Rotaviruses detected by reverse transcription polymerase chain reaction in acute gastroenteritis during a trial of rhesus-human reassortant rotavirus tetravalent vaccine: implications for vaccine efficacy analysis

Rotavirus Vaccine Is Effective Against Rotavirus Gastroenteritis Resulting in Outpatient Care: Results From the Medically Attended Acute Gastroenteritis (MAAGE) Study

BACKGROUND

Rotavirus is a common cause of severe pediatric acute gastroenteritis. Two vaccines are licensed in the United States and have demonstrated high effectiveness against moderate to severe disease. However, fewer data are available on rotavirus vaccine effectiveness (VE) against milder disease.

METHODS

We leveraged active surveillance data from Kaiser Permanente Northwest to calculate rotavirus VE against medically attended rotavirus illness among age-eligible children. We utilized a test-negative case-control design and applied 4 distinct case definitions based on reverse transcription-quantitative real-time PCR (qRT-PCR) assay and enzyme immunoassay (EIA) test results. VE was calculated as 100 × (1 - odds ratio), and models were adjusted for age group.

RESULTS

The VE analysis population comprised 842 children, 799 (95%) of whom had mild disease requiring at most a clinic visit and 698 (83%) of whom were fully vaccinated against rotavirus. Age-adjusted VE was 70% (95% confidence interval [CI], 37-86%) against disease defined solely by qRT-PCR results, 72% (95% CI, 31-89%) against disease as defined by qRT-PCR with a quantification cycle (C q ) value <27, 73% (95% CI, 32-90%) against disease that was qRT-PCR positive but EIA negative, and 62% (95% CI, -20-88%) against disease defined solely by EIA. Results were similar when restricting to disease resulting in at most an ambulatory clinic or emergency department visit.

CONCLUSIONS

These results support the effectiveness of rotavirus vaccination in protecting US children from mild to moderate and severe disease. Our findings are also useful to show the effectiveness of rotavirus vaccination against qRT-PCR-defined illness.

Sensitive and specific nested PCR assay for detection of rotavirus A in samples with a low viral load

Techniques such as the real-time reverse transcription-polymerase chain reaction (qRT-PCR) can detect RNA in samples with a low viral load. However, these amplicons typically are either too short or at insufficient concentrations for use in subsequent sequencing reactions for genotyping and detection confirmation. The assay developed in this study detects rotavirus G genotypes and P genotypes with viral loads as low as 6.2 and 8.2 copies per reaction, respectively. The assay was validated using a panel of 91 stool samples, 32 reference rotavirus strains, and 6 non-target enteric virus samples.

Immune responses elicited against rotavirus middle layer protein VP6 inhibit viral replication in vitro and in vivo

Rotavirus (RV) is a common cause of severe gastroenteritis (GE) in children worldwide. Live oral RV vaccines protect against severe RVGE, but the immune correlates of protection are not yet clearly defined. Inner capsid VP6 protein is a highly conserved, abundant, and immunogenic RV protein, and VP6-specific mucosal antibodies, especially IgA, have been implicated to protect against viral challenge in mice. In the present study systemic and mucosal IgG and IgA responses were induced by immunizing BALB/c mice intranasally with a combination of recombinant RV VP6 protein (subgroup II [SGII]) and norovirus (NoV) virus-like particles (VLPs) used in a candidate vaccine. Following immunization mice were challenged orally with murine RV strain EDIMwt (SG non-I-non-II, G3P10[16]). In order to determine neutralizing activity of fecal samples, sera, and vaginal washes (VW) against human Wa RV (SGII, G1P1A[8]) and rhesus RV (SGI, G3P5B[3]), the RV antigen production was measured with an ELISA-based antigen reduction neutralization assay. Only VWs of immunized mice inhibited replication of both RVs, indicating heterotypic protection of induced antibodies. IgA antibody depletion and blocking experiments using recombinant VP6 confirmed that neutralization was mediated by anti-VP6 IgA antibodies. Most importantly, after the RV challenge significant reduction in viral shedding was observed in feces of immunized mice. These results suggest a significant role for mucosal RV VP6-specific IgA for the inhibition of RV replication in vitro and in vivo. In addition, these results underline the importance of non-serotype-specific immunity induced by the conserved subgroup-specific RV antigen VP6 in clearance of RV infection.

Sensitive and specific quantitative detection of rotavirus A by one-step real-time reverse transcription-PCR assay without antecedent double-stranded-RNA denaturation

A real-time quantitative reverse transcription-PCR (qRT-PCR) assay using the recombinant thermostable Thermus thermophilus (rTth) enzyme was developed to detect and quantify rotavirus A (RVA). By using rTth polymerase, significant improvement was achieved over the existing real-time RT-PCR assays, which require denaturation of the RVA double-stranded RNA (dsRNA) prior to assay setup. Using a dsRNA transcript for segment 7, which encodes the assay target NSP3 gene, the limit of detection for the improved assay was calculated to be approximately 1 genome copy per reaction. The NSP3 qRT-PCR assay was validated using a panel of 1,906 stool samples, 23 reference RVA strains, and 14 nontarget enteric virus samples. The assay detected a diverse number of RVA genotypes and did not detect other enteric viruses, demonstrating analytical sensitivity and specificity for RVA in testing stool samples. A XenoRNA internal process control was introduced and detected in a multiplexed qRT-PCR format. Because it does not require an antecedent dsRNA denaturation step, this assay reduces the possibility of sample cross-contamination and requires less hands-on time than other published qRT-PCR protocols for RVA detection.

Prevalence of rotavirus and adenovirus associated with diarrhea among displaced communities in Khartoum, Sudan

BACKGROUND

Diarrheal diseases represent a major worldwide public health problem particularly in developing countries. Each year, at least four million children under five years of age die from diarrhea. Rotavirus, enteric adenovirus and some bacterial species are the most common identified infectious agents responsible for diarrhea in young children worldwide. This study was conducted to determine prevalence of rotavirus and adenovirus associated with diarrhea among displaced communities in Khartoum state, Sudan.

METHODS

A total of seven hundred and ten patients, children and adults, suffering from diarrhea were examined. The clinical history, socio-demographic characteristics, physical examination findings and laboratory investigations were recorded. Stool samples or rectal swabs were collected and tested for rotavirus and adenovirus antigens using the immuno-chromatography test (ICT). Characterization of the identified Rotaviruses, as a major cause of diarrhea, was then made using real time-reverse transcription PCR. To make the study legal, an ethical clearance was obtained from Sudan Ministry of health- Research Ethical Committee. Written consent was taken from adult subjects, and also from children mothers.The participants were informed using simple language about the infection, aim of the research and the benefits of the study.

RESULTS

Out of the 710 patients, viral pathogens were detected in only 99 cases (13.9%). Of the 99 cases of viral diarrhea, 83 (83.8%) were due to rotaviruses while 16 (16.2%) attributed to adenovirus. Of the 83 rotaviruses identified, 42 were characterized by RT-PCR, of these 40 (95.2%) were proved as type A (VP6), and 2 (4.8%) type C (VP7). Type C (VP7) rotavirus was detected in samples collected from children under 5 years only.

CONCLUSIONS

In conclusion, most cases of viral diarrhea are found to be caused by rotavirus especially among children less than five years. Most of the identified rotavirus belonged to type A (VP6).It was also evident that most patients are those who drank untreated water obtained from donkey carts source and who had no access to latrines, and lived in poor environmental conditions would acquire diarrheal infection.

Multiplex real-time PCR assays for the detection of group C rotavirus, astrovirus, and Subgenus F adenovirus in stool specimens

Group C rotavirus (GCRV), astrovirus (AstV), and adenovirus (subgenus F AdenoV) are etiologic agents of acute nonbacterial gastroenteritis, which often represents community outbreaks. For the efficient detection of GCRV, AstV, and subgenus F AdenoV in stool specimens, a multiplex real-time PCR assay was developed to detect these three viruses simultaneously, with high sensitivity and specificity. In total, 8404 clinical specimens were collected between April 2008 and March 2011 and tested for GCRV, AstV, and subgenus F AdenoV by the multiplex real-time PCR, as well as for norovirus (NoV), sapovirus (SaV), and group A rotavirus (GARV) by non-multiplex real-time PCR. Forty-one specimens were positive for GCRV, AstV, or subgenus F AdenoV, including 15 specimens that were also positive for NoV, SaV, or GARV. Multiple viruses were detected simultaneously in 29 out of 4596 (0.63%) specimens infected with at least one virus. The association rates of AstV and subgenus F AdenoV with other viruses were significantly higher than those of NoV, SaV, GARV, or GCRV.

Simultaneous presence of human herpesvirus 6 and adenovirus infections in intestinal intussusception of young children

AIM

This prospective study investigated the role of viral infections in the pathogenesis of intussusception, including human herpesvirus 6 (HHV-6), a known lymphotropic virus.

METHODS

Fifty-three children with intussusception treated in hospital were enroled, and children of comparable age and gender served as controls. Blood, stool and throat swab specimens, as well as mesenteric lymph nodes and pieces of intestine from patients requiring surgery were tested for various viruses by PCR methods.

RESULTS

Altogether, 85% of intussusception cases showed evidence of a recent or ongoing viral infection. Among the 53 intussusception cases, adenovirus was detected in 25 (47%), HHV-6 in 24 (45%), rhinovirus in 12 (23%), cytomegalovirus in 7 (13%), enterovirus in 4 (8%) and rotavirus in 3 (6%) patients. Of the 50 whole blood samples, 44% were positive for HHV-6 and of the 16 resected mesenteric lymph nodes, 50% were positive for HHV-6. Simultaneous presence of HHV-6 and adenovirus infection correlated significantly with intussusception (OR 12.1, 95% CI 2.2 to 66.5).

CONCLUSIONS

A statistically significant association was observed between adenovirus and childhood intussusception. HHV-6 was a common finding and occurred concomitantly with other viruses. A simultaneous infection with HHV-6 and adenovirus carried the highest risk for intussusception.

Transaminase in rotavirus gastroenteritis

BACKGROUND

Children infected with rotavirus often show increased levels of transaminase, and symptoms are characterized by white stool, similar to biliary atresia. Rotavirus infections are also sporadically accompanied with convulsions, encephalopathy and Reye syndrome. The aim of the present study was therefore to investigate transaminase and interleukin (IL)-6 levels in rotavirus infection, in order to better understand their clinical significance.

METHODS

Results of liver function tests, mainly the elevation of transaminase and IL-6 in rotavirus gastroenteritis with or without convulsions, were evaluated.

RESULTS

Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were high in 23 of 26 samples (88.5%), and in three of 26 samples (11.5%), respectively. No significant differences in liver function tests could be found between the groups with or without convulsions. Three patients whose direct bilirubin levels were above the upper normal limit were all classified into the group without convulsions. Spearman's correlation coefficient was 0.89 between increasing AST levels and IL-6 levels.

CONCLUSION

Rotavirus infection is occasionally accompanied with hepatitis, but only in a mild form, and does not correlate with neurological complications. High levels of transaminase might reflect high IL-6.

Evaluation of a multiplex real time reverse transcription PCR assay for the detection and quantitation of the most common human rotavirus genotypes

Group A rotaviruses (RVs) are important pathogens that cause acute, dehydrating gastroenteritis in infants and young children. In this study, a multiplex real-time polymerase chain reaction protocol using primers and TaqMan(®) probes specific for viral VP4 and VP7 genes was evaluated. This assay offers simultaneous genotyping and quantification of the most common RV genotypes G1P[8], G2P[4], G3P[8], G4P[8], and G9P[8]. It was compared to the molecular typing results provided by conventional PCR. A total of 92 archived stool specimens obtained from children younger than 5 years old with the diagnosis of acute gastroenteritis were examined. Real-time PCR assay detected rotavirus strains among the most common genotype combinations G4P[8] (70.7%), G1P[8] (10.9%), G2P[4] (5.4%), G9P[8] (2.2%). This new assay described has an acceptable sensitivity (low limit 6.3×10(2)copies/g of stool).

Noroviruses as a major cause of acute gastroenteritis in children in Finland, 2009-2010

Noroviruses are, after rotaviruses, the second most common cause of acute gastroenteritis in young children. In a prospective study conducted in 2009-2010 at the Tampere University Hospital, 195 stool specimens were collected from cases of acute gastroenteritis in children and examined for noroviruses, sapoviruses, and rotaviruses, using a reverse transcriptase polymerase chain reaction (RT-PCR). Noroviruses were found in 49 (25%) of the cases and sapoviruses in 12 (6%). The norovirus genotype GII.4 dominated with a 76% share; other genotypes detected were GII.7/GII.6 (16%), GII.g/GII.12, GII.e/GII.4, and GII.7 (2% each). For comparison, 47 (24%) cases of rotavirus gastroenteritis were diagnosed in the same period. In conclusion, after the introduction of rotavirus vaccination in Finland in September 2009, noroviruses have become as common as rotaviruses as the causative agents of acute gastroenteritis in young children, and are likely to become the leading cause. Norovirus GII.4 continues to be the dominant genotype.

Evaluation of a gastroenteritis severity score for use in outpatient settings

OBJECTIVE

The objective of this study was to evaluate the internal reliability, construct validity, and ease of administration of a gastroenteritis disease severity score, the modified Vesikari score (MVS), which does not require in-person assessment.

METHODS

The MVS was created by replacing 1 variable (percent dehydration) in the original score with the need for future health care visits. We used the MVS to assess the global severity of disease in a cohort of children 3 to 48 months of age with acute gastroenteritis who were evaluated in 1 of 11 participating pediatric emergency departments. In this prospective study, caregivers recorded symptoms at home in a diary and reported the results via telephone at follow-up evaluation 14 days later. To evaluate internal reliability, we examined correlations between the items included in the score. Construct validity was evaluated by assessing the correlation between the total score and other proxy outcomes of disease severity, MVS distribution, and consistency between sites.

RESULTS

A total of 455 children were enrolled, and 415 were successfully contacted for follow-up evaluation. Internal reliability was acceptable, with Cronbach's alpha of 0.59. Disease severity was correlated with day care (P = .01) and work (P = .002) absenteeism. The MVS was normally distributed, and mean scores did not differ between the 11 sites.

CONCLUSIONS

The MVS seems to measure effectively the global severity of disease in a cohort of children with acute gastroenteritis. These data support the use of the MVS as an outcome measure in future clinical trials.

Effect of human rotavirus vaccine on severe diarrhea in African infants

BACKGROUND

Rotavirus is the most common cause of severe gastroenteritis among young children worldwide. Data are needed to assess the efficacy of the rotavirus vaccine in African children.

METHODS

We conducted a randomized, placebo-controlled, multicenter trial in South Africa (3166 infants; 64.1% of the total) and Malawi (1773 infants; 35.9% of the total) to evaluate the efficacy of a live, oral rotavirus vaccine in preventing severe rotavirus gastroenteritis. Healthy infants were randomly assigned in a 1:1:1 ratio to receive two doses of vaccine (in addition to one dose of placebo) or three doses of vaccine--the pooled vaccine group--or three doses of placebo at 6, 10, and 14 weeks of age. Episodes of gastroenteritis caused by wild-type rotavirus during the first year of life were assessed through active follow-up surveillance and were graded with the use of the Vesikari scale.

RESULTS

A total of 4939 infants were enrolled and randomly assigned to one of the three groups; 1647 infants received two doses of the vaccine, 1651 infants received three doses of the vaccine, and 1641 received placebo. Of the 4417 infants included in the per-protocol efficacy analysis, severe rotavirus gastroenteritis occurred in 4.9% of the infants in the placebo group and in 1.9% of those in the pooled vaccine group (vaccine efficacy, 61.2%; 95% confidence interval, 44.0 to 73.2). Vaccine efficacy was lower in Malawi than in South Africa (49.4% vs. 76.9%); however, the number of episodes of severe rotavirus gastroenteritis that were prevented was greater in Malawi than in South Africa (6.7 vs. 4.2 cases prevented per 100 infants vaccinated per year). Efficacy against all-cause severe gastroenteritis was 30.2%. At least one serious adverse event was reported in 9.7% of the infants in the pooled vaccine group and in 11.5% of the infants in the placebo group.

CONCLUSIONS

Human rotavirus vaccine significantly reduced the incidence of severe rotavirus gastroenteritis among African infants during the first year of life. (ClinicalTrials.gov number, NCT00241644.)

Aichi virus infection in children with acute gastroenteritis in Finland

Aichi virus has been proposed as a novel causative agent of acute gastroenteritis. In addition to several Asian countries, South America and Africa, Aichi virus has also recently been found in Europe. Our objective was to study the causative role of Aichi virus in children with acute gastroenteritis in Finland. We analysed 595 stool specimens from infants in an efficacy trial of rotavirus vaccine and 468 stool specimens from children in a hospital-based epidemiological and aetiological study of acute gastroenteritis. The screening was done by nested reverse transcription-polymerase chain reaction amplifying a 519-bp segment and a 223-bp segment in the 3CD junction region of non-structural proteins. Aichi virus was detected in five stool samples (0.5%), of which four were co-infections with other gastroenteritis viruses. Two Aichi virus genotypes, A and B, were found. Aichi virus appears to be rare in children with acute gastroenteritis in Finland.

Closing the diarrhoea diagnostic gap in Indian children by the application of molecular techniques

A large proportion of diarrhoeal illnesses in children in developing countries are ascribed to an unknown aetiology because the only available methods, such as microscopy and culture, have low sensitivity. This study was aimed at decreasing the diagnostic gap in diarrhoeal disease by the application of molecular techniques. Faecal samples from 158 children with and 99 children without diarrhoea in a hospital in South India were tested for enteric pathogens using conventional diagnostic methods (culture, microscopy and enzyme immunoassays) and molecular methods (six PCR-based assays). The additional use of molecular techniques increased identification to at least one aetiological agent in 76.5 % of diarrhoeal specimens, compared with 40.5 % using conventional methods. Rotavirus (43.3 %), enteropathogenic Escherichia coli (15.8 %), norovirus (15.8 %) and Cryptosporidium spp. (15.2 %) are currently the most common causes of diarrhoea in hospitalized children in Vellore, in contrast to a study conducted two decades earlier in the same hospital, where bacterial pathogens such as Shigella spp., Campylobacter spp. and enterotoxigenic E. coli were more prevalent. Molecular techniques significantly increased the detection rates of pathogens in children with diarrhoea, but a more intensive study, testing for a wider range of infectious agents and including more information on non-infectious causes of diarrhoea, is required to close the diagnostic gap in diarrhoeal disease.

One-step quantitative RT-PCR for the detection of rotavirus in acute gastroenteritis

The standard diagnosis of rotavirus gastroenteritis is based on the demonstration of rotavirus antigen in stools using an enzyme immunoassay (EIA). In this study, a one-step quantitative RT-PCR (Q-PCR) was used for sensitive detection of rotavirus in diarrheal stools. The primers and TaqMan probe for the Q-PCR were selected from a highly conserved region of the non-structural protein 3 (NSP3) of rotavirus. After validation, the test was applied to study rotavirus EIA positive (N=25) and EIA negative (N=143) stool specimens from cases of acute gastroenteritis of all degrees of severity in a prospective follow-up cohort of infants from 2 months to 2 years of age. Q-PCR detected all 25 EIA positive rotavirus antigens and seven additional cases that were rotavirus EIA negative, i.e. 28% more rotavirus positive cases than identified by EIA. It is concluded that Q-PCR using primers targeted at NSP3 is a rapid and sensitive method for diagnosing acute rotavirus gastroenteritis.

Real-time reverse transcription-PCR for detection of rotavirus and adenovirus as causative agents of acute viral gastroenteritis in children

Viral pathogens are the most common cause of gastroenteritis in developed countries. Human rotavirus and adenovirus infections are major causes of acute outbreaks and sporadic cases of gastroenteritis, occurring primarily among children less than 2 years of age. Patient hospitalization is often required, with enormous infection control implications. This work describes the development of real-time PCR assays for the detection of group F adenovirus, rotavirus A, and rotavirus C from stool specimens. Two hundred twenty stool samples from pediatric patients exhibiting symptoms of diarrhea and/or vomiting were examined. PCR results were compared with those of virus detection by electron microscopy and latex agglutination antigen detection. The incorporation of an internal-control RNA that was spiked into individual stool extracts functioned as an internal validation for the reporting of PCR-negative results. Rotavirus C was not detected by real-time PCR in the patient stool samples examined. Real-time reverse transcription-PCR resulted in 175% and 111% increases in the rates of detection of adenovirus F and rotavirus A, respectively, compared with latex agglutination testing. Molecular detection increased the number of stool specimens in which causative agents of gastroenteritis were identified by 155% compared to electron microscopy. Genotyping of a proportion of the rotavirus and adenovirus strains identified only genotype G1 rotavirus and both adenovirus genotypes 40 and 41 in circulation within the patient cohort examined. The results highlight the significance of rapid molecular methods for the routine screening of stool samples in hospital laboratories to provide rapid definitive diagnoses.

Safety and efficacy of an attenuated vaccine against severe rotavirus gastroenteritis

BACKGROUND

The safety and efficacy of an attenuated G1P[8] human rotavirus (HRV) vaccine were tested in a randomized, double-blind, phase 3 trial.

METHODS

We studied 63,225 healthy infants from 11 Latin American countries and Finland who received two oral doses of either the HRV vaccine (31,673 infants) or placebo (31,552 infants) at approximately two months and four months of age. Severe gastroenteritis episodes were identified by active surveillance. The severity of disease was graded with the use of the 20-point Vesikari scale. Vaccine efficacy was evaluated in a subgroup of 20,169 infants (10,159 vaccinees and 10,010 placebo recipients).

RESULTS

The efficacy of the vaccine against severe rotavirus gastroenteritis and against rotavirus-associated hospitalization was 85 percent (P<0.001 for the comparison with placebo) and reached 100 percent against more severe rotavirus gastroenteritis. Hospitalization for diarrhea of any cause was reduced by 42 percent (95 percent confidence interval, 29 to 53 percent; P<0.001). During the 31-day window after each dose, six vaccine recipients and seven placebo recipients had definite intussusception (difference in risk, -0.32 per 10,000 infants; 95 percent confidence interval, -2.91 to 2.18; P=0.78).

CONCLUSIONS

Two oral doses of the live attenuated G1P[8] HRV vaccine were highly efficacious in protecting infants against severe rotavirus gastroenteritis, significantly reduced the rate of severe gastroenteritis from any cause, and were not associated with an increased risk of intussusception. (ClinicalTrials.gov numbers, NCT00139347 and NCT00263666.)

Viral etiology and incidence of acute gastroenteritis in young children attending day-care centers

BACKGROUND

The purpose of the study was to investigate the frequency, morbidity and cause of acute gastroenteritis in children attending day-care centers in Denmark.

METHODS

Children with acute diarrhea (> or =2 consecutive loose stools in 24 hours, with duration of < or =7 days), recruited from 19 day-care centers, were included. Gastroenteritis viruses, group A rotavirus, sapoviruses, noroviruses and astroviruses were detected with reverse transcription-polymerase chain reaction assays. In addition, stool specimens were cultured for bacterial pathogens. Children who were brought to the clinic with acute diarrhea underwent a medical evaluation, including an estimation of dehydration.

RESULTS

Two hundred seven children (median age, 20.1 months; range, 9-44 months) were enrolled. During the 6-month study period, 98 diarrheal episodes in 95 children were reported. Of these, 48 were reported retrospectively in telephone interviews. The incidence of acute diarrheal episodes was 0.08 episode per child per month. A viral etiologic agent was identified in 69% of cases. Rotaviruses were identified in 17 cases (40%), sapoviruses in 8 (19%) and astroviruses in 3 (7%). One patient had a coinfection with rotavirus and astrovirus. Campylobacter jejuni was detected in 2 patients and Clostridium difficile was found in 5 patients, all coinfected with a virus. In clinical assessments, 9 patients (18%) showed signs of dehydration and were given oral rehydration solution; 6 of these were hospitalized.

CONCLUSIONS

Acute diarrhea among children attending day-care centers was common in wintertime. Rotaviruses were, expectedly, the most common causative agents, but sapoviruses were second to rotaviruses as etiologic agents in this population.

Evaluation of safety, immunogenicity and efficacy of an attenuated rotavirus vaccine, RIX4414: A randomized, placebo-controlled trial in Latin American infants

BACKGROUND

A live attenuated monovalent rotavirus vaccine RIX4414 was developed with a human strain of G1P1A P[8] specificity to reduce the rotavirus burden in children.

METHODS

A double blind, randomized, placebo-controlled study evaluated the efficacy, immunogenicity, safety and reactogenicity of 2 oral doses of RIX4414 (10(4.7), 10(5.2) or 10(5.8) focus-forming units) at 2 and 4 months coadministered with routine vaccinations and oral poliovirus vaccine given for study purposes at least 14 days apart. The 2155 infants (1618 vaccine/537 placebo) enrolled in Brazil, Mexico and Venezuela were followed until 1 year of age.

RESULTS

Antirotavirus IgA seroconversion rates 2 months after dose 2 ranged between 61% (10(4.7) ffu group) and 65% (10(5.8) ffu group), and most of the infants had seroprotective levels of antibodies to coadministered routine vaccinations. The reactogenicity profile of RIX4414 was similar to that of the placebo, and no vaccination-related serious adverse events were reported. Protective efficacy against severe and any rotavirus gastroenteritis from 15 days post-dose 2 was highest in the 10(5.8) ffu group [86%; 95% confidence interval (95% CI), 63-96% and 70% (95% CI 46-84%), P < 0.001, 2-sided Fisher's exact test]. The efficacy against hospitalization was 79% (95% CI 48-92%) for pooled vaccine groups. Multiple rotavirus serotypes [G1 (50%), G9 (40%), G2, G3 and G4] were identified from gastroenteritis stools (enzyme-linked immunosorbent assay and reverse transcription-polymerase chain reaction) during the study period. For severe gastroenteritis caused by G9 serotypes, the protection reached 77% (95% CI 18-96%) in the 10(5.8) ffu group, providing proof of concept that the monovalent G1P1A P[8] human rotavirus vaccine elicits cross-protection against the G9 strain. A reduction in any and severe rotavirus gastroenteritis was already observed at post-dose 1 (period: day of dose 1 to 14 days post-dose 2) in vaccinees compared with placebo recipients.

CONCLUSIONS

Two doses of RIX4414 are highly efficacious, providing cross-protection (G1 and G9 strains, prevalent during this study) and early protection against any and severe rotavirus gastroenteritis and hospitalization to infants in Latin America.

Evaluation of RIX4414, A Live, Attenuated Rotavirus Vaccine, in a Randomized, Double‐Blind, Placebo‐Controlled Phase 2 Trial Involving 2464 Singaporean Infants

BACKGROUND

At present, no rotavirus vaccine is commercially available for use worldwide. Hence, a live, attenuated monovalent vaccine was developed with human strain RIX4414 (G1P1A P[8] specificity). Vaccination trials involving infants are ongoing in developed and developing countries.

METHODS

This study was a randomized, double-blind, placebo-controlled trial conducted at pediatric hospitals and polyclinics in Singapore for the evaluation of the immunogenicity, reactogenicity, and efficacy of 2 oral doses of RIX4414. In total, 2464 healthy infants (who were 11-17 weeks old when the first dose was administered, which is in accordance with the local immunization schedule) were enrolled to receive RIX4414 at 3 concentrations of virus (10(4.7), 10(5.2), or 10(6.1) focus-forming units) or placebo at 1-month intervals, concomitantly with routinely administered infant vaccines.

RESULTS

The RIX4414 vaccine was highly immunogenic, and virtually all vaccine recipients (98%-100%) experienced "vaccine take" (i.e., a combined immunogenicity end point based on seroconversion and/or shedding of RIX4414 in postvaccination stool samples) after receipt of 2 doses at all 3 dosage levels. Depending on the virus concentration, the anti-rotavirus IgA seroconversion rate varied from 76% (95% confidence interval [CI], 68%-83%) to 91% (95% CI, 85%-95%). Two doses of RIX4414 were well tolerated, with no increase in high fever, severe diarrhea, or vomiting after either dose or with increased viral concentration, compared with placebo. There was no observed interference with routine vaccinations of infants when RIX4414 was coadministered. The calculated efficacy of RIX4414 against rotavirus gastroenteritis was 82% (P = .046); however, this result was considered to be of limited conclusive value because of the low number of rotavirus gastroenteritis episodes identified during the follow-up period.

CONCLUSIONS

The live, attenuated rotavirus vaccine (RIX4414) was well tolerated and highly immunogenic in Singaporean infants. The immunogenicity of routinely administered infant vaccines was not impaired by concomitant administration of RIX4414 vaccine.

Evaluation of rotavirus dsRNA load in specimens and body fluids from experimentally infected juvenile macaques by real-time PCR

We recently established a non-human primate model of rotavirus infection that is characterized by consistent and high levels of virus antigen shedding in stools. Here, we report that starting from post challenge day (PCD) 2, 6 x 10(3) to 1.5 x 10(6) copies of rotavirus double-stranded RNA per nanogram of total RNA were detected by real-time PCR in MA104 cells that were 48 h pre-incubated with filtered stool suspensions of three experimentally infected juvenile macaques. The peak of virus load was detected at PCD 4-5, followed by decreased load at PCD 6-11, and very low levels at PCD 12. Such a pattern corresponded to virus shedding in stools as reported recently based on enzyme-linked immunosorbent assay (ELISA) results. In addition, plasma and cerebrospinal fluids (CSF) from six infected animals were tested for the presence of rotavirus. Rotavirus extraintestinal escape was revealed in three out of six animals by a combination of real-time and nested PCR. However, very low quantities of detected viral RNA (approximately 20 copies/ng of total RNA) were not suggestive of viremia. Thus, the rhesus model of rotavirus infection can be exploited further in studies with vaccine candidates designed to prevent or abrogate rotavirus infection.

Efficacy of RIX4414 live attenuated human rotavirus vaccine in Finnish infants

BACKGROUND

Rotavirus gastroenteritis, a major cause of mortality and morbidity worldwide, is a vaccine-preventable disease. New safe and effective candidate rotavirus vaccines are needed to replace the withdrawn rhesus rotavirus-based oral vaccine.

METHODS

We evaluated a monovalent human rotavirus vaccine, serotype G1, strain RIX4414, for efficacy, immunogenicity and safety in a randomized, double blind, placebo-controlled trial in Finland. We randomly allocated 405 healthy infants to receive 2 doses of vaccine or placebo (ratio 2:1) at approximately 2 and 4 months of age. The infants were followed during 2 rotavirus epidemic seasons (2000-2002) for acute gastroenteritis. Rotaviruses in diarrheal stool samples were primarily detected by enzyme-linked immunosorbent assay and confirmed and G-typed by reverse transciption-polymerase chain reaction.

RESULTS

The vaccine was well-tolerated. No vaccine-related serious adverse events were observed during the study period. Rotavirus IgA (enzyme-linked immunosorbent assay) seroconversion rate was 80% after 2 doses. Thirty-eight cases of rotavirus gastroenteritis were detected during the entire follow-up period; 35 of these were of the G1 type. RIX4414 vaccine significantly decreased the occurrence of any rotavirus compared with placebo. Efficacy during the first rotavirus epidemic season was 73% [95% confidence interval (95% CI), 27-91%] and 90% (95% CI 10-100%) against any and severe rotavirus gastroenteritis, respectively, and during the entire follow-up period 72% (95% CI 42-87%) against any and 85% (95% CI 42-97%) against severe rotavirus gastroenteritis (P < 0.05 for all comparisons).

CONCLUSIONS

RIX4414 strain of G1 human rotavirus vaccine was well-tolerated, immunogenic and efficacious in infants against rotavirus gastroenteritis during a 2-year period. To further increase vaccine "take" and efficacy, a higher dose of this vaccine may be considered for future efficacy trials.

A rotavirus vaccine for prophylaxis of infants against rotavirus gastroenteritis

The need for safe and effective vaccines to reduce morbidity and mortality caused by rotavirus gastroenteritis in children is well-known. A live attenuated monovalent rotavirus vaccine (Rotarix) containing human rotavirus strain RIX4414 of G1P1A P[8] specificity is being developed to meet the global need. An overview of RIX4414 trials in developed and developing settings is presented for 3 selected trials conducted in Finland (pilot study), Latin America (Brazil, Mexico and Venezuela) and Singapore involving 5024 infants. The vaccine was well-tolerated, with no increase in any solicited symptoms as compared with the placebo. After 2 doses, 61-91% of vaccinated infants developed rotavirus-specific IgA antibodies. There was no interference with immunogenicity of coadministered routine pediatric vaccines. Rotarix significantly reduced rotavirus gastroenteritis episodes and rotavirus-related hospitalizations in vaccinated infants compared with placebo recipients (P < 0.05). Vaccine efficacy was observed against severe rotavirus gastroenteritis caused by G1 and non-G1 types including the emerging G9 type (P < 0.05) in Latin America. These results show prospects for widespread use of Rotarix to reduce rotavirus disease burden and warrant continued worldwide evaluation.

Estimating hospital admissions due to rotavirus gastroenteritis from hospital episode statistics

OBJECTIVES

To determine the proportion of hospital admissions, in children < 5 years old, coded for intestinal infectious disease or non-infectious gastroenteritis, using ICD-10 codes, that were due to rotavirus infection. To assess how many children admitted with rotavirus gastroenteritis were given the specific ICD-10 code (A080) for this disease.

METHODS

Sixteen-month prospective, observational study of children < 5 years old, admitted to district general hospital with: acute gastroenteritis (> or =3 loose stools/day), proven rotavirus infection and those coded as intestinal infectious disease or non-infectious gastroenteritis.

RESULTS

Four hundred and twenty children < 5 years old were admitted with acute gastroenteritis. Rotavirus was detected in 170 children's stools. Acute rotavirus gastroenteritis accounted for 81/397 (20%) children coded as having non-infectious gastroenteritis and 32/81 (40%) coded for intestinal infectious disease. Only 18 children were coded for rotavirus gastroenteritis. Potentially preventable rotavirus gastroenteritis occurred in 122 children; 78 coded as non-infectious gastroenteritis (20%) and 26 coded for intestinal infectious disease (34%).

CONCLUSIONS

The proportion of children coded with diarrhoeal diseases and found to have rotavirus is less than previously estimated. Using the specific code for rotavirus infection to estimate hospital admissions would be a gross underestimate. Hospital episode statistics cannot reliably estimate the burden of disease due to rotavirus.

Increased detection of rotavirus using a real time reverse transcription-polymerase chain reaction (RT-PCR) assay in stool specimens from children with diarrhea

Six-hundred and twenty-six stool specimens collected from children with diarrhea over a 12-month period were tested for rotavirus using a real time reverse transcription-polymerase chain reaction (RT-PCR) assay, a conventional nested PCR assay and by electron microscopy (EM). A fragment of 87 bp in a highly-conserved region of non-structural protein 3 (NSP3) in rotavirus genome was amplified by a single-step RT-PCR protocol in a closed-tube system. Rotavirus was detected in 123 samples (20%) with the real time RT-PCR assay, 113 samples (18%) with the nested-PCR assay, and 79 samples (13%) with EM. Using serial diluted nucleic acid extract, we compared the sensitivity of real time RT-PCR with conventional RT-PCR and conventional nested PCR assays. Real time RT-PCR was two to four logs more sensitive than the conventional assays. The reaction time required for the RT-PCR assay is about half the time required for the conventional nested-PCR. The real time RT-PCR assay is both simple and rapid with advantages including enhanced sensitivity and a lower risk for cross-contamination making it a useful tool for the detection of rotavirus in various situations including sporadic gastroenteritis, outbreaks, and environmental investigations. G(1) was the predominant type (89%), followed by G(2) (10%), and G(4) (1%). No rotavirus of G(3), G(8), and G(9) types were found. The peak season for rotavirus infection was January to May in northern Alberta.

Rotavirus vaccine for preventing diarrhoea

BACKGROUND

Rotaviruses cause viral gastroenteritis and result in more deaths from diarrhoea in children under 5 years of age than any other single agent, particularly in low- and middle-income countries.

OBJECTIVES

To assess rotavirus vaccines in relation to preventing rotavirus diarrhoea, death, and adverse events.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group's trial register (October 2003), the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 3, 2003), MEDLINE (1966 to October 2003), EMBASE (January 1980 to October 2003), LILACS (1982 to October 2003), Biological Abstracts (January 1982 to October 2003), reference lists of articles, and contacted researchers and rotavirus vaccine manufacturers.

SELECTION CRITERIA

Randomized controlled trials comparing rotavirus vaccines to placebo, no intervention, or other rotavirus vaccines in children and adults.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed trial methodological quality, and contacted trial authors for additional information.

MAIN RESULTS

Sixty-four trials provided information on efficacy and safety of three main types of rotavirus vaccine (bovine, human, and rhesus) for 21,070 children. Different levels of efficacy were demonstrated with different vaccines varying from 22 to 89% to prevent one episode of rotavirus diarrhoea, 11 to 44% to prevent one episode of all-cause diarrhoea, and 43 to 90% to prevent one episode of severe rotavirus diarrhoea. Rhesus vaccine demonstrated a similar efficacy against one episode of rotavirus diarrhoea (37 and 44% respectively), and one episode of all-cause diarrhoea (around 15%) for trials performed in high and middle-income countries. Results on mortality and safety of the vaccines were scarce and incomplete. We noticed important heterogeneity among the pooled studies and were unable to discard a biased estimation of effect.

REVIEWER'S CONCLUSIONS

Current evidence shows that rhesus rotavirus vaccines (particularly RRV-TV) and the human rotavirus vaccine 89-12 are efficacious in preventing diarrhoea caused by rotavirus and all-cause diarrhoea. Evidence about safety, and about mortality or prevention of severe outcomes, is scarce and inconclusive. Bovine rotavirus vaccines were also efficacious, but safety data are not available. Trials of new rotavirus vaccines will hopefully improve the evidence base. Randomized controlled trials should be performed simultaneously in high-, middle-, and low-income countries.

Viruses causing gastroenteritis

Acute gastroenteritis is one of the most common diseases in humans worldwide. Viruses are recognized as important causes of this disease, particularly in children. Since the Norwalk virus was identified as a cause of gastroenteritis, the number of viral agents associated with diarrheal disease in humans has steadily increased. Rotavirus is the most common cause of severe diarrhea in children under 5 years of age. Astrovirus, calicivirus and enteric adenovirus are also important etiologic agents of acute gastroenteritis. Other viruses, such as toroviruses, coronaviruses, picobirnaviruses and pestiviruses, are increasingly being identified as causative agents of diarrhea. In recent years, the availability of diagnostic tests, mainly immunoassays or molecular biology techniques, has increased our understanding of this group of viruses. The future development of a safe and highly effective vaccine against rotavirus could prevent, at least, cases of severe diarrhea and reduce mortality from this disease.

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.

Viral causes of diarrhea

Viruses are important causes of diarrhea. In healthy adults, the main clinical manifestation is acute, self-limited gastroenteritis. Advances in molecular diagnostics have shown that epidemics of acute gastroenteritis most frequently are due to caliciviruses spread through contaminated food or through person-to-person contact. Application of similar technology is needed to make a definitive statement about the role of such candidate viruses as rotavirus, astrovirus, and adenovirus as the cause of nonepidemic acute gastroenteritis in adults. Rarely a previously healthy adult gets acute CMV colitis. CMV and EBV mainly cause diarrhea in immunocompromised patients, however. Advances in prophylaxis and treatment have reduced the frequency and severity of these diseases. Acute infantile gastroenteritis is caused by rotavirus, calcivirus, astrovirus, and adenovirus. These viral diseases of the gut are seen by the physician as routine and rare clinical problems.

Effect of rotavirus vaccine on Sapporo virus gastroenteritis in Finnish infants

BACKGROUND

Sapporo-like viruses (SLVs) occur worldwide, but there is limited information about the SLV-associated gastroenteritis outside Japan.

METHODS

Stool specimens from 1,432 episodes of gastroenteritis that occurred in children between 2 months and 2 years of age during a rotavirus vaccine trial (776 episodes in placebo-vaccinated and 656 in rotavirus-vaccinated infants) were examined for SLVs using a reverse transcription-PCR assay. The reverse transcription-PCR took advantage of new primers specific for Sapporo virus genetic clusters I, II and III; SV/SV82 (SV/Sapporo virus 82); SV/Lond92 (SV/ London 92); and SV/PV (Parkville virus).

RESULTS

SLVs were detected in association with 132 (9.2%) of all episodes; in 80 (5.6%) episodes SLV was the only gastroenteritis virus detected. The epidemic season of SLVs peaked from March to May concurrently with rotaviruses and astroviruses and overlapping withNorwalk-like viruses. Clinically SLV gastroenteritis was characterized by a mild diarrheal disease, being sharply different from the Norwalk-like virus-associated "winter vomiting disease." Rotavirus vaccination did not have any effect on the number of SLV episodes, but the intensity and duration of SLV-associated diarrhea were reduced in rotavirus-vaccinated children compared with placebo-vaccinated children (P = 0.0008).

CONCLUSIONS

SLVs are common causative agents of acute gastroenteritis in young Finnish children. SLV disease is characterized by diarrhea, which is usually mild but can be severe. By an unknown mechanism rotavirus vaccine seems to reduce the severity of SLV-associated diarrhea.

Human caliciviruses in acute gastroenteritis of young children in the community

Episodes of acute gastroenteritis in prospectively followed children between 2 months and 2 years of age were examined for rotaviruses, enteric adenoviruses, astroviruses, and human caliciviruses, including both Norwalk-like viruses (NLVs) and Sapporo-like viruses (SLVs), using PCR and reverse transcription (RT)-PCR assays. A virus was identified in 60% (502/832) of all episodes and in 85% of the moderately severe or severe episodes. Human caliciviruses were as common as rotaviruses, both being detected in 29% of the cases. NLVs accounted for a 20% etiologic share of all cases; the clinical picture was a moderately severe disease with vomiting as a predominant symptom. SLVs were detected in 9% of the cases, the clinical picture being a mild diarrheal disease. Astroviruses were found in 10% and enteric adenoviruses in 6% of the cases. Diagnosis with PCR and RT-PCR methods increases the detection of all gastroenteritis viruses, particularly human caliciviruses. As a group, human caliciviruses are common causative agents of gastroenteritis in children <2 years of age in Finland, and, of these, NLVs cause more severe disease than SLVs.