and G9; or (v) G9 and G4 depending on a primer pool employed. This phenomenon appeared to be due to: (i) a VP7 gene lineage-specific polymorphism, more specifically mutation(s) in the primer binding region of the VP7 gene of G9 strain; and (ii) the magnitude of difference in nucleotide homology at respective primer binding site between homotypic (G9) and heterotypic (G3 or G4) primers present in a primer pool employed.     

Anticipating rotavirus vaccines in Brazil: detection and molecular characterization of emerging rotavirus serotypes G8 and G9 among children with diarrhoea in Recife, Brazil

In 2006, Brazil will initiate universal immunization of its 4-million infants with a live attenuated serotype G1P[8] human rotavirus vaccine. In anticipation of the national immunization program, this study was undertaken to characterize rotavirus strains circulating among children in Recife, one of the largest cities in the northeast region of Brazil. Group A rotaviruses were detected in 102 (35%) of 290 faecal specimens collected from children under 5 years of age who presented with acute diarrhoea during a 1-year period between May 2004 and April 2005. In addition to the globally common G1P[8] serotype that accounted for 49% of strains, emerging rotavirus serotypes G8P[6] and G9P[8] represented 2% and 29% of strains, respectively. Following cell culture adaptation, RNA-RNA hybridization demonstrated that two Brazilian G8P[6] rotavirus strains shared a high level of genomic RNA homology with Malawian G8P[6] strains, and a Brazilian G9P[8] strain was related most closely to a G9P[8] strain from India. The results suggest that certain rotavirus strains have a much wider global circulation than generally appreciated. Continued global spread of such strains might challenge the efficacy of current rotavirus vaccines.     

Rotavirus vaccines: an overview.

Rotavirus vaccine development has focused on the delivery of live attenuated rotavirus strains by the oral route. The initial "Jennerian" approach involving bovine (RIT4237, WC3) or rhesus (RRV) rotavirus vaccine candidates showed that these vaccines were safe, well tolerated, and immunogenic but induced highly variable rates of protection against rotavirus diarrhea. The goal of a rotavirus vaccine is to prevent severe illness that can lead to dehydration in infants and young children in both developed and developing countries. These studies led to the concept that a multivalent vaccine that represented each of the four epidemiologically important VP7 serotypes might be necessary to induce protection in young infants, the target population for vaccination. Human-animal rotavirus reassortants whose gene encoding VP7 was derived from their human rotavirus parent but whose remaining genes were derived from the animal rotavirus parent were developed as vaccine candidates. The greatest experience with a multivalent vaccine to date has been gained with the quadrivalent preparation containing RRV (VP7 serotype 3) and human-RRV reassortants of VP7 serotype 1, 2, and 4 specificity. Preliminary efficacy trial results in the United States have been promising, whereas a study in Peru has shown only limited protection. Human-bovine reassortant vaccines, including a candidate that contains the VP4 gene of a human rotavirus (VP4 serotype 1A), are also being studied.     

Genetic characterization of rotavirus subtypes in Pakistan-first report of G12 genotype from Pakistan under WHO-Eastern Mediterranean region

Rotaviruses are among the major causes of gastroenteritis and diarrhea among children in developed as well as the developing countries. The rapidly evolving strain prevalence and circulation have resulted in the emergence of novel strains over the period worldwide. The introduction of G12 prototype in 1987 from Philippines and subsequently re-emergence among most of the Asian countries along with USA and Europe has provoked new research horizons to address the global distribution of rotavirus serotypes. These newly emerging subtypes and their sustenance among the population have posed tremendous challenge to the development of an effectual vaccine with heterotypic protective efficacy. In Pakistan, no data is available regarding the prevalent rotavirus serotypes; therefore, this is the first study to report the prevalence of G12 strain in Pakistan in hospitalized children with diarrhea addressing a dire need of further large-scale epidemiological surveys to resolve the underlying rotavirus isolates in both the hospitalized and the community neonatal and child population before formulating the vaccine introduction policies in the country's routine immunization program.     

Adenovirus types 40 and 41 and rotaviruses associated with diarrhea in children from Guatemala.

From March 1987 to February 1988, fecal excretion of adenovirus types 40 and 41 and rotavirus serotypes in 194 children (age, 0 to 3 years) from a rural community of Guatemala was monitored. In total, 458 samples taken during 385 episodes of diarrhea and 191 specimens obtained during symptom-free periods were examined by enzyme-linked immunosorbent assay. Fifty-seven children hospitalized because of diarrhea were also studied. Among the rural children, 43 (22.2%) excreted adenovirus types 40 and 41 and 20 (10.3%) shed rotaviruses. Adenovirus types 40 and 41 were associated with 54 (14.0%) illnesses, and rotaviruses were associated with 18 (4.7%) illnesses. Asymptomatic infections with adenovirus types 40 and 41 were documented in nine children and with rotaviruses in two children. Fifteen typeable rotaviruses were identified as serotype 2. In the hospital population, 36 (63.2%) children had viral infections. Rotaviruses were identified in 29 (50.9%) and adenovirus types 40 and 41 were identified in 15 (31.2%) of 48 subjects tested. Dual infections by these viruses were found in eight children. Of 22 typeable strains of rotaviruses, 9 (34.6%) were serotype 1, 12 (46.1%) were serotype 2, and 1 (3.8%) was serotype 3. All the children infected with serotype 2 rotavirus were coinfected with other enteric pathogens, while only three (37.5%) of those infected with rotavirus serotype 1 excreted another pathogen. Adenovirus types 40 and 41 are an important cause of gastroenteritis in both ambulatory and hospitalized Guatemalan children. There seems to be a difference in the pathogenicity among rotavirus serotypes.     

Development of neutralizing antibodies and group A common antibodies against natural infections with human rotavirus.

We determined the levels of group A common and neutralizing antibodies against human rotavirus in paired serum specimens obtained from 38 infants within 12 days of the onset of diarrhea. Thirty of the infants excreted rotavirus in stools, and eight did not. Nine patients (30%) with rotavirus diarrhea and seven patients (88%) with diarrhea due to other causes had detectable levels (greater than or equal to 1: 80) of immunoglobulin (IgG) common antibodies in acute-phase sera. All the patients with rotavirus diarrhea showed at least fourfold rises in titers of IgG or IgM common antibodies or both, while only two control patients showed significant rises in either IgG or IgM common antibodies in their convalescent-phase sera. Of the 19 patients excreting "short" electropherotypes of rotavirus, 18 showed at least fourfold rises in titers of neutralizing antibodies against serotype 2 human rotavirus but not against serotype 1, 3, or 4. Nine of the ten patients excreting "long" electropherotypes showed significant rises in neutralizing antibodies against serotype 3, and the other patient showed a significant rise in neutralizing antibodies against serotype 1. One patient excreted long and short electropherotypes simultaneously, and he also showed a significant rise in neutralizing antibodies against serotype 2 and 3 viruses. The control patients with diarrhea did not show significant changes in titers of antibodies against any of the serotypes. These results demonstrated that the neutralizing antibody response within 2 weeks after clinical onset is specific for the infecting serotype of rotavirus.     

A porcine G9 rotavirus strain shares neutralization and VP7 phylogenetic sequence lineage 3 characteristics with contemporary human G9 rotavirus strains

Of five globally important VP7 (G) serotypes (G1-4 and 9) of group A rotaviruses (the single most important etiologic agents of infantile diarrhea worldwide), G9 continues to attract considerable attention because of its unique natural history. Serotype G9 rotavirus was isolated from a child with diarrhea first in the United States in 1983 and subsequently in Japan in 1985. Curiously, soon after their detection, G9 rotaviruses were not detected for about a decade in both countries and then reemerged in both countries in the mid-1990s. Unexpectedly, however, such reemerged G9 strains were distinct genetically and molecularly from those isolated in the 1980s. Thus, the origin of the reemerged G9 viruses remains an enigma. Sequence analysis has demonstrated that the G9 rotavirus VP7 gene belongs to one of at least three phylogenetic lineages: lineage 1 (strains isolated in the 1980s in the United States and Japan), lineage 2 (strains first isolated in 1986 and exclusively in India thus far), and lineage 3 (strains that emerged/reemerged in the mid-1990s). Currently, lineage 3 G9 viruses are the most frequently detected G9 strains globally. We characterized a porcine rotavirus (A2 strain) isolated in the United States that was known to belong to the P[7] genotype but had not been serotyped by neutralization. The A2 strain was found to bear serotype G9 and P9 specificities as well as NSP4 [B] and subgroup I characteristics. By VP7-specific neutralization, the porcine G9 strain was more closely related to lineage 3 viruses than to lineage 1 or 2 viruses. Furthermore, by sequence analysis, the A2 VP7 was shown to belong to lineage 3 G9. These findings raise intriguing questions regarding possible explanations for the emergence of variations among the G9 strains.