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PubMed1998

Role of human-milk lactadherin in protection against symptomatic rotavirus infection.

BACKGROUND: Human milk contains a 46 kDa mucin-associated glycoprotein, lactadherin, which binds specifically to rotavirus and inhibits its replication. This study tested the hypothesis that lactadherin protects against symptoms of rotavirus infection. METHODS: 200 infants in Mexico City were recruited at birth and monitored by regular stool EIA for rotavirus, serology, and recording of feeding and stool patterns. Milk samples were obtained from the mothers weekly until 4 weeks post partum then monthly. The sample taken immediately before an infant's episode of rotavirus infection was assayed for lactadherin, butyrophilin, mucin, and secretory IgA. An infection was defined as symptomatic if diarrhoea occurred in the 5 days before or after detection of the virus. FINDINGS: 31 infants developed rotavirus infection; 15 were symptomatic and 16 had no symptoms. The median concentration of lactadherin in the milk samples (obtained 4-41 days [median 13] before the infection) was 48.4 (range 5.6-180) microg/mL in the asymptomatic group and 29-2 (6.2-103-4) microg/mL in the symptomatic group. Although these medians did not differ significantly, in logistic regression analysis adjusted for age at infection and secretory IgA concentration there was a significant difference between the groups (p=0O01). No association between symptom status and concentrations of butyrophilin, mucin, or secretory IgA was found. INTERPRETATION: Protection against rotavirus by human milk is associated with the glycoprotein lactadherin. This association is independent of products of the secretory immune system.

Adult↗
PubMed1997

Protective immunity induced by rotavirus DNA vaccines.

It is estimated that Group A rotavirus diarrhea causes as many as one million deaths per year in children worldwide, and effective vaccines will be essential for their control. Plasmid DNA vaccines encoding murine rotaviral proteins VP4, VP6, or VP7 were tested in adult BALB/c mice for their ability to induce immune responses and provide protection against rotavirus challenge. The vaccines were administered by inoculation into cells of the epidermis with an Accell gene gun. (Auragen, Inc., Middleton, WI, USA). Each vaccine elicited rotavirus-specific serum antibodies as measured by ELISA. Virus neutralizing antibodies were detected in mice receiving plasmid DNAs encoding for outer capsid proteins VP4 and VP7, but not for VP6, an inner capsid protein, and all of the vaccines generated virus-specific CTL responses. Each vaccine was effective in protecting mice against infection after homotypic rotavirus (100 ID50) challenge, showing reductions (P < 0.0002) in viral excretion measured over a 9 day period. Increased rotavirus-specific intestinal IgA antibodies were seen in vaccinated mice after rotavirus challenge, particularly in mice that received the VP6 DNA vaccine. This suggests that intracellular IgA-mediated neutralization may be involved in protective immunity induced by the VP6 DNA vaccine, and may represent a new mechanism for protection by DNA vaccines.

Animals↗
PubMed2000

The stability of porcine rotavirus in feces.

Rotaviruses are known as major causal agents of diarrhea in humans and animals. They affect young animals in intensive rearing and cause great economic losses. This study evaluated the infectivity of porcine rotavirus maintained for 32 months at approximately 10 degrees C in the original stool specimens. Thirty stool specimens of 1-4-week-old piglets from breeding farms located in the southwest of the State of Parana were selected for this study. They were randomly chosen from stool samples positive for rotavirus RNA by polyacrylamide gel electrophoresis (PAGE) at the time of collection. The thirty stool samples maintained for 32 months were re-tested by PAGE and 11 out of 30 were still positive showing physical integrity of the eleven segments of viral RNA. In order to demonstrate the maintenance of viral infectivity processed fecal homogenates were inoculated in MA-104 cell cultures. After an average of three blind passages 5 out of 11 samples demonstrated cytopathic effect similar to that of a simian rotavirus (SA-11) used as positive control. To confirm these findings an immunofluorescence test was performed and typical cytoplasmatic granular fluorescence was observed. Electron microscopy of stool samples showed that most of the virus particles were single-shelled and some were found to be in advanced state of degradation. The viral nucleic acid extracted from six fecal specimens out of those that showed physical integrity of rotavirus RNA by PAGE were also amplified when submitted to RT-PCR demonstrating stability of viral RNA. We therefore concluded that porcine rotavirus infectivity is maintained for a long period of time in stool specimens at low temperature.

Animals↗
PubMed2001

Evaluation of two current generation enzyme immunoassays and an improved isolation-based assay for the rapid detection and isolation of rotavirus from stool.

BACKGROUND: Rapid and accurate rotavirus testing is important in decisions involving patient care and management. Quality assurance testing needs to be periodically performed, especially among widely used assays having a direct impact on patient care. OBJECTIVES: To evaluate the current generation Kallestad Pathfinder Direct antigen Detection system (PTH), and the widely used Rotaclone(R) Rotavirus EIA Diagnostic Kit (RTC), in comparison with an improved cell culture amplification-antigen detection (CCA-Ag) isolation-based assay. STUDY DESIGN: Two hundred stool specimens (specimen stored at > or =-75 degrees C), which had been previously tested by PTH, were tested by RTC and CCA-Ag. Discordant specimens were retested by PTH, blocking assay, polyacrylamide gel electrophoresis (PAGE), and/or electron microscopy (EM). RESULTS: Among 200 stool specimens, 197 were in accord by PTH, RTC and CCA-Ag. The sensitivity, specificity, positive and negative predictive values for RTC, PTH and CCA-Ag were, 100, 99, 99, 100, 100, 99, 99, 100; and 98, 100, 100, 98%, respectively. Among five initially discordant specimens, two required a period of 10 days to affect isolation. A non-cultivatable (CCA-Ag negative) but true positive specimen, was identified as rotavirus group A serotype G2 by RT-PCR. Four true positive but discordant specimens were blocking assay negative using one or both EIA kits. CONCLUSIONS: PTH and RTC are excellent rotavirus detection system. However, PTH is more expensive (ca. $3.50 vs. $2.00 per test), mandates a slightly longer turn-around time (ca. 1 vs. 1.5 h), and necessitates slightly more hands-on manipulative/preparative steps. Blocking assay was not a reliable confirmatory test for the resolution of specimen discordancy. A combination of CCA-Ag, PAGE, EM, and/or perhaps RT-PCR, is recommended as an appropriate test panel for the resolution of discordant results during assay evaluation. The newly modified and simplified 48-h rotavirus isolation-based assay may serve as a base line methodology in laboratory evalaution studies, as a laboratory support methodology during drug/vaccine efficacy trials, or for the testing of sources (e.g., biopsy/autopsy tissues) not approved for assay by commercial rotavirus kits.

Antigens, Viral↗
PubMed2003

Molecular characterization of rotavirus strains from children in Toronto, Canada.

BACKGROUND: Rotaviruses are the most common agents of diarrheal illness of infants and young children. Gastroenteritis caused by rotaviruses is also more likely to be associated with severe dehydration compared to other viral gastroenteritis. OBJECTIVES: We determined the G-serotype of rotaviruses circulating in the Metro Toronto-Peel County region, during the 1997-1998 winter. STUDY DESIGN: Stool samples were collected in Metro Toronto-Peel county region from November 1, 1997 to June 30, 1998. Rotavirus presence was demonstrated by electron microscopy and ELISA. A reverse transcription-polymerase chain reaction (RT-PCR) assay for the amplification of the near-complete RHA segment 9 of rotavirus was developed and used to determine the G-serotype by sequencing and phylogenetic analysis. RESULTS: A total of 135 rotavirus isolates were used as templates for RT-PCR. Of these, four could not be amplified and one revealed a mixed infection. The G-serotypes could be unambiguously determined for the other isolates. Of these, 85 were of G-serotype 1, 41 of G2, 1 of G3, 1 of G4, and 2 of G9. CONCLUSION: Our RT-PCR assay enables unambiguous determination of the G-serotype. The overall relative incidence of G-serotypes in Toronto is similar to that of other developed countries. Serotype G9 was present at low levels in Toronto.

Antigens, Viral↗
PubMed2004

Role of rotaviruses in children with acute diarrhea in Tehran, Iran.

BACKGROUND: Rotavirus illness is associated with significant cause of morbidity and is a common cause of hospitalization worldwide. OBJECTIVE: This study was performed to assess the role of rotaviruses in children presenting with acute diarrhea in two main Children's Medical Centers and one general hospital in Tehran. STUDY DESIGN: Stool specimens from 704 children less than 5 years of age suffering from diarrhea were tested for the presence of rotaviruses by a monoclonal antibody-based enzyme immunoassay. A total of 176 fecal specimens collected from healthy children in similar age group were studied as controls. RESULTS: Rotavirus antigen was detected in 15.3% of patients. Infants between 6 and 12 months of age were most frequently affected. Rotavirus infection was significantly less frequent in breast-fed than among bottle-fed babies. Watery diarrhea was present in 68.5% of children. Detection rate was highest in the spring and lowest in summer. Rotavirus can be regarded as a major etiologic agent of acute diarrhea in infants and children up to 5-years-old in Iran, immunization at birth may protect the children before their first symptomatic infection.

Acute Disease↗
PubMed2006

Rotavirus vaccines: considerations for successful implementation in Europe.

A group of European experts in infectious diseases and vaccinology has met on several occasions to assess the rationale for universal vaccination against rotavirus infection of infants in Europe. On the basis of the available data, we concluded that vaccination was the best approach to prevent severe rotavirus gastroenteritis, and that European countries should consider implementing rotavirus vaccination in their routine immunisation programmes. The main barrier to the implementation of rotavirus vaccination in Europe is a general lack of awareness of stakeholders, policymakers, health-care professionals, and parents about rotavirus disease and the advantages of vaccination. Further studies on the cost of the disease and the benefit of vaccination, together with raising awareness are necessary steps to ensure successful implementation of rotavirus vaccination in Europe.

Europe↗
PubMed1989

Longitudinal study of rotavirus infections among children from Belém, Brazil.

From December 1982 to March 1986 a group of 80 children between 0 and 3 years old who lived in the peripheral area of Belém, Brazil, were followed up for episodes of diarrhoea. A total of 441 diarrhoeal episodes were recorded and 36 (8.2%) were associated with rotavirus. This agent was the only pathogen in 50% of rotavirus-related episodes of acute diarrhoea, and strains were characterized by analysis of RNA in polyacrylamide gels. Forty-one belonged to subgroup II (long pattern) and five to subgroup I. Reinfections by rotavirus were noted in 12 children involving either the same or different subgroups. Ten distinct electrophoretypes were detected in the study period and the predominant one had the '1N2L' profile. The cumulative age-specific attack rate for diarrhoea reached 2.8 by the end of the first year of life; a frequency of 2.3 episodes of diarrhoea per child per year was observed throughout the complete investigation. In comparing the age-specific attack rates for diarrhoea between breast-fed and bottle-fed children, a peak at 6 months of age was noted in the former, and at 1 month in the latter. A comparison by Fischer's exact test (P = 0.21) provided no evidence for protection against clinical rotavirus disease by maternal milk. By the same test, however (P = 0.021), we found significant evidence that early rotavirus infections were more likely to be asymptomatic and that infections after 4 months were more likely to be symptomatic. The clinical picture in children with rotavirus-related diarrhoea was more severe than in those suffering from acute diarrhoea due to another agent.

Acute Disease↗
PubMed1983

Clinical immunity after neonatal rotavirus infection. A prospective longitudinal study in young children.

To determine whether rotavirus infection in newborn babies conferred immunity to postneonatal rotavirus infection, we studied 81 babies at birth and kept them under clinical and serologic study for three years. During the first 14 days of life, 44 of the infants excreted rotavirus, and 37 did not. Fifty-five per cent of those with neonatal infection and 54 per cent of those without it had rotavirus infection during the next three years. Symptoms associated with postneonatal rotavirus infection were significantly less frequent and less severe in the infants who had had neonatal infection (P = 0.003) than in those who had not. Thirty-eight per cent of the former group (9 of 24 infants) had symptoms of mild (3 infants) or moderate (6) severity during the first postneonatal infection. In contrast, 85 per cent of the latter group (17 of 20 infants) had mild (3), moderate (6), or severe (8) symptoms. We conclude that neonatal rotavirus infection does not confer immunity against reinfection but does protect against the development of clinically severe disease during reinfection.

Antibodies, Viral↗
PubMed1996

Rotavirus infection in infants as protection against subsequent infections.

BACKGROUND: Rotavirus is the leading cause of severe diarrhea in infants. To provide a base line for assessing the efficacy of rotavirus vaccines, we evaluated the protection that is conferred by natural rotavirus infection. METHODS: We monitored 200 Mexican infants from birth to two years of age by weekly home visits and stool collections. A physician assessed the severity of any episodes of diarrhea and collected additional stool specimens for testing by enzyme immunoassay and typing of strains. Serum collected during the first week of life and every four months thereafter was tested for antirotavirus IgA and IgG. RESULTS: A total of 316 rotavirus infections were detected on the basis of the fecal excretion of virus (56 percent) or a serologic response (77 percent), of which 52 percent were first and 48 percent repeated infections. Children with one, two, or three previous infections had progressively lower risks of both subsequent rotavirus infection (adjusted relative risk, 0.62, 0.40, and 0.34, respectively) and diarrhea (adjusted relative risk, 0.23, 0.17, and 0.08) than children who had no previous infections. No child had moderate-to-severe diarrhea after two infections, whether symptomatic or asymptomatic. Subsequent infections were significantly less severe than first infections (P=0.024), and second infections were more likely to be caused by another G type (P=0.054). CONCLUSION: In infants, natural rotavirus infection confers protection against subsequent infection. This protection increases with each new infection and reduces the severity of the diarrhea.

Antibodies, Bacterial↗
PubMed2005

Serum IgG mediates mucosal immunity against rotavirus infection.

We evaluated the protective role of passively transferred circulating antibodies in protecting non-human primates against experimental rotavirus infection. Pooled sera with rotavirus-specific IgG titers that were either high (1:10,000), intermediate (1:300), or negative (< 1:25) were infused i.v. into naive pigtailed macaques (ages 3-6 months). Rotavirus-specific IgG could be detected in the sera at 18 h in all animals infused with antibody-containing serum, and fecal IgG titers could be detected only in animals given high-titer pooled sera. When orally challenged with 10(6) fluorescent-forming units of a simian rotavirus strain, YK-1, at 18 h after serum transfer, control animals shed virus starting 1-3 days after challenge and continued to shed virus at high titers for 6-8 days, whereas passively immunized macaques did not shed virus or had delayed shedding at low titers for only a limited time. The observation that passively transferred antibodies can suppress or delay viral infection in rotavirus-challenged pigtailed macaques has important implications for the design and testing of parenteral candidate rotavirus vaccines.

Animals↗
PubMed1997

Prevalence and characteristics of severe rotavirus infections in Nicaraguan children.

We analyzed the prevalence of rotavirus in 296 children age between 3 and 36 months who were hospitalized in 1994 with severe gastro-enteritis at two health centres for diarrhoea treatment in León, Nicaragua. Enteric viruses were detected in 96 (32.4%) of the children and rotaviruses were the most common pathogens detected in 84 (28%). The majority of rotavirus infections occurred in children less than 1 year old and all strains isolated belonged to subgroup II and had 'long' RNA patterns. Molecular epidemiology of 55 rotavirus strains revealed that all had the same RNA migration pattern and serotyping of 37 strains by PCR technology revealed that all isolates belonged to serotype 3. A significant observation was that only one electropherotype of rotavirus circulated. No non-group A rotaviruses were found by RNA gel electrophoresis. Adenoviruses were found by ELISA in 14 of 265 (5%) children and were most frequently detected during the 1st year of life. Of 103 faecal samples analyzed by electron microscopy, four contained small round structured viruses.

Adenovirus Infections, Human↗
PubMed2002

Second-year follow-up evaluation of live, attenuated human rotavirus vaccine 89-12 in healthy infants.

Rotavirus vaccine development is a high priority. The association between the tetravalent rhesus-human reassortant rotavirus vaccine and intussusception has increased the need to develop new vaccines. In a small efficacy trial, the human rotavirus vaccine 89-12 recently has been shown to be safe and effective; 184 of the 215 healthy infants initially enrolled in this trial were followed for a second year. Vaccine efficacy during the second year was 59% (P=.047). For the 2 years of observation, vaccine efficacy was 76% against rotavirus gastroenteritis, 83% against severe rotavirus gastroenteritis, and 100% against rotavirus illnesses requiring medical intervention (P<.001 for each). These encouraging results have led to continued evaluation, in several countries, of a vaccine candidate derived from strain 89-12.

Double-Blind Method↗
PubMed2005

Molecular epidemiological profile of rotavirus in South Korea, July 2002 through June 2003: emergence of G4P[6] and G9P[8] strains.

To determine the distribution of rotavirus strain genotypes in South Korea, rotavirus-positive stool specimens were collected from July 2002 through June 2003 at 8 hospitals in the Korean Rotavirus Strain Surveillance Network, and they were genotyped by means of reverse-transcription polymerase chain reaction. The globally uncommon G4P[6] type was the most prevalent type identified among strains (27% of strains), the newly emerging G9P[8] strain accounted for 11% of strains, and the globally common genotypes (i.e., G1P[8], G2P[4], G3P[8], and G4P[8]) constituted 55% of the strains characterized. Ninety percent of G4P[6] strains were detected in specimens obtained from neonates. Common genotypes were responsible for the rotavirus epidemic that began in January 2003 and ended in May 2003; however, an early peak in infections with the G4P[6] strain occurred from August through October 2002, and infections with this strain were detected throughout the remaining study period. G4P[6] strains were most commonly identified at 6 urban health care centers, but they were absent from 2 rural health care centers. The newly emerging strain G9P[8] represented a relatively greater proportion of strains identified at a hospital in the central region of Korea and at 2 hospitals in the southern region. The identification of novel rotavirus genotypes in this laboratory-based surveillance study underscores the importance to public health of continued strain surveillance among children for whom prevention of rotavirus infection by vaccination might be considered.

Child, Preschool↗
PubMed2005

Health care costs of diarrheal disease and estimates of the cost-effectiveness of rotavirus vaccination in Vietnam.

BACKGROUND: Rotavirus disease causes a significant health and economic burden worldwide. Several rotavirus vaccines may soon be available for use. A country's decision to introduce these vaccines will depend on its rotavirus disease burden, on the cost of the vaccine, and on the results of an economic assessment of the cost and effectiveness of a rotavirus vaccination program. METHODS: Data on medical and nonmedical direct costs and indirect costs were established in Khanh Hoa Province, Vietnam, and extrapolated to national estimates on the basis of the birth cohort in 2004. The main outcome measures were economic burden and cost-effectiveness ratio (United States dollars per disability-adjusted life-year averted and dollars per life saved) of vaccination. RESULTS: The disease burden is equivalent to an economic burden of an estimated 3.1 million US dollars in medical direct costs, 685,000 US dollars in nonmedical direct costs, and 1.5 million US dollars in indirect costs. From a societal perspective, treatment of rotavirus disease costs an estimated 5.3 million US dollars per year. From the health care system perspective, universal vaccination of infants at a cost of < or = 7.26 US dollars/vaccine dose would be a cost-effective public health intervention, according to the World Bank cost-effectiveness standard for low-income countries (140 US dollars/disability-adjusted life-year). CONCLUSIONS: Vaccination can effectively reduce the disease burden and health care costs of rotavirus-specific diarrhea in Vietnam.

Child, Preschool↗
PubMed2002

An outbreak of diarrhea in a neonatal medium care unit caused by a novel strain of rotavirus: investigation using both epidemiologic and microbiological methods.

OBJECTIVE: In December 1999, an outbreak of diarrhea was reported in a general hospital neonatal medium care unit (NMCU) caused by a novel strain of rotavirus with genotype P[6], G9. An investigation was conducted to determine risk factors for illness among neonates. DESIGN: Rotavirus diagnosis was by latex agglutination and typing by reverse transcriptase polymerase chain reaction. A case-control study was performed using data collected from medical records on exposures in a 3-day period before illness (cases) or a random 3-day period (controls). Environmental swabs were tested for rotavirus. Antenatal blood samples from mothers and blood samples provided by hospital staff were analyzed for rotavirus antibodies. RESULTS: Fifty-six cases of rotaviral illness were confirmed by latex agglutination. Forty-seven of these were among 118 neonates exposed to the NMCU (attack rate, 40%). There was a 4-week period with no clinical cases in the course of the outbreak. Increased frequency (> or = 15 times in 3 days) of ungloved nasogastric feeding was a significant risk factor (adjusted odds ratio, 8.79), controlling for birth weight and gestational age. Environmental sampling showed persistence of the virus on ward surfaces despite cleaning. None of 24 NMCU staff members had high levels of antibodies against P[6], G9. Three (8%) of 38 mothers had high antibody levels; 2 had infants who became ill. The outbreak ended with a 7-day ward closure, disinfection, and introduction of gloved nasogastric feeding. CONCLUSIONS: Case-control studies can be successful in identiffying risk factors for nosocomial outbreaks of diarrhea. High levels of rotavirus antibodies in mothers may not protect infants. The environment may be the most important reservoir of rotavirus during outbreaks.

Case-Control Studies↗
PubMed2006

Lactobacilli expressing variable domain of llama heavy-chain antibody fragments (lactobodies) confer protection against rotavirus-induced diarrhea.

BACKGROUND: Rotavirus-induced diarrhea poses a worldwide medical problem in causing substantial morbidity and mortality among children in developing countries. We therefore developed a system for passive immunotherapy in which recombinant lactobacilli constitutively express neutralizing variable domain of llama heavy-chain (VHH) antibody fragments against rotavirus. METHODS: VHH were expressed in Lactobacillus paracasei, in both secreted and cell surface-anchored forms. Electron microscopy was used to investigate the binding efficacy of VHH-expressing lactobacilli. To investigate the in vivo function of VHH-expressing lactobacilli, a mouse pup model of rotavirus infection was used. RESULTS: Efficient binding of the VHH antibody fragments to rotavirus was shown by enzyme-linked immunosorbent assay and scanning electron microscopy. VHH fragments expressed by lactobacilli conferred a significant reduction in infection in cell cultures. When administered orally, lactobacilli-producing surface-expressed VHH markedly shortened disease duration, severity, and viral load in a mouse model of rotavirus-induced diarrhea when administered both fresh and in a freeze-dried form. CONCLUSIONS: Transformed lactobacilli may form the basis of a novel form of prophylactic treatment against rotavirus infections and other diarrheal diseases.

Animals↗
PubMed1988

Evaluation of three commercially available rotavirus detection methods for neonatal specimens.

Commercially available assay kits have now made detection of rotavirus in stool specimens possible as a routine laboratory test. One such kit, Rotazyme II (Abbott Laboratories, North Chicago, IL) has been reported to give a higher incidence of false positive results with neonatal stool than with stool from older patients. One hundred stool specimens from asymptomatic neonates (age range, two to five days) were tested by two ELISA methods and one latex agglutination method in order to evaluate the rate of false positivity in this group of patients. Negative staining electron microscopy was used as the reference method. The two ELISA methods were Rotazyme II and Rotavirus EIA (International Diagnostic Laboratories, St. Louis, MO), and the latex agglutination method was Meritec-Rotavirus (Meridian Diagnostics, Inc., Cincinnati, OH). The Rotavirus EIA and Meritec-Rotavirus tests gave 0% and 1% false positive results, respectively, while the Rotazyme II test gave a 4% false positive rate with an additional 19% equivocal results. This extensive comparative analysis of commercially available assays for detection of rotavirus in neonatal stool specimens suggests a false positive or equivocal rate with the Rotazyme II test that impairs clinical utility.

Diarrhea, Infantile↗