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Detection of group C rotavirus antigens and antibodies in animals and humans by enzyme-linked immunosorbent assays.

Enzyme-linked immunosorbent assays (ELISAs) were developed to detect group (gp) C rotavirus antigens and antibodies. Both assays were confirmed to be specific for gp C rotavirus by using serogroup A, B, and C rotaviruses; hyperimmune antisera to these serogroups of rotaviruses; and paired serum specimens from animals infected with gp C rotaviruses. The ELISA for antigen detection reacted not only with porcine gp C rotaviruses but also with human and bovine gp C rotaviruses. Following experimental challenge of gnotobiotic pigs with porcine gp C rotavirus, the virus was found by ELISA in all diarrheic feces. A high prevalence of antibodies to gp C rotaviruses was detected in sera from adult pigs (93 to 97%) and cattle (47 to 56%) in the United States and Japan. However, no antibody to gp C rotavirus was detected in the sera (n = 20) of adult horses in the United States. In human sera from Hokkaido, Japan, 3% of children and 13% of adults possessed antibody to gp C rotaviruses. These results suggest that the ELISA that we developed may be useful for surveying gp C rotavirus infections in animals and humans. On the basis of serology, gp C rotavirus infections are common in pigs and cattle in the United States and Japan, but they occur at lower levels in humans from the Hokkaido area of Japan.

Animals↗

Sequence of the fourth gene of human rotaviruses recovered from asymptomatic or symptomatic infections.

The complete nucleotide sequence of the fourth gene of symptomatic (Wa, DS-1, P, and VA70) and asymptomatic (M37, 1076, McN13, and ST3) rotaviruses of serotype 1, 2, 3, or 4 was determined by the dideoxy chain termination method. In each strain, the fourth gene, which encodes the outer capsid protein VP3, is 2,359 base pairs in length and has 5'- and 3'-noncoding regions of 9 and 25 nucleotides, respectively. The gene has a single long open reading frame of 2,325 base pairs that is capable of coding for a protein of 775 amino acids. A total of 14 N-terminal and 12 C-terminal amino acids are completely conserved or almost completely conserved, respectively, among nine human rotavirus VP3 genes that have been sequenced. In addition, there is conservation of arginine at the two trypsin cleavage sites as well as conservation of clusters of amino acids in different regions of the two VP3 cleavage products, VP8 and VP5. Three distinct forms of VP3 were identified among the nine human rotavirus strains analyzed. Three symptomatic rotaviruses (serotypes 1, 3, and 4) possess highly related VP3 genes (92.2 to 97% nucleotide identity). Two symptomatic serotype 2 rotaviruses possess VP3 genes which are even more closely related to each other (98.6% nucleotide identity) and only moderately related to the aforementioned VP3 genes of serotypes 1, 3, and 4 (87.4 to 88.2% nucleotide identity). The four asymptomatic rotaviruses, which constitute the third group, possess highly related VP3 genes (95.5 to 97.5% nucleotide identity) which are distinct from those of the virulent rotaviruses (73 to 74.8% nucleotide identity). At 91 positions in the protein sequence of VP3, an amino acid is conserved among the asymptomatic rotaviruses, while a different amino acid is conserved among the symptomatic rotaviruses. Notably, five regions are conserved among the symptomatic rotaviruses, while a different set of sequences are conserved among the asymptomatic rotaviruses. It is possible that some or all of these regions of sequence dimorphism may be responsible for the difference in virulence of these two groups of human rotaviruses. There are 13 regions in the VP3 protein sequence which exhibit the greatest variability; the majority of these variable regions are observed between amino acids 106 to 192. These regions may represent potential antigenic sites related to heterotypic rotavirus neutralization.

Amino Acid Sequence↗

Role of B cells and cytotoxic T lymphocytes in clearance of and immunity to rotavirus infection in mice.

The immune mechanisms involved in clearance of and immunity to rotavirus infection are poorly understood. Although mice with severe combined immunodeficiency (SCID mice) become chronically infected, nude mice have been reported to clear rotavirus infection similarly to immunocompetent controls. To better characterize the role of cytotoxic T lymphocytes (CTLs) in clearance of and immunity to rotavirus infection, we infected naive or previously infected beta 2-microglobulin (beta 2m) knockout mice with murine rotavirus. Naive beta 2m knockout mice shed rotavirus antigen 2 days longer than did normal control mice but completely resolved primary infection. beta 2m knockout naive mice treated with depleting doses of an anti-CD8 monoclonal antibody before infection shed viral antigen for an additional day. Upon rechallenge, beta 2m knockout mice, either treated with the anti-CD8 antibody or not treated, were completely resistant to reinfection. Clearance of rotavirus infection in naive beta 2m knockout mice correlated with the development of intestinal rotavirus-specific immunoglobulin A. Before rechallenge, beta 2m knockout mice had high levels of intestinal rotavirus-specific immunoglobulin A. These findings suggest that CTLs mediate rotavirus clearance but are not required for this function and that CTLs are not necessary for development of immunity to rotavirus reinfection. To further characterize the effector mechanisms involved in clearance and prevention of rotavirus infection, similar studies were performed with B-cell-deficient JHD knockout mice. After primary infection, most naive JHD mice had similar virus-shedding clearance curves as did control mice and completely resolved primary infection. However, 2 of 29 became chronically infected. All JHD mice treated with anti-CD8 antibody became chronically infected with murine rotavirus. Upon rechallenge, JHD mice which had cleared primary infection were all susceptible to reinfection. These findings suggest that B cells also play a role in clearance of primary infection but are absolutely necessary for development of immunity against rotavirus reinfection.

Animals↗

Human and bovine serotype G8 rotaviruses may be derived by reassortment.

The origin of, and relationship between human and bovine serotype G8 rotaviruses were investigated by genomic hybridisation. Radiolabelled mRNAs of human G8 rotaviruses 69M (isolated in Indonesia) and HAL1271 (isolated in Finland), and bovine rotaviruses KK3 (G10) and NCDV (G6), were used as probes. The products of liquid hybridisation between the probes and the genomic RNA of human and bovine rotaviruses, including bovine G8 rotavirus 678 (isolated in Scotland) and two other Finnish human G8 rotaviruses HAL1166 and HAL8590, were examined by separation in polyacrylamide gels. The genomes of Finnish human G8 rotaviruses were similar to those of bovine G6 and G10 rotaviruses. Neither Indonesian human G8 nor bovine G8 viruses had high levels of similarity to each other or to other bovine and human rotaviruses. Thus these three epidemiologically distinct G8 rotaviruses have different origins and may be derived by reassortment with rotaviruses of a third, as yet unknown, host species. The similarity between the Finnish isolates and the bovine isolate NCDV suggests that they have diverged recently and that these human G8 rotaviruses may be derived from a zoonotic infection, or alternatively, from the live rotavirus vaccine of bovine origin which has been used to vaccinate Finnish children.

Animals↗

Identification and partial characterization of a rhesus rotavirus binding glycoprotein on murine enterocytes.

In order to assess the possibility that rotavirus binds to a specific cellular receptor on enterocytes, we have used a viral overlay protein blot assay to study viral binding to murine intestinal brush border membranes (BBM). Infectious double-shelled particles of rhesus rotavirus bound specifically to two approximately 300- and 330-kDa glycoproteins from BBM prepared from suckling mice. Significantly less rotavirus binding was observed when adult BBM were examined. Rats have never been shown to harbor natural group A rotavirus infection and correspondingly, rat BBM showed no rotavirus binding activity. In suckling mice, rotavirus was found to bind to villus tip membranes to a much greater extent than to crypt preparations. Rotavirus binding activity was abolished by treatment of membrane preparations with protease. Analysis by glycolytic digestion of BBM with N- and O-glyconases revealed evidence for both N- and O-linked glycosylation of the rotavirus binding protein. Also neuraminidase digestion showed that O-linked sialic acid residues were required for virus binding. Monoclonal antibodies which immunoprecipitate the 300-kDa viral binding glycoprotein react with the apical surface of suckling but not adult enterocytes by Western blot. Baculovirus-expressed vp4, the rotavirus outer capsid spike protein, bound to the 300- and 330-kDa proteins and competed with rotavirus particles for binding sites. The ability of rotavirus to bind via vp4 to large BBM glycoproteins correlates with in vivo rotavirus cell tropism and host range restriction. Specific host cell receptor expression may be important in rotavirus pathogenesis.

Animals↗

An efficient virus concentration method and RT-nested PCR for detection of rotaviruses in environmental water samples.

Water samples were concentrated by the modified adsorption-elution technique followed by speedVac reconcentration of the filter eluates. Reverse transcriptase-nested polymerase chain reaction (RT-nested PCR) was used to detect rotavirus RNA in concentrates of the water. The detection limit of the rotavirus determined by RT-nested PCR alone was about 1.67 plaque forming units (PFU) per RT-PCR assay and that by RT-nested PCR combined with concentration from 1l seeded tap water sample was 1.46 plaque forming units per assay. Water samples were collected from various sources, concentrated, and determined rotavirus RNA. Of 120 water samples, rotavirus RNA was detected in 20 samples (16.7%); 2/10 (20%) of the river samples, 8/30 (26.7%) of the canal samples, and 10/40 (25%) of the sewage samples but was not found in any tap water samples (0/40). Only three water samples were positive for rotavirus antigen determined using an enzyme-linked immunosorbent assay (ELISA). Alignment analysis of the sequenced PCR product (346-bp fragment) was performed in eight rotavirus-positive samples using the rotavirus sequence deposited in the GenBank. All samples gave the correct VP7 sequence. Results of analysis showed two samples similar to human rotavirus (97-98%), five similar to rotavirus G9 sequence (94-99%), and one sample similar to animal rotavirus (97%). PCR inhibitors were not observed in any concentrated water samples. In all 20 (of 120) samples where rotaviruses were found, fecal coliforms including Escherichia coli were also found, but of the samples testing negative for rotaviruses, 76 were fecal coliforms positive and 69 were E. coli positive. The combination of the virus concentration method and RT-nested PCR described below made it possible to effectively detect rotaviruses in environmental water samples.

Reverse Transcriptase Polymerase Chain Reaction↗

Epidemiologic and clinical characteristics of rotavirus disease during five years of surveillance in Venezuela.

BACKGROUND: To effectively introduce a rotavirus vaccine in developing countries, it is necessary to estimate the burden of rotavirus disease. Therefore we examined the epidemiologic and clinical features of rotavirus diarrhea in children younger than 5 years of age in Carabobo State and extrapolated these results to the rest of Venezuela. METHODS: From January 1, 1998 to December 31, 2002, we conducted surveillance for rotavirus diarrhea in all children younger than 5 years of age at the Ciudad Hospitalaria Dr Enrique Tejera, in Valencia (Carabobo). RESULTS: Rotavirus is the major cause of diarrhea in children younger than 5 years of age in Venezuela, accounting for one-fourth (23%) of all episodes of diarrhea requiring medical treatment and one-third (33%) of those requiring hospitalization. Rotavirus diarrhea was responsible for 3% of all hospitalizations and 2% of all medical visits. In Valencia, rotavirus had a marked seasonal peak during the dry and cold months of the year. Rotavirus was most frequent in children 3-23 months of age, and 61% of the cases occurred by the age of 1 year. In addition, rotavirus diarrhea was more severe in younger children. Overall, by the age of 5 years, 1 child in 72 will be hospitalized and 1 in 24 will visit the clinic for rotavirus disease. In Venezuela, we estimated that each year, 118,000 children experience rotavirus illness requiring medical care and 39,000 children require hospitalization. CONCLUSIONS: This study confirms the significant impact of rotavirus disease in Venezuela. Rotavirus vaccines currently in development could diminish the morbidity associated with this common cause of childhood diarrheal disease.

Chi-Square Distribution↗

Acute gastroenteritis in children attending day-care centres with special reference to rotavirus infections. II. Clinical manifestations.

In a prospective study of a cohort of 214 children (aged 6 months-7 years) attending day-care centres, a total of 197 episodes of acute gastroenteritis (GE) occurred in 109 children (i.e. 51% of the participants) during a 12-month observation period. Rotavirus, pathogenic bacteria and Giardia lamblia caused GE in 24%, 6% and 2% of the cases, respectively. The aetiology of the remaining 68% was not discovered. Generally, the symptoms of GE were light and only two episodes led to hospitalization. Thirty-two rotavirus infections were asymptomatic. Two rotavirus GE reinfections occurred. They showed less severe symptoms than the primary infections. The older children (greater than 1.5 years) with rotavirus GE had lighter symptoms than the younger ones (less than or equal to 1.5 years). Compared with children with non-rotavirus GE, those with rotavirus GE showed the following clinical features: (1) Age between 6 months and 2 years. (2) Occurrence of rotavirus GE almost exclusively during the rotavirus season, i.e. January to April (winter). (3) High frequency of vomiting, the onset of which often preceded that of diarrhoea. However, these signs did not form a safe basis for the clinical diagnosis of rotavirus GE. One or more upper respiratory manifestations (URM) were observed in 39% of the children with rotavirus GE and in 36% of those with non-rotavirus GE. The occurrence of URM was age-related being highest in children less than 2 years. Consequently, the existence of a rotavirus syndrome is questioned. It is argued that URM in children with rotavirus GE may be due to a co-infection of the upper respiratory tract by a different micro-organism.

Acute Disease↗

Characterization of group C rotaviruses associated with diarrhea outbreaks in feeder pigs.

Feces and serum specimens were collected from three farms in Michigan on which approximately 50-lb (8- to 9-week-old) pigs experienced diarrhea just after placement into all-in-all-out finishing barns. The clinical signs (profuse watery diarrhea lasting about 2 weeks and no vomiting) were similar on all farms, and the morbidity rate was high (ranging from 60 to 80%) but without mortality. Eleven diarrheic fecal samples from the farms were tested for group A and C rotaviruses by immune electron microscopy (IEM) and various assays. IEM indicated that the fecal samples reacted only with antiserum against group C rotaviruses, and polyacrylamide gel electrophoresis indicated that the samples had characteristic genomic electropherotypes for group C rotavirus. Group C rotavirus was detected by cell culture immunofluorescence (CCIF) tests in nine fecal samples, but no group A rotavirus was detected by enzyme-linked immunosorbent assay or CCIF. By reverse transcription (RT)-PCR, all 11 fecal samples were positive for group C rotaviruses, with only 2 samples positive for group A rotaviruses. However, a second amplification of RT-PCR products using nested primers detected group A rotaviruses in all samples. Analysis of nucleotide and deduced amino acid sequences of the RT-PCR product (partial-length VP7) of the group C rotavirus showed 87.2 to 91% nucleotide identity and 92.6 to 95.9% amino acid identity among two strong samples from the different farms and the Cowden strain of porcine group C rotavirus. All nine convalescent-phase serum samples tested had neutralizing antibodies to the Cowden strain, and the majority of them had neutralizing antibody against group A rotaviruses (OSU or/and Gottfried strains) by fluorescent focus neutralization tests. Although group C rotaviruses have been reported as a cause of sporadic diarrhea in suckling or weanling pigs, to our knowledge, this is the first report of epidemic diarrhea outbreaks associated with group C rotavirus in older pigs.

Animals↗

Rotavirus disease and its prevention.

PURPOSE OF REVIEW: Rotavirus infection is the foremost cause of severe gastroenteritis of young children worldwide. Efforts to develop safe and effective vaccines resulted in licensure of the first live oral vaccine, tetravalent, rhesus-based rotavirus vaccine (RRV-TV), which was incorporated into the US immunization schedule in 1998. Less than 1 year later, however, the vaccine was withdrawn when reports of cases of intussusception were linked to recent vaccination. This setback created significant hurdles as well as new opportunities for the development of the next generation of rotavirus vaccines. This review focuses on new information related to the clinical presentation and pathogenesis of rotavirus infection, the associated global disease burden, and the ongoing efforts to develop and introduce the next generation of rotavirus vaccines for widespread use. RECENT FINDINGS: Recent studies have confirmed that rotavirus infection is not confined only to the gut but can have extraintestinal manifestations, including viremia. Estimates of the global disease burden of rotavirus diarrhea have been refined and suggest that mortality has not declined, and that among hospitalized cases of diarrhea, the fraction associated with rotavirus has increased in many countries. In the United States, the estimated number of hospitalizations attributed to rotavirus has increased. Debate continues about the magnitude of the attributable risk of the association between RRV-TV and intussusception. Several new rotavirus vaccines are in late stages of development. One vaccine was licensed in Mexico in 2004 and a second has completed clinical trials in the United States and Europe and may be licensed within 2 to 3 years. SUMMARY: The tremendous burden of rotavirus diarrhea among children all over the world continues to drive the remarkable pace of vaccine development and the variety of approaches to creating rotavirus vaccines.

Child↗

Virus diversity and an outbreak of group C rotavirus among infants and children with diarrhea in Maizuru city, Japan during 2002-2003.

A total of 236 fecal specimens collected from infants and children with gastroenteritis in Maizuru city, Japan from July 2002 to June 2003, were tested for the presence of rotaviruses, noroviruses, sapoviruses, astroviruses, and adenoviruses by RT-PCR, PAGE, RPHA, and latex agglutination methods. Among diarrheal viruses detected, group A rotavirus was the most prevalent (32.2%; 76 of 236) followed by norovirus GII (21.2%; 50 of 236), group C rotavirus (10.2%; 24 of 236), adenovirus (3.8%; 9 of 236), sapovirus (2.5%; 6 of 236), astrovirus (1.3%; 3 of 236), and norovirus GI (0.8%; 2 of 236), respectively. It is noteworthy that group C rotavirus infection was apparently confined only within the period of 5 months (December 2002 through April 2003). This pattern of infection implied that the outbreak of group C rotavirus in these patients, which was the first outbreak of gastroenteritis attributed to group C rotavirus in Maizuru city. Moreover, about half (12 of 24) of group C rotavirus infected cases were confined to infants and young children less than 3 years old. Another interesting feature of the study was the demonstration of the mixed infections with group C rotavirus and group A rotavirus, as well as group C rotavirus and norovirus GII in 20.8% (5 of 24) and 8.3% (2 of 24), respectively. This is the first report of gastroenteritis associated with the mixed infections with group C rotavirus and other viral enteropathogens such as norovirus. The results indicate that group C rotavirus could infect not only older children and adults but also infants and young children under 3 years old.

Adolescent↗

Prophylaxis of rotavirus gastroenteritis using immunoglobulin.

Oral inoculation of the human group A rotavirus MO strain (G serotype 3) into 5-day-old BALB/c mice causes gastroenteritis characterized by diarrhea. Using this small animal model, passive protection of suckling mice against human rotavirus infection was achieved with the use of immunoglobulin (IgY) from the yolks of eggs of rotavirus-immunized hens. When IgY against the rotavirus strain homotypic with the challenge virus (MO strain) was administered to mice, complete protection was achieved. After immunizing 8-month old pregnant Holstein cows with human rotavirus MO strain, colostrum containing neutralizing antibody to four different G serotypes of human rotavirus, designated Rota colostrum, was obtained. Rota colostrum completely protected suckling mice against rotavirus infection, and purified IgG obtained from Rota colostrum protected against infection with the homologous virus. After randomly grouping 20 infants from a baby care center, 10 infants received 20 ml of Rota colostrum for 2 weeks and 10 control infants received none. Rotavirus-associated diarrhea developed in 7 of the 10 infants in the control group. None of the three infants in the group daily receiving the Rota colostrum had such symptoms, and one of three infants in the group receiving treatment, every other day developed rotavirus-induced diarrhea. Oral administration of Rota colostrum seems to be an effective and safe means of preventing diarrhea caused by human rotavirus infection. Recently, the immunized cows were boosted by reinjection of 4 serotypes of human rotavirus into a superficial cervical lymph node two weeks after delivery, resulting in mass production of cow's milk containing a high-titered antibody to human rotavirus. Therefore, the hyperimmune cow's milk is a candidate for a "physiologically functional food" in Japan.

Animals↗

Rotavirus and not age determines gastroenteritis severity in children: a hospital-based study.

BACKGROUND: The severity of childhood gastroenteritis is generally believed to be age-related rather than aetiology-related. Rotavirus-induced gastroenteritis is more severe than gastroenteritis caused by other enteric pathogens and is also age-related. We thus addressed the question of whether the increased severity of rotavirus-induced gastroenteritis is related to age or to features intrinsic to the agent. STUDY DESIGN: In this multicentre, hospital-based, prospective survey, we evaluated the severity of diarrhoea in rotavirus-positive and rotavirus-negative children up to 4 years of age. Severity was assessed with a score in four groups of age-matched children. RESULTS: Rotavirus was detected in 381 of 911 children. Disease severity was evaluated in 589 cases for which clinical data were complete. The rotavirus-positive and rotavirus-negative groups differed with regards to diarrhoea duration, hospital stay, degree of dehydration and the number of episodes of vomiting. Gastroenteritis was more severe in rotavirus-positive than in rotavirus-negative children. In contrast, none of the main severity parameters differed in the four age groups, irrespective of the presence of rotavirus. CONCLUSIONS: These data provide the evidence that aetiology and not age determines diarrhoeal severity. The demonstration that diarrhoea was more severe in rotavirus-positive children supports the need for a rotavirus vaccine and for studies that address the duration of vaccine protection.

Age Distribution↗

Rotavirus vaccines and the prevention of hospital-acquired diarrhea in children.

Rotavirus, the major cause of severe acute dehydrating gastroenteritis in children less than 5 years of age, is responsible for an estimated 20-50% of all hospitalizations for diarrhea and approximately 440,000 deaths annually, primarily in the developing world. Rotavirus vaccines are considered the most promising means for disease prevention. While the prime rationale for developing rotavirus vaccines has been the enormous burden of rotavirus infection leading to severe and fatal disease, a secondary benefit may be the prevention of nosocomial rotavirus diarrhea. We have reviewed the burden of intra-hospital-acquired rotavirus infections from several countries and found that in the United States alone, as many as 25% of rotavirus hospitalizations or approximately 16,000-18,000 hospitalizations each year might be due to rotavirus infections acquired within hospitals. To countries with low rotavirus-associated mortality, prevention of these infections and the resulting economic savings therefore represent an important secondary goal. Several rotavirus vaccines are in development, and two candidates are currently being tested in large-scale safety and efficacy trials. Development of safe and effective rotavirus vaccines will protect children worldwide against the severe consequences of rotavirus infections including prolonged hospitalizations for nosocomially acquired infections.

Child, Preschool↗

Molecular and immunological methods to detect rotavirus in formalin-fixed tissue.

In 1999, a tetravalent rhesus-based rotavirus vaccine was withdrawn from the market after reports of intussusception cases among vaccinated infants. Methods to detect rotavirus in formalin-fixed pathology specimens from such patients will be important in examining the possible associations between the vaccine and intussusception, in investigating fatalities caused by natural rotavirus infection, and in furthering our understanding of the pathogenesis of rotavirus disease. Three different methods, reverse transcription-polymerase chain reaction (RT-PCR), immunohistochemistry (IHC), and in situ hybridization (ISH), were developed to detect rotavirus in infected cell lines that were fixed in formalin and embedded in paraffin. Using specific primer pairs to identify the VP4 gene with a one-step RT-PCR method, we detected simian rotavirus strains RRV and YK-1 in the liver of an RRV-infected SCID mouse and in the small intestine of an YK-1 infected macaque, respectively. Using a two-step indirect immunoalkaline phosphatase technique, we found RRV antigens in the liver of an infected SCID mouse with a rabbit polyclonal anti-group A rotavirus antibody and a murine monoclonal anti-rotavirus VP2 antibody. Using riboprobes designed to detect RRV genes, VP4 and NSP4, we obtained a positive hybridization signal in the same area of the infected SCID mouse liver as the area in which rotavirus antigens were localized. These techniques should prove valuable to detect rotavirus antigens and nucleic acids in tissues from patients infected naturally with rotavirus or with intussususception associated with rotavirus vaccine.

Animals↗

Group B rotaviruses similar to strain CAL-1, have been circulating in Western India since 1993.

Generally, group A rotaviruses are the most common cause of paediatric diarrhoea. However, group B rotavirus, adult diarrhoea rotavirus (ADRV), was found to be involved in epidemics of severe gastroenteritis in several areas of China during 1982-1983 and had resulted in more than one million cases among adults as well as older children. Human group B rotavirus has been rarely reported outside China, but has been detected first from five adults with diarrhoea in Kolkata, India during 1997-1998 (strain CAL-1). During epidemiological studies at the National Institute of Virology (NIV) on hospitalized diarrhoea patients at Pune, India, faecal specimens from patients of >5 years age, which were negative for group A rotavirus by ELISA were tested by polyacrylamide gel electrophoresis (PAGE). We detected rotavirus RNA migration patterns similar to that of group B rotavirus in three faecal specimens from adults, two from the specimens collected in 1993 and one in 1998 from sporadic diarrhoea cases. RT-PCR was carried out using primers derived from gene 8 which codes for the NS2 protein, followed by nested PCR, which confirmed the presence of group B rotavirus in all three specimens. The sequences of the PCR products of NIV specimens were compared with that of CAL-1, ADRV and IDIR (infectious diarrhoea of infant rat) belonging to group B rotaviruses. The sequence analysis of the PCR products showed the highest identity with CAL-1, which was reported from Kolkata, India during 1997--1998. The finding suggests that human group B rotaviruses have been circulating in Pune. India, since 1993. This emerging virus may lead to more severe disease among adults in India. There is a need for surveillance of group B rotavirus infections, especially in adult diarrhoea cases and seroepidemiological studies on group B rotavirus are required among humans and animals of Western Maharashtra, India.

Adult↗

Comparison of atypical rotaviruses from calves, piglets, lambs and man.

Some rotaviruses from calves, piglets, and lambs were detected by electron microscopic examination of faeces but not by an enzyme-linked immunosorbent assay which relies on detection of group antigen. On further examination by polyacrylamide gel electrophoresis, these viruses had 11 segments of dsRNA, as had typical rotaviruses, but arranged in atypical patterns. From humans, three rotaviruses with atypical electrophoretypes were also detected. Gnotobiotic animals were infected with atypical calf, piglet and lamb rotaviruses, and used to provide antigen and antiserum for an immunofluorescent comparison of these rotaviruses with conventional rotaviruses and other previously described atypical rotaviruses from piglets and chickens. Two atypical rotaviruses from humans failed to infect gnotobiotic piglets. The atypical rotaviruses could be tentatively categorized into two groups serologically distinct from each other and from conventional rotaviruses, and these distinctions were consistent with electrophoretypes . The atypical chicken rotavirus may form a fourth distinct group. These findings are consistent with the hypothesis that rotaviruses belong to at least four separate groups definable by serology and electrophoretype .

Animals↗

Molecular characterization of human group C rotavirus genes 6, 7 and 9.

Genes 6, 7 and 9 of human group C rotavirus 'Bristol' strain, encoding non-structural proteins (NSP) 3, 1 and 2, respectively, were cloned and sequenced. Human group C rotavirus genome segment 6 is 1350 bp and contains a single ORF of 1231 nucleotides (encoding 402 amino acids). Genome segment 7 is 1270 bp and encodes a protein of 394 amino acids and genome segment 9 is 1037 bp and encodes a 312 amino acid protein. The human group C rotavirus genes 6, 7 and 9 showed 78, 67 and 88% sequence identity, respectively, to the corresponding porcine group C rotavirus genes. The derived protein sequences were compared with those of the porcine 'Cowden' group C and mammalian group A rotavirus strains. The human group C rotavirus NSP1 protein sequence is one amino acid longer than the porcine group C equivalent. In common with group A and porcine group C rotaviruses, the human group C rotavirus NSP1 protein has a zinc finger motif. Human group C rotavirus NSP2 has two hydrophobic heptad repeat regions, a basic, RNA-binding domain and a basic, proline-rich region. Human group C rotavirus NSP3 has both single- and double-stranded RNA-binding domains and several hydrophobic heptad repeat regions, one of which forms a leucine zipper. This work completes the molecular characterization of the non-structural proteins of a human group C rotavirus. Phylogenetic analysis of all the non-structural genes of group A, B and C rotaviruses suggests that these viruses have diverged at a constant rate from a common ancestor.

Amino Acid Sequence↗