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Humoral immune response to rotavirus NSP4 enterotoxin in Spanish children.

The rotavirus non-structural protein 4 (NSP4) has been shown to play a crucial role in rotavirus-induced diarrhea, acting as a viral enterotoxin. It has also been demonstrated that antibody to NSP4 can reduce the severity of rotavirus-induced diarrhea in newborn mice. Two recombinant baculoviruses, expressing the NSP4 protein from the SA11 and Wa rotavirus strains, genotypes A and B, respectively, were used to produce and purify these glycoproteins, which were applied as antigen in an enzyme-linked immunosorbent assay (ELISA) to test the specific antibody response to NSP4 in human sera. Serum samples from 30 children convalescing from a rotavirus infection, from 54 healthy children under 5-years-old, and from 49 adults were tested to determine the presence of antibodies to the viral enterotoxin and to rotavirus structural proteins. Seventy percent of the sera from rotavirus-infected children showed an IgG antibody response to either one or both NSP4 proteins used in this study, although the response was weak. However, IgG antibodies towards either one or both NSP4 proteins were only detected in 26% of the non-convalescent healthy children and in only 18% of the adults. No serum IgA antibodies towards NSP4 were found in this study. IgG antibody recognition of the NSP4 protein from the SA11 and Wa rotavirus strains was not always heterotypic.

Adult↗

Role of nitric oxide during rotavirus infection.

The pathophysiological mechanisms behind rotavirus-induced diarrhoea still remain incomplete. Current views suggest that the non-structural protein 4 (NSP4) of rotavirus and the enteric nervous system (ENS) participate in water secretion and diarrhoea. In the present work the role of nitric oxide (NO) in rotavirus infection and disease has been studied in vitro, mice and humans. Incubation of human intestinal epithelial cells (HT-29) with purified NSP4 but not with infectious virus produced NO2/NO3 accumulation in the incubation media. The NSP4-induced release of NO metabolites occurred within the first minutes after the addition of the toxin. Mice infected with murine rotavirus (strain EDIM) accumulated NO2/NO3 in the urine at the onset for diarrhoea. Following rotavirus infection, inducible nitric oxide synthetase (iNOS) mRNA was upregulated in ileum, but not in duodenum or jejunum of newborn pups within 5 days post-infection. A prospective clinical study including 46 children with acute rotavirus infection and age-matched controls concluded that rotavirus infection stimulates NO production during the course of the disease (P < 0.001). These observations identify NO as an important mediator of host responses during rotavirus infection.

Animals↗

Stimulation of local immunity and protection in mice by intramuscular immunization with triple- or double-layered rotavirus particles and QS-21.

Based on studies in animal models, parenteral immunization has become recognized as a potential vaccination strategy against rotavirus. Using an adult mouse model, the effects of the saponin adjuvant QS-21 on protection against murine rotavirus (strain EDIM) infection was determined following two intramuscular (i.m.) immunizations with purified EDIM particles including triple-layered (tl) infectious particles, tl particles inactivated with psoralen/UV, and double-layered (dl) inactivated particles. All three particles stimulated large serum rotavirus IgG responses and small amounts of serum rotavirus IgA, but undetectable stool rotavirus IgA. Inclusion of QS-21 during immunization increased the serum responses approximately 2- to 10-fold and also stimulated low levels of stool rotavirus IgA. Protection based on reduced shedding of rotavirus following EDIM challenge was significant (P < 0.001) with each immunized group and was enhanced (P < 0.001) by inclusion of QS-21 during immunization. Mice immunized with either live or inactivated tl particles and QS-21 were almost fully protected. Furthermore, animals inoculated with dl particles and the adjuvant shed significantly (P = .02) less virus following challenge than mice immunized with inactivated tl particles even though the latter induced measurable titers of neutralizing antibody to EDIM. These results demonstrate significant protection against rotavirus following i.m. immunization with both dl and tl EDIM particles which is consistently enhanced with QS-21.

Adjuvants, Immunologic↗

Group A rotavirus G type prevalence in two regions of Hungary.

Rotaviruses are a major cause of gastroenteritis in children world-wide. Rotaviruses are antigenically complex, with multiple serotypes (G types). The first longitudinal study of group A rotavirus serotype (G type) distribution in Hungary is reported. Neutralizing monoclonal antibodies specific for G1, G2, G3, and G4 were used in an enzyme immunoassay to determine the antigenic variation of group A rotaviruses in two collections of stool specimens assembled from 1984-1992 in Baranya County, southwest Hungary, and from 1988-1992 at the Central Hospital for Infectious Diseases in Budapest. Ninety-two percent of the 1215 virus-positive samples were typed as follows: G1 (81%), G2 (4%), G3 (1%), G4 (5%), or mixed type (1%). G1 was the predominant type during the entire study period with the exception of the 1988/1989 rotavirus season in Baranya County when G4 predominated. Among G1 strains, different electropherotypes were detected with a shift of the predominant G1 electropherotype(s) each 2 to 3 years. G typing from two longitudinal collections established regional differences within Hungary in the prevalence of rotavirus antigenic types among children with rotavirus-associated diarrhea. These are the first longitudinal rotavirus typing results for Hungary and Central Europe.

Antibodies, Monoclonal↗

Evaluation of specificity and effects of monoclonal antibodies submitted to the Eighth Human Leucocyte Differentiation Antigen Workshop on rotavirus-cell attachment and entry.

Rotavirus infection of permissive cells is a multi-step process that requires interaction with several cell surface receptors. Integrins alpha2beta1, alpha4beta1, alphaXbeta2, and alphavbeta3 are involved in the attachment and entry into permissive cells for many rotavirus strains. However, possible roles of known partners of these integrins in this process have not been studied. Here, the specificities of new monoclonal antibodies directed to beta1 and beta2 integrins were determined using integrin-transfected cells. The ability of monoclonal antibodies to integrin partners CD82, CD151, CD321, and CD322 to bind rotavirus-permissive cell lines (MA104, Caco-2, and RD) and K562 cells expressing or lacking alpha4beta1 also was investigated. CD82 and CD151 were expressed on K562, alpha4-K562, and RD cells. CD321-specific antibodies bound K562, alpha4-K562, MA104, and Caco-2 cells. CD322 expression was detected on MA104 but not Caco-2 cells. Antibodies to CD82, CD151, CD321, and CD322 that bound these cells were investigated for their ability to inhibit cellular attachment and entry by rotaviruses. Antibody blockade of these integrin-associated proteins did not affect cell attachment or entry of the integrin-using rhesus rotavirus RRV or porcine rotavirus CRW-8, which uses alpha4beta1 integrin for infection. Antibody blockade of CD322 did not alter cell attachment or infectivity by human rotavirus strain RV-3, so RV-3 infection was independent of CD322. Overall, these studies indicate that CD82, CD151, CD321, and CD322 are unlikely to play a role in rotavirus-cell binding or entry.

Antibodies, Monoclonal↗

Genetic distribution of group A human rotavirus types isolated in Gyunggi province of Korea, 1999-2002.

BACKGROUND: Human rotavirus genotypes G1-G4 and G9 are the major etiological agents of infantile gastroenteritis. G1 was the most prevalent in Korea during the 10-year period prior to 1997. However, between 1998 and 1999, G4 was the predominant type in Korea, as it was in other Asian countries. OBJECTIVES: The circulating pattern and genetic variability of group A human rotavirus in Gyunggi, Korea, 1999-2002, were examined in 189 stool specimens. STUDY DESIGN: Stool samples were collected from children with diarrhea, and group A human rotavirus type was determined using multiplex RT-PCR in those specimens found to be positive for rotavirus by ELISA. Each genotype was sequenced, and phylogenetic analysis was performed on the sequences. RESULT: We found significant variability from year to year in the prevalence of different G and P types of rotavirus. We also found relatively high prevalence rates for types normally considered to be uncommon. Furthermore, we found that the most prevalent combination of G and P types changed from year to year. Although the combination of G and P types changed every year, the sequence of G genotypes showed a high level of similarity (>97%) compared to those of strains from other Asian countries. CONCLUSION: We report the types of rotavirus circulating in Gyunggi province, Korea from 1999 to 2002. This information on rotavirus diversity has important implications for rotavirus vaccine efficacy and future vaccine development.

Antigens, Viral↗

Species-specific but not genotype-specific primary and secondary isotype-specific NSP4 antibody responses in gnotobiotic calves and piglets infected with homologous host bovine (NSP4[A]) or porcine (NSP4[B]) rotavirus.

Using recombinant baculoviruses expressing rotavirus NSP4 [A], [B], [C], and [D] genotypes of bovine, porcine, human, simian, or murine origin, we analyzed serum antibody responses to NSP4s in gnotobiotic calves and piglets infected by the oral/alimentary or intraamniotic route with bovine (NSP4[A]) (Wyatt, R.G., Mebus, C.A., Yolken, R.H., Kalica, A.R., James, H.D., Jr., Kapikian, A.Z., Chanock, R.M., 1979. Rotaviral immunity in gnotobiotic calves: heterologous resistance to human virus induced by bovine virus. Science 203(4380), 548-550) or porcine (NSP4[B]) (Hoshino, Y., Saif, L.J., Sereno, M.M., Chanock, R.M., Kapikian, A.Z., 1988. Infection immunity of piglets to either VP3 or VP7 outer capsid protein confers resistance to challenge with a virulent rotavirus bearing the corresponding antigen. J. Virol. 62(3), 744-748) rotaviruses. Following primary infection and challenge with virulent rotaviruses, the animals developed higher or significantly higher antibody titers to homologous host homotypic NSP4s than to heterologous host homotypic or heterologous host heterotypic NSP4s, indicating that antibody responses were species specific rather than genotype specific. Antibody responses to NSP4s corresponded closely with the phylogenetic relationships of NSP4s within a species-specific region of amino acids (aa) 131-141. In contrast, NSP4 genotypes determined by amino acid full-length sequence identity predicted poorly their "serotypes". In piglets, antibodies to NSP4 induced by previous oral infection failed to confer protection against challenge from a porcine rotavirus bearing serotypically different VP4 and VP7 but essentially identical NSP4 to the porcine rotavirus in primary infection. Thus, in an approach to immunization with a live oral rotavirus vaccine, the NSP4 protein does not appear to play an important role in protection against rotavirus disease and infection.

Amino Acid Sequence↗

Identification of the novel lapine rotavirus genotype P[22] from an outbreak of enteritis in a Hungarian rabbitry.

Application of improved molecular techniques in the detection and characterization of rotavirus strains has led to the recent description of several new combinations, specificities, and genetic variants of the outer capsid genes, VP7 and VP4. In spite of the enormous diversity of mammalian rotavirus strains, the few lapine rotaviruses characterized to date, appear to carry a narrow range of such antigen combinations; only P[14], G3 and, based on a more recent study, P[22], G3 rotaviruses have proved to be epidemiologically important in rabbits. In the present study, we characterized a lapine group A rotavirus with a super-short electropherotype detected in an outbreak of fatal enteritis in a Hungarian commercial rabbitry. Based on sequence and phylogenetic analysis of the VP7, VP4, and NSP4 genes, our lapine strain is a P[22], G3 rotavirus that carries the NSP4 genotype shared by most lapine rotaviruses. Although the P[22] VP4 specificity has been newly identified, the relatively high sequence variation between our strain and those identified in Italy (89.1-90.4% nucleotide identity; region VP8*) implies that these strains diversified far before they were described for the first time, strongly suggesting that this genotype may have circulated in rabbitries or in nature without prior detection. We conclude that genotype P[22] lapine rotaviruses show a wider geographical dispersal than previously thought, although understanding their true epidemiological significance needs further investigation.

Animal Husbandry↗

Interferon gamma and interleukin 1, but not interferon alfa, inhibit rotavirus entry into human intestinal cell lines.

BACKGROUND & AIMS: Rotavirus, an important agent of gastroenteritis in children, causes diarrhea by infecting differentiated villus enterocytes in the small intestine. The aim of this study was to determine whether cytokines that can be expressed by mucosal cells have an effect on the rotavirus susceptibility of cultured human enterocytes. METHODS: Caco-2 and HT-29 cells were pretreated with various cytokines before challenge with rotavirus. RESULTS: Interleukin (IL)-1, interferon (IFN)-alpha, and IFN-gamma pretreatment led to a dose-dependent resistance to rotavirus infection. Maximum effects occurred after 72 hours of pretreatment, whereas no detectable inhibition occurred with <12 hours of pretreatment. Liposomal transfection of single-shelled and double-shelled rotavirus particles bypassed the block to rotavirus replication in IFN-gamma- and IL-1-treated but not IFN-alpha-treated cells. Binding studies with purified, metabolically labeled rotavirus showed no significant difference among IFN-gamma- and IFN-alpha-treated and control Caco-2 cells. Viral entry into Caco-2 cells was significantly inhibited by IFN-gamma and IL-1 but not IFN-alpha. CONCLUSIONS: IFN-alpha and IFN-gamma induce rotavirus resistance by different mechanisms, suggesting that cytokines play a role in host defense against viral agents by changing the phenotype of intestinal epithelial cells.

Antiviral Agents↗

Molecular biology of rotavirus cell entry.

Rotaviruses, the leading cause of severe dehydrating diarrhea in infants and young children worldwide, are non-enveloped viruses formed by three concentric layers of protein that enclose a genome of double-stranded RNA. The entry of rotaviruses into epithelial cells appears to be a multistep process during which at least three contacts between the virus and cell receptors occur. Different rotavirus strains display different requirements to infect cells. Some strains depend on the presence of sialic acid on the cell surface; however, interaction with a sialic acid-containing receptor does not seem to be essential, because variants that no longer need sialic acid to infect the cells can be isolated from sialic acid-dependent strains. Comparative characterization of the sialic acid-dependent rotavirus strain RRV, its neuraminidase-resistant variant nar3, and the human rotavirus strain Wa have allowed to show that alpha2beta1 integrin is used by nar3 as its primary cell attachment site, and by RRV in a second interaction subsequent to its initial contact with a sialic acid-containing cell receptor. These first two interactions are mediated by the virus spike protein VP4. After attaching to the cell, all three strains interact with integrin alphaVbeta3 and protein hsc70, interactions perhaps important for the virus to penetrate into the cell's interior. The cell molecules proposed to serve as rotavirus receptors have been found associated with cholesterol and glycosphingolipid-enriched lipid microdomains, and disorganization of these domains greatly inhibits rotavirus infectivity. We propose that the functional rotavirus receptor is a complex of several cell molecules most likely immersed in plasma membrane lipid microdomains.

Capsid Proteins↗

Rotavirus infection in adults.

Rotavirus has been recognised for 30 years as the most common cause of infectious gastroenteritis in infants and young children. By contrast, the role of rotavirus as a pathogen in adults has long been underappreciated. Spread by faecal-oral transmission, rotavirus infection in adults typically manifests with nausea, malaise, headache, abdominal cramping, diarrhoea, and fever. Infection can also be symptomless. Rotavirus infection in immunocompromised adults can have a variable course from symptomless to severe and sustained infection. Common epidemiological settings for rotavirus infection among adults include endemic disease, epidemic outbreak, travel-related infection, and disease resulting from child-to-adult transmission. Limited diagnostic and therapeutic alternatives are available for adults with suspected rotavirus infection. Because symptoms are generally self-limiting, supportive care is the rule. Clinicians caring for adults with gastroenteritis should consider rotavirus in the differential diagnosis. In this review we intend to familiarise clinicians who primarily provide care for adult patients with the salient features of rotavirus pathophysiology, clinical presentation, epidemiology, treatment, and prevention.

Adult↗

Immunological aspects of interaction between rotavirus and the intestine in infancy.

Rotaviruses are important pathogens causing severe diarrhoea in human infants and young animals. Available information on the pathogenic mechanisms of and the immune response to rotaviruses is reviewed here. Studies in our laboratory using the suckling mouse model have focused on elucidating the nature of interaction between the virus and the gut, and on the importance of T and B cell mediated immunity in protection and recovery from the disease. Our data suggest that the age dependence of mouse rotavirus (MRV) infection is related to the presence of virus-specific receptors on the enterocytes. The uptake of rotavirus antigens appears to be limited to the epithelium associated with Peyer's patches. The antigen is transported to local and regional lymph nodes. Recent studies have indicated that rotavirus infection also increases the uptake of other macromolecules in the intestine. Rotavirus-specific mucosal IgA response seems to be related to the location and magnitude of MRV antigen in the lymph follicles in different segments of the small intestine. Studies in mice with different types of immunodeficiency suggest that a specific immune response is required for complete resolution of virus infection. Several parameters of immunity to rotavirus infection have been examined and, similar to other reports, local immunity in the intestine appears to have the most important role in protection. It also has been observed that nutritional factors may be important in modifying disease. However, there are still many questions to be answered concerning the role of immunity in mediating the pathogenesis of rotavirus infection.

Animals↗

Detection and characterization of human rotavirus among children with diarrhoea in Botswana.

This study reports the detection, for the first time, of human rotavirus in stools of children and the molecular characterization of isolated circulating strains in Botswana. We collected 249 stool samples between 1999 and 2001 from children with diarrhoea in three health districts of Botswana and examined them for the presence of rotavirus antigens and particles. Group A rotavirus antigen was detected in 43 of 249 (17%) of the samples tested by enzyme-linked immunosorbent assay. Of the 43 children shedding rotaviruses, 37 (86%) were infants < or =2 years of age. The presence of rotavirus particles was also confirmed by direct electron microscopy. The characteristic 11 segments of the double-stranded RNA mobility pattern of rotavirus were demonstrated by polyacrylamide electrophoresis in 20 of 43 (47%) of the rotavirus-positive samples. The predominant electrophoretic pattern detected was the long (L) electrophoretype 14 of 20 (70%) followed by the short (S) electrophoretype five of 20 (25%). One strain had a mixed (L/S) pattern. Of the 26 samples subjected to subgrouping by enzyme immuno assay, eight were typed as subgroup-II specific and seven were subgroup I. The predominant VP7 genotypes detected were G1 (59%). Two mixed strains of G1 + G3 (5%) and G1 + G2 (5%) were also detected. VP4 genotypes in circulation were: P[4] (5%), P[6] (33%) and P[8] (33%). Mixed P-types P[4 + 6] (5%) and P[6 + 8] (18%) were also detected. Rotavirus strains G1 P[8] and GI P[6 + 8] were the most common cause of diarrhoea in our study area.

Age Distribution↗

Nested reverse transcriptase-polymerase chain reaction for the detection of group A rotaviruses.

Rotaviruses are important pathogens associated with diarrhoeal diseases in almost all species of mammals. In the present study, a nested reverse transcriptase-polymerase chain reaction (RT-PCR) for the detection of group A rotaviruses was developed, which is based on a target region in gene segment 6. Rotavirus strains of human, bovine, porcine, canine, feline, equine, and ovine origin were examined. Furthermore several faecal specimens, in which rotavirus had already been detected using other methods than PCR, were included in the study. A nested RT-PCR product was formed with all strains and faecal samples tested. The detection limit for virus-containing cell culture supernatant was 3 x 10(-2) [50% tissue culture infective dose (TCID50)] by RT-PCR and 3 x 10(-3) TCID50) by nested amplification. In order to examine the influence of the sample matrix on sensitivity, a rotavirus-negative faecal specimen was spiked with virus-containing cell culture suspension of the porcine rotavirus OSU. The detection limit of the present PCR procedure was approximately 1.6 x 10(2) TCID50 per g faeces and could be increased by one order of magnitude using nested PCR. The present method for detection and identification of group A rotaviruses represents a powerful diagnostic tool and was shown to be applicable to rotaviruses of different origin, including human sources.

Animals↗

Incidence and genetic diversity of group C rotavirus among adults.

Fecal samples from a 1-year prospective study were investigated to establish the role of group C rotavirus infections in acute diarrhea in Swedish adults (>15 years old). Rotaviruses were found in samples from 3% of the patients, and, in 35% of these, group C rotavirus was detected. Clinical symptoms of group C rotavirus infection were generally milder than those of group A rotavirus infection. Gene 8 (vp7) from 12 group C isolates, including strains from the prospective study, a military outbreak, and a sporadic case, was sequenced. The gene was found to be extremely conserved, with identities of 99.1%-100% at the amino acid level. This study has systematically investigated the prevalence and genetic diversity of group C rotavirus in adults. The data confirm the extreme sequence conservation within human group C rotavirus strains and suggest that symptomatic group C rotavirus infections occur more frequently in adults than has been previously recognized.

Adult↗

The pathology of rotavirus-associated deaths, using new molecular diagnostics.

Rotavirus, the most common cause of severe, dehydrating gastroenteritis among children worldwide, annually causes approximately 500,000 deaths among children aged <5 years. The primary site of rotavirus infection is the small intestine. Pathologic investigations of patients who died of rotavirus infection are limited to data from a few reported autopsies, and dehydration with electrolyte imbalance is believed to be the major cause of death. Several recent reports suggest that children who died during a rotavirus illness were viremic before death, because rotavirus was detected at several extraintestinal sites. We report 3 rotavirus-associated deaths among children, 2 of whom had evidence of rotavirus genome in extraintestinal tissues detected by use of novel molecular diagnostic methods. The part played by rotavirus in fatal cases is unclear and requires additional investigation of diarrhea-associated deaths, because a better understanding might alter the approach to treatment and the need for antiviral therapy.

Brain Stem↗

Sentinel hospital surveillance for rotavirus diarrhea in Taiwan, 2001-2003.

We examined the epidemiological profile of rotavirus infection among children hospitalized for diarrhea in Taiwan, to assess the burden of this disease. From 1 April 2001 through 31 March 2003, children <5 years old with gastroenteritis admitted to 4 sentinel hospitals were enrolled in a surveillance study and had stool specimens tested for the presence of rotavirus, enteric adenovirus, and the bacterial pathogens for which routine screening is performed. For 52% of patients, a recognized enteric pathogen was identified, including rotavirus (43% of patients), bacteria (11%), enteric adenovirus (2.5%), and a mixture of pathogens (3.9%). Rotavirus was detected year-round, but great month-to-month variability made it difficult to identify a distinct seasonal pattern. Rotavirus disease was most common among children 7-23 months old, but the rate of rotavirus detection varied little between the youngest and oldest age groups. The novel strain P[8]G9 was detected most commonly (37% of strains), followed by strains P[8]G1 (31%), P[4]G2 (10%), P[8]G3 (9.3%), and P[8]G4 (3.7%). Rotavirus infection is the most important cause of diarrhea among hospitalized children in Taiwan, and a rotavirus vaccination program for young children might significantly reduce this problem.

Diarrhea↗

Projected cost-effectiveness of rotavirus vaccination for children in Asia.

BACKGROUND: New rotavirus vaccines may soon be licensed, and decisions regarding implementation of their use will likely be based on the health and economic benefits of vaccination. METHODS: We estimated the benefits and cost-effectiveness of rotavirus vaccination in Asia by using published estimates of rotavirus disease incidence, health care expenditures, vaccine coverage rates, and vaccine efficacy. RESULTS: Without a rotavirus vaccination program, it is estimated that 171,000 Asian children will die of rotavirus diarrhea, 1.9 million will be hospitalized, and 13.5 million will require an outpatient visit by the time the Asian birth cohort reaches 5 years of age. The medical costs associated with these events are approximately 191 million US dollars; however, the total burden would be higher with the inclusion of such societal costs as lost productivity. A universal rotavirus vaccination program could avert approximately 109,000 deaths, 1.4 million hospitalizations, and 7.7 million outpatient visits among these children. CONCLUSIONS: A rotavirus vaccine could be cost-effective, depending on the income level of the country, the price of the vaccine, and the cost-effectiveness standard that is used. Decisions regarding implementation of vaccine use should be based not only on whether the intervention provides a cost savings but, also, on the value of preventing rotavirus disease-associated morbidity and mortality, particularly in countries with a low income level (according to 2004 World Bank criteria for the classification of countries into income groups on the basis of per capita gross national income) where the disease burden is great.

Asia↗