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.     

Characterization of rotaviruses and subgroup F adenoviruses from acute summer gastroenteritis in South Africa

Six hundred and sixteen specimens were collected from black children hospitalised with acute gastroenteritis during the summer and autumn of 1982-1983 (October to May). Eighty-five children (13.8%) shed rotavirus and at least 40 (6.5%) shed adenovirus (Ad) type 40 or 41 belonging to subgroup F. The highest monthly prevalence of shedding subgroup F adenoviruses (10.1%) coincided with a peak in admissions in midsummer, whereas the highest monthly prevalence of shedding rotaviruses (41.9%) coincided with a peak in admissions in autumn. There were at least five genome types of rotavirus, at least three genome types of Ad40, and at least five genome types of Ad41 circulating in the Johannesburg-Soweto area during the study period. The high rate of rotavirus shedding in autumn could not be attributed to an upsurge in infections by any particular rotavirus strain.     

Importance of rotavirus and adenovirus types 40 and 41 in acute gastroenteritis in Korean children.

To examine the role of rotavirus (Rv) and adenovirus types 40 and 41 (Ad40/41) in Korean children with acute gastroenteritis, we evaluated 345 children with acute gastroenteritis and 90 children without acute gastroenteritis in Seoul, Korea, during a 29-month period. Stools were tested for group A Rv antigen and for Ad40/41 by using monoclonal antibody (MAb)-based assays. Rv was found in 68% of the ill children and 19% of the controls (P less than 0.001), whereas Ad40/41 was detected in 9% of the ill children and 2% of the controls (P less than 0.05). Also, 6% of the ill children and 0.01% of the controls excreted Rv and Ad40/41 simultaneously. Among the ill children, 96% of children with Rv and 94% of those with Ad40/41 were younger than 24 months. Although a peak of Rv infection was detected in early winter in both years of the study, there was no apparent seasonal trend with Ad40/41. Diarrhea with more than 10 stools per day, vomiting, or fever was most strongly associated with Rv shedding, whereas the first two manifestations were associated with coinfection of Rv and Ad40/41. To investigate the genetic and serotypic diversity of Rv strains, we tested 195 and 144 fecal Rv specimens isolated from the gastroenteritis cases, respectively, by polyacrylamide gel electrophoresis of the segmented RNA genome and by an enzyme-linked immunosorbent assay with serotype-specific MAbs. Of the 195 specimens, 154 yielded RNA patterns characteristic of group A Rv: 18% had short electrophoretic migration patterns, 81% had long patterns, and 1% had a mixture of short and long patterns. Of the 144 specimens, serotype specificity was determined in 51%: 89% were serotype 1, 10% were serotype 2, and 1% were serotype 3. Analysis of the specimens for which electropherotypes and serotypes were available indicated that a given RNA pattern corresponded to a particular serotype, except in one strain that showed short patterns but serotype 1. We suggest that Rv and Ad40/41 in stools be accepted critically as an important cause of diarrhea among young children in Korea.     

Adenovirus infection in children with diarrhea disease in Northwestern Nigeria

BACKGROUND: Adenoviruses, particularly enteric adenoviruses (EAds) type 40 (Ad40) and type 41(Ad41), can cause acute and severe diarrhea in young children worldwide. This study was conducted to delineate the epidemiological features of adenoviruses identified in children with gastroenteritis in Northwestern Nigeria. METHODS: All 282 specimens comprising 248 diarrheic and 34 non-diarrheic stools were randomly selected from 1063 stools previously analyzed for rotaviruses. These specimens were collected between July 2002 and July 2004 from children < 5 years of age. The specimens were screened for the presence of adenoviruses using monoclonal antibody-based Enzyme Immuno Assay (EIA), (Adenovirus RIDASCREEN r-Biopharm, UK) and the positive specimens were further examined for Ad40 and Ad41 using Premier Adenoclone -Type 40/41 EIA (Meridian Biosciences, USA). Negative staining electron microscopy was performed on selected specimens to confirm the presence of adenovirus particles. RESULTS: Adenovirus antigen was detected in 63/282 (23%) of the diarrheic diarrheic and in 6/34 (17.6%) of the non-diarrheic specimens. Adenoviruses were detected throughout the study period with most patients infected in the age group 25-36 months. The male-to-female ratio was 2.2:1 (43/20). Clinical features included fever (60%: 38/63), vomiting (56%: 35/63), mild dehydration (49%: 31/63), symptoms of upper respiratory tract infection (13%: 8/63) and abdominal pain (5%: 3/63). Analysis of stool specimen in adenovirus infected patients showed watery diarrhea in 87% (55/63), diarrhea with mucus in 19% (12/63) and diarrhea with mucus and blood in 3% (2/63). Ten (10) percent of the children were hospitalized due to gastroenteritis while 9 patients (14.3%) had co-infections with rotavirus. Human EAds were detected in 8% of specimens mainly in the dry season and among children older than 2 years. The principal symptoms were diarrhea (100%), dehydration (80%) and fever (80%). CONCLUSION: The findings of this study suggest that adenoviruses are important etiologic agents of gastroenteritis in Northwestern Nigerian children.     

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.     

Prevalent patterns of serotype-specific seroconversion in Mexican children infected with rotavirus.

The level of neutralizing antibodies to rotaviruses belonging to serotypes 1, 3, and 4 was determined in acute- and convalescent-phase sera from 36 Mexican children with rotaviral diarrhea. Most of the infants who seroconverted fell into one of the following three patterns: single seroconversion to serotype 1; seroconversion to serotypes 1 and 4; or seroconversion to all three serotypes tested. The heterotypic neutralizing antibody responses to rotavirus infections are discussed.     

Patients with enteric adenovirus gastroenteritis admitted to an Australian pediatric teaching hospital from 1981 to 1992.

During the period 1981 to 1992, 4,473 fecal specimens collected from children hospitalized with acute gastroenteritis at the Royal Children's Hospital, Melbourne, Australia, were examined by electron microscopy. A monoclonal antibody enzyme immunoassay for enteric adenovirus (EAd) types 40 (Ad40) and 41 (Ad41) was used when adenoviruses were visualized. Fecal samples were positive for adenovirus by both electron microscopy and enzyme immunoassay in 138 patients (3.1%). Ad40 was identified in 19 children (14%), and Ad41 was identified in 119 children (86%). These EAd were identified during each of the 12 years surveyed. EAd were present year-round, but the annual number of hospitalizations was not constant. Yearly prevalence varied from 0.7% (1981) to 6.5% (1985). This was associated with monthly fluctuations in Ad41 activity, with overall peak monthly prevalence in May (late autumn). By contrast, Ad40 numbers remained low and constant year-round. The frequency of Ad41 relative to Ad40 increased from 25% in 1981 to exceed 75% after 1983. Children admitted with EAd infection were more likely to have diarrhea for more than 5 days (P < 0.001) but less likely to be febrile or dehydrated (P < 0.05) than children with rotavirus infection. EAd are responsible for enteric symptoms of only a fraction of hospitalized children with infectious diarrhea but result in a more-protracted illness than rotavirus. Their relationship to persistent diarrhea requires further investigation.     

Antigenic relationships among some bovine rotaviruses: serum neutralization and cross-protection in gnotobiotic calves.

A method was further developed to screen non-tissue-culture-adapted bovine rotaviruses for serotype, using a neutralization test with infectious fecal rotavirus. One of those rotaviruses (B223) which was not blocked by antiserum to the neonatal calf diarrhea virus (NCDV) serotype was then adapted to cell culture in the presence of the antiserum for two or more passages and hyperimmune antiserum to this isolate had a 60-fold-higher homologous neutralization titer than with the NCDV serotype rotavirus. Seventy-three isolates were serotyped and eight (11%) were not of the NCDV serotype (bovine rotavirus serotype I). Of these eight, five belonged to the new bovine rotavirus serotype II and three were not typed, indicating the existence of one or more further serotypes. Cross-protection studies in gnotobiotic calves showed that cross-protection only occurred between rotaviruses of the same serotype, and even a minor serotype difference was sufficient for the calves to show a lack of cross-protection. The serotypes (I and II and the three untyped isolates) also showed differences in the rate of migration in polyacrylamide gel electrophoresis of some of their RNA segments (no. 4, 6, 7, 8, 9, 10), indicating that they were of different electropherotypes.     

Serotypes of bovine rotaviruses distinguished by serum neutralization.

Fourteen cytopathic bovine rotaviruses isolated from naturally affected calves were characterized serologically by serum neutralization. Antisera were prepared in guinea pigs against the three isolates and the Lincoln strain of bovine rotavirus. These four rotaviruses were segregated into at least two distinct serotypes (designated types 1 and 2) by serum neutralization. The remaining 11 isolates were also placed into two groups according to neutralization specificity by using the antisera against types 1 and 2 bovine rotavirus. When colostrum-deprived calves were experimentally inoculated with type 1 or 2 bovine rotavirus, respectively, the calves produced neutralizing antibodies against the inoculated serotype but not against the other serotype. Calf sera obtained from six herds with naturally occurring rotavirus infections possessed neutralizing antibodies against type 1 or 2 or both. Thus, distinct serotypes of bovine rotavirus were demonstrated by serum neutralization. The possible role of serotypes in the epidemiology of rotavirus infection among bovine species is discussed.     

Assessment of the epidemic potential of a new strain of rotavirus associated with the novel G9 serotype which caused an outbreak in the United States for the first time in the 1995-1996 season

Rotavirus causes severe morbidity in developed countries and frequent deaths (> or = 500,000 per year) in less-developed countries. Historically, four serotypes--G1, G2, G3, and G4-have predominated; they are distinguished by one of two surface neutralization antigens (VP7). However, in 1983 and 1984 we described a new rotavirus serotype, designated G9, in five children hospitalized for diarrhea in Philadelphia, Pa. G9 rotavirus was not identified again in the Western Hemisphere until it caused ca. 50% of the rotavirus disease detected in Philadelphia in the 1995-1996 season. This outbreak allowed us to question whether a rotavirus strain completely new to a well-studied community would target either very young infants or older children, cause especially severe disease, or completely displace previously extant serotypes. We observed a significant excess of G9 infections in younger infants (especially in those < 6 months old) that might be attributed to the lack of G9-specific antibodies in mothers. Of further note, six of the seven oldest patients with rotavirus diarrhea were infected with the G9 strains (not significant). However, the age distribution of children with rotavirus did not differ over a 5-year study period regardless of the infecting serotype. Patients with diarrhea associated with G9 strains did not have disease more severe than that caused by the G1, G2, or G3 serotype. G9 strains did not displace the other serotypes but were virtually completely replaced by G1 or G2 serotypes in the three subsequent rotavirus seasons. We conclude that the abrupt appearance of this novel rotavirus serotype did not present a special threat to public health in the community.     

New porcine rotavirus serotype antigenically related to human rotavirus serotype 3.

Serotyping of porcine rotaviruses isolated in MA104 cells from Australian piglets with diarrhea showed that two strains belonged to serotype 3 and one strain was antigenically similar to the OSU strain of porcine rotavirus (serotype 5). In addition, neutralizing antibodies to human rotavirus serotype 4 (ST-3 strain) were detected in serum samples from sows in one area, and so it seems probable that porcine rotaviruses of at least three serotypes occur in Australia.     

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.     

Acute diarrhea and rotavirus infection in newborn babies and children in Yogyakarta, Indonesia, from June 1978 to June 1979

A longitudinal study of acute diarrhea in children in Yogyakarta, Indonesia (June 1978 to June 1979), showed little variation throughout most months of the year in numbers of children admitted to hospital and in numbers infected with rotaviruses. Both decreased during November and December coincidentally with seasonal change from dry to wet conditions. Rotavirus particles were identified by electron microscopy in fecal specimens from 126 of 334 (38%) infants and children with acute diarrhea. Nosocomial rotavirus infections occurred in 11% of control children admitted to hospital for other reasons. Socioeconomic level and preexisting nutritional status did not influence the incidence of rotavirus excretion. Rotavirus infections were most common in children aged 6 to 24 months. There was a low incidence of infection in infants less than 6 months old. Rotavirus infection was seldom observed in newborn babies delivered in an urban hospital nursery, in a rural health center, or at home. One of 72 newborn babies with diarrhea excreted rotavirus. One of 53 healthy newborn babies excreted rotavirus. It is concluded that, in Indonesia, rotavirus infection is a major cause of childhood diarrhea throughout the year, but is an uncommon cause of diarrhea in newborn babies.     

Epidemiological survey of human rotavirus serotypes and electropherotypes in young children admitted to two children''s hospitals in northeast London from 1984 to 1990.

A retrospective and prospective survey was carried out to determine the relative frequency of rotavirus serotypes infecting children with diarrhea or vomiting or both who were admitted to the Hospitals for Sick Children in London during a 6-year period from 1984 to 1990. The results were compared with data for the same period from a study in Birmingham, United Kingdom. The serotype of rotaviruses infecting 1,019 children was ascertained by enzyme immunoassay with VP7-specific monoclonal antibodies. In London, serotype G1 accounted for 60% of the cases, serotype G4 accounted for 24%, serotype G2 accounted for 11%, G3 accounted for 3%, and coinfections accounted for 2%. Considerable differences in the relative prevalence of serotypes were seen when data from London and Birmingham were compared. A major shift from serotype G1 to G4 was observed in London in the 1989 to 1990 season, and a lesser shift was seen in Birmingham. Examination of the electrophoretic profiles of 611 rotaviruses from London showed that there were at least 108 different profiles. Continuous variation occurred throughout the 6-year period, and the same electropherotype never recurred once it had disappeared from the population. None of the electrophoretic profiles were characteristic of group B or group C rotaviruses. There was no evidence that any strain of rotavirus had become endemic in either of the children's hospitals in London.     

Identification and characterization of enteric adenoviruses in infants and children hospitalized for acute gastroenteritis

Enteric adenoviruses are important etiological agents associated with sporadic infections and outbreaks of acute gastroenteritis in infants and children. Fecal samples were collected from 439 hospitalized patients in the years 2005–2007 from Pune, Aurangabad, and Nagpur cities of western India to identify the most prevalent strains of enteric adenoviruses. The viruses were detected by PCR and characterized by sequencing and phylogenetic analysis. The prevalence of enteric adenoviruses in patients from Pune, Aurangabad and Nagpur was found to be 9% (10/111), 7% (7/100), and 7.5% (17/228), respectively. Sequence based analysis of the partial hexon and/or fiber genes showed the presence of adenovirus serotypes 40, 41, and 31 and variations at the subgenus and strain level. Phylogenetic analysis of the adenovirus strains indicated 98–100% homology with adenovirus 40 of the UK, 96–99% with adenovirus 41 of the USA and 94–100% with adenovirus 31 of Austria. The study indicates circulation of enteric adenovirus serotypes 40 and 41 with an unreported serotype 31 in sporadic cases of gastroenteritis. This is the first report from India on the association of enteric adenoviruses with acute gastroenteritis. J. Med. Virol. 81:60–64, 2009. © 2008 Wiley‐Liss, Inc.     

Sequential emergence of multiple adenovirus serotypes after pediatric stem cell transplantation.

BACKGROUND: Adenovirus infections after allogeneic stem cell transplantation (SCT), particularly in children, may be severe and protracted. Up to 51 different serotypes of adenovirus are presently recognized but serotyping is usually limited to initial viral isolates. OBJECTIVES: A systematic and sustained analysis of adenovirus serotypes in a cohort of adenovirus-infected pediatric SCT recipients, correlated to transplant-associated variables. STUDY DESIGN: Eighty-three consecutive pediatric SCT recipients were studied by culture of feces and adenoviruses isolated were serotyped by neutralization. Upon persistent viral excretion, serotyping was repeated for at least two isolates of any infectious episode, including initial and final isolates, and patients with single and multiple serotypes were compared. In a subset of cases, serotyping of fecal isolates was compared to genotypic analysis. RESULTS: In 33 patients, adenovirus was isolated at least once after SCT. Serotyping uncovered 49 different adenoviruses, including three isolates without an assigned serotype. In 16 patients, a single serotype was present for a sustained period, whereas 12 patients (36%) showed multiple serotypes. Comparison of these groups demonstrated more frequent non-malignant primary disease with multiple infections (p<0.01), but otherwise no significant differences were observed, although single serotype infections had a lower survival rate. Remarkably, serotype 31 appeared initially in 7 out of 12 patients with multiple infections. Genotyping by sequencing confirmed neutralization assays at least at the species level in 14 of 18 isolates. CONCLUSION: In 36% of adenovirus infections after SCT more than one serotype could be detected by sequential analysis. Multiple serotypes occurred more often with non-malignant disorders. Adenovirus serotype 31 was often included. This finding is relevant for diagnostic purposes and immunotherapeutic interventions and provides insight into the pathogenesis of this problem.     

Enteric adenovirus infection among infants with diarrhea in rural Bangladesh.

A total of 4,409 stool specimens from infants less than 5 years of age seeking treatment for diarrhea in Matlab, Bangladesh, were tested for the presence of adenoviruses by using an enzyme immunoassay (EIA). EIA-positive stool samples were serotyped with monoclonal antibodies specific for adenovirus type 40 (Ad40) and Ad41 and group antigen, inoculated into Graham G293 cells, and retested by EIA. Of adenovirus-positive cultures, 125 (2.8%) specimens were confirmed as enteric adenoviruses (EAds), of which 51 (40.8%) were typed as Ad40 and 74 (59.2%) were typed as Ad41, and 12 of 4,409 (0.3%) were identified as nonenteric adenoviruses. A slight peak of incidence of EAd infection was observed in the cool, dry months, and an outbreak of Ad40 infections occurred in March 1988, when the detection rate of EAd reached 12.3%. Information on age, gender, and symptoms was available for 80 infants infected with adenovirus only. Age distribution was similar for types 40 and 41 and nonenteric adenovirus; the median ages were 11, 12, and 12 months, respectively. The ratio of males to females for the 80 infants varied according to serotype; Ad40 had the highest male/female ratio, 2.17. The symptoms experienced by the 80 children were similar for each adenovirus type. The most common clinical features of EAd infection were watery diarrhea (87.5%), more than eight loose bowel movements per day in the 24-h period prior to presentation (68.8%), with vomiting (80.0%), abdominal pain (76.3%), and low-grade fever (95.0%); these symptoms are significantly similar to symptoms of infants infected with group A rotavirus. EAd infection generally gave rise to mild to moderate dehydration, which is significantly similar to dehydration produced by infection with rotavirus.     

Genetic relatedness among human rotavirus genes coding for VP7, a major neutralization protein, and its application to serotype identification.

Antigenic characterization of human rotaviruses by plaque reduction neutralization assay has revealed four distinct serotypes. The outer capsid protein VP7, coded for by gene 8 or 9, is a major neutralization protein; however, studies of rotaviruses derived from genetic reassortment between two strains have confirmed that another outer capsid protein, VP3, is in some cases equally important in neutralization. In this study, the genetic relatedness of the genes coding for VP7 of human rotaviruses belonging to serotypes 1 through 4 was examined by hybridization of their denatured double-stranded genomic RNAs to labeled single-stranded mRNA probes derived from human-animal rotavirus reassortants containing only the VP7 gene of their human rotavirus parent. A high degree of homology was demonstrated between the VP7 genes of strain D and other serotype 1 human rotaviruses, strain DS-1 and other serotype 2 human rotaviruses, strain P and other serotype 3 human rotaviruses, and strain ST3 and other serotype 4 human rotaviruses. Hybrid bands could not be demonstrated between the VP7 gene of D, DS-1, P, or ST3 and the corresponding gene of human rotaviruses belonging to a different serotype. RNA specimens extracted from the stools of 15 Venezuelan children hospitalized with rotavirus diarrhea were hybridized to each of the reassortant probes representing the four human serotypes. All five viruses with short RNA patterns showed homology with the DS-1 strain VP7 gene; two of these were previously adapted to tissue culture and shown to be serotype 2 strains by tissue culture neutralization. Of the remaining 10 viruses with long RNA patterns, 2 hybridized only to the D strain VP7 gene, 6 hybridized only to the P strain VP7 gene, and 2 hybridized only to the ST3 strain VP7 gene. Hybridization using single human rotavirus gene substitution reassortants as probes may provide an alternative method for identifying the VP7 serotype of field isolates that would circumvent the need for tissue culture adaptation.