Serotypes and electropherotypes of human rotavirus in the USA: 1987-1989

Diversity of Rotavirus Strains in Children; Results From a Community-Based Study in Nepal

Objective: The objectives of this study were to describe the incidence and genetic diversity of Rotavirus (RV) infection among children up to 3 years of age in a community in Nepal.

Methods: We investigated community-acquired cases of asymptomatic and symptomatic RV infections in children from birth to 36 months of age in a community-based birth cohort in Bhaktapur, Nepal. Monthly surveillance and diarrheal stool samples were collected from 240 children enrolled at birth, of which 238 completed the 3 years of follow-up. Samples were screened for rotavirus by Enzyme Immuno Assay (EIA). All RV screened positives were further genotyped by reverse transcription-polymerase chain reaction for the capsid genes VP7 and VP4.

Results: In total, 5,224 stool samples were collected from 238 children, followed from birth to 36 months of age. Diarrhea occurred in 92.4% (230/238) of all children in the cohort. During the 3 years study period, RV was more frequently seen in children with symptoms (7.6%) than in non-symptomatic children (0.8%). The highest RV detection rate was found in younger children between 3 and 21 months of age. Although rotavirus is known as winter diarrhea, it was detected throughout the year except in August. The highest positivity rate was observed in the months between December and March, with a peak in January. Four common G types were seen: G2 (30%), G1 (29%), G12 (19%), and G9 (16%). The most predominant genotypes seen were G2P[4] (30%), followed by G1P[8] (27.0%), G12P[6] (14.0%), G9P[8] (10%), and remaining were mixed, partial, and untyped.

Conclusion: Our study confirms that rotavirus is a common cause of gastroenteritis in young children in the community. The prevalence and pathogenicity of rotavirus infection differed by age. There was substantial variability in circulating strains in the community samples compared to samples collected from hospitals. This shows the importance of including community-based surveillance systems to monitor the diversity of circulating rotavirus strains in Nepal.

Divergence of group a rotavirus with genetic variations before and after introduction of rotavirus vaccines in northern Taiwan

Despite the development of vaccines in 2006, rotavirus is still a major cause of acute gastroenteritis worldwide. This study was performed to analyze the presence of circulating rotaviruses before and after the introduction of rotavirus vaccines to allow phylogenetic comparisons of vaccine strains in northern Taiwan.Rotavirus genotyping and sequencing of rotavirus VP7 and VP4 PCR products were performed by Reverse Transcriptase Polymerase Chain Reaction and DNA autosequencing. Phylogenies were constructed by the neighbor-joining and maximum-likelihood methods using CLUSTAL W software included in the MEGA software package (version 6.0).Between April 2004 and December 2012, a total of 101 rotavirus specimens from pediatric patients with acute gastroenteritis hospitalized in Chang Gung Children's Hospital were amplified, and their VP4 and VP7 sequences were determined. These 101 specimens consisted of 55 pre-vaccine strains (G1 [13, 23.6%], G2 [12, 21.8%], G3 [16, 29.1%], and G9 [14, 25.5%]) and 46 post-vaccine strains (G1 [25, 54.3%], G2 [12, 26.1%], G3 [5, 10.9%], and G9 [4, 8.7%]). The most common combination of the G and P types was G2P[4], accounting for 36% cases, followed by G9P[8] (25%), G1P[8] (20%), G3P[4] (15%), G3P[8] (10%), G1P[4] (5%), and G2P[8] (5%). Phylogenetic analysis showed that only the G1 and P[8] genotypes clustered in the same lineages with the rotavirus vaccine strains.Based on our results, the inclusion of G9, modified G2 and G3 with target lineages, and the combination G2P[4] and G9P[8] in the rotavirus vaccines in Taiwan is warranted as a vaccination strategy.

Molecular epidemiology and associated risk factors of rotavirus infection among children < 5 yrs hospitalized for acute gastroenteritis in North Eastern, Kenya, 2012

INTRODUCTION

Rotavirus is a leading cause of morbidity and mortality among children under five years worldwide. This study aimed to characterize the circulating genotypes of rotavirus and to determine risk factors of rotavirus infection in North Eastern, Kenya before the introduction of rotavirus vaccines.

METHODS

we conducted a cross sectional study among children < 5 years old hospitalized for acute gastroenteritis at the study hospital. Rotavirus was detected in stool specimens and further characterized using PAGE and RT-PCR. Socio-demographic and risk factor information was collected using a standard questionnaire.

RESULTS

we enrolled 237 children into the study hospitalized with acute gastroenteritis. Of these, 41 (17%) tested positive for group A rotavirus in stool specimens. Age < 2 years, unboiled tap water, underweight and low birth weight were identified as independent risk factors of rotavirus infection. Majority 8 (57%) of the detected rotavirus RNA profiles were long electropherotypes. G3, G9 and P4 were the predominant genotypes identified.

CONCLUSION

Rotavirus is an important aetiology of acute gastroenteritis among children under five years in this region. Risk factors common in other regions and rotavirus vaccine preventable genotypes are responsible for infection. We recommend the introduction of rotavirus vaccines, coupled with good infant nutrition, safe water supply and maternal hygienic practices during infant feeding.

Group A rotavirus genotypes in hospital-acquired gastroenteritis in Italy, 2012-14

BACKGROUND

Group A rotaviruses (RVA) are the leading cause of acute gastroenteritis (AGE) in young (aged <5 years) children, causing ∼250,000 deaths worldwide, mostly in developing countries. Differences on nucleotide sequences of VP7 (G-type) and VP4 (P-type) genes are the basis for the binary RVA nomenclature. Although at least 32 G-types and 47 P-types of rotavirus are presently known, most RVA infections in humans worldwide are related to five major G/P combinations: G1P[8], G2P[4], G3P[8], G4P[8], and G9P[8].

AIM

To provide the hospitals of the Italian surveillance network with update information on RVA AGE.

METHODS

During RVA gastroenteritis surveillance in Italy in 2012-14, a total of 2341 RVA-positive faecal samples were collected from children hospitalized with AGE, and RVA strains were genotyped following standard EuroRotaNet protocols.

FINDINGS

Most strains analysed belonged to the five major human genotypes and 118 out of 2341 (5.0%) were reported to be hospital-acquired. Comparison of the distributions of the RVA genotypes circulating in the community or associated with nosocomial infections showed a different distribution of genotypes circulating inside the hospital wards, with respect to those observed in the community. G1P[8] and G9P[8] RVA strains were detected frequently, whereas G12P[8] caused a single large nosocomial outbreak.

CONCLUSION

The information from this study will be useful to implement guidelines for preventing RVA AGE and optimizing the management of patients in hospital wards.

Evaluation of BBL™ Sensi-Discs™ and FTA® cards as sampling devices for detection of rotavirus in stool samples

Rotavirus is the most important cause of severe childhood gastroenteritis worldwide. Rotavirus vaccines are available and rotavirus surveillance is carried out to assess vaccination impact. In surveillance studies, stool samples are stored typically at 4°C or frozen to maintain sample quality. Uninterrupted cold storage is a problem in developing countries because of power interruptions. Cold-chain transportation of samples from collection sites to testing laboratories is costly. In this study, we evaluated the use of BBL™ Sensi-Discs™ and FTA(®) cards for storage and transportation of samples for virus isolation, EIA, and RT-PCR testing. Infectious rotavirus was recovered after 30 days of storage on Sensi-Discs™ at room temperature. We were able to genotype 98-99% of samples stored on Sensi-Discs™ and FTA(®) cards at temperatures ranging from -80°C to 37°C up to 180 days. A field sampling test using samples prepared and shipped from Cameroon, showed that both matrices yielded 100% genotyping success compared with whole stool and Sensi-Discs™ demonstrated 95% concordance with whole stool in EIA testing. The utilization of BBL™ Sensi-Discs™ and FTA(®) cards for stool sample storage and shipment has the potential to have great impact on global public health by facilitating surveillance and epidemiological investigations of rotavirus strains worldwide at a reduced cost.

Effectiveness of rotavirus vaccine in preventing hospitalization due to rotavirus gastroenteritis in young children in Connecticut, USA

Rotavirus vaccine was recommended for use in US infants to prevent rotavirus gastroenteritis (RGE) in February 2006. This matched case control study assessed the effectiveness of rotavirus vaccine in preventing hospitalization of young. Cases were vaccine-eligible children 8 weeks-3 years of age, hospitalized due to laboratory-confirmed RGE. Cases (n=42) were matched to 2 control groups: (a) hospitalized controls (n=80): children hospitalized for reasons other than RGE, matched to the cases by age and time of presentation and (b) community controls (n=73): non-hospitalized children matched by age and medical practice. Adjusted vaccine effectiveness against hospitalization with RGE in vaccine eligible children receiving at least one dose of vaccine was 94.3% (95% C.I.: 55.4%-99.3%; p=0.006) for hospitalized controls and 96.9% (95% C.I.: 59.4%-99.8%; p=0.008) for community controls.

Unexpectedly high burden of rotavirus gastroenteritis in very young infants

BACKGROUND

The highest incidence of rotavirus gastroenteritis has generally been reported in children 6-24 months of age. Young infants are thought to be partially protected by maternal antibodies acquired transplacentally or via breast milk. The purpose of our study was to assess the age distribution of children with confirmed community-acquired rotavirus gastroenteritis presenting to an urban referral hospital.

METHODS

Children presenting to The Children's Hospital of Philadelphia with acute gastroenteritis have been monitored for the presence of rotavirus antigen in the stool by ELISA (followed by genotyping if ELISA-positive) since the 1994-95 epidemic season.

RESULTS

Over the last 12 rotavirus seasons prior to the introduction of the pentavalent rotavirus vaccine in 2006, stool specimens from 1646 patients tested positive for community-acquired rotavirus infection. Gender or age was not recorded in 6 and 5 cases, respectively. Overall, 58% of the cases occurred in boys. G1 was the predominant VP7 serotype, accounting for 72% of cases. The median (IQR) age was 11 (5-21) months. A total of 790 (48%) cases occurred in children outside the commonly quoted peak age range, with 27% in infants <6 months of age and 21% in children >24 months of age. A total of 220 (13%) cases occurred during the first 3 months of life, and the highest number of episodes per month of age [97 (6%)] was observed during the second month of life.

CONCLUSIONS

The incidence of community-acquired rotavirus gastroenteritis monitored over 12 seasons in the prevaccine era at a major university hospital was nearly constant for each month of age during the first year of life, revealing an unexpectedly high incidence of symptomatic rotavirus disease in infants <3 months old. A sizeable fraction of cases occurred in children too young to have been vaccinated according to current recommendations.

Development and characterization of candidate rotavirus vaccine strains derived from children with diarrhoea in Vietnam

In Vietnam, rotavirus infection accounts for more than one-half of all hospitalizations for diarrhoea among children less than 5 years of age. While new vaccines to prevent rotavirus diarrhoea have been developed and introduced into some countries by multinational manufacturers, the ability for developing countries such as Vietnam to introduce several new and important vaccines into the routine infant immunization schedule may be challenging. In order to be partially self-sufficient in vaccine production, Vietnam has pursued the development of several rotavirus strains as candidate vaccines using isolates obtained from Vietnamese children with diarrhoea. This paper describes the origin, isolation and characterization of 3 human rotavirus strains being considered for further vaccine development in Vietnam. The goal is to prepare a monovalent G1P [8] rotavirus vaccine using one of these strains obtained in Vietnam and naturally attenuated by multiple passages in cell culture. While this is an ambitious project that will require several years' work, we are using the lessons learned to improve the overall quality of vaccine production including the use of Vero cell techniques for the manufacture of other vaccines in Vietnam.

Detection and genotyping of human rotavirus VP4 and VP7 genes by reverse transcriptase PCR and reverse hybridization

Rotavirus infections can be diagnosed in stool samples by serological and molecular methods. We developed a novel reverse transcriptase PCR (RT-PCR) method for the amplification of rotavirus RNA and a reverse hybridization assay on a strip to detect amplimers and identify the specific G and P genotypes present in human stool specimens. An additional aim was to permit specific identification of the rotavirus G1P[8] strain, used in the Rotarix vaccine. Novel broad-spectrum PCR primers were developed for both VP4 and VP7, permitting the amplification of a wide range of rotavirus genotypes. Primer sets comprise mixtures of defined primer sequences. For the identification of G and P genotypes, two reverse hybridization strip assays were developed. Both the VP4 and the VP7 strip contain universal probes for the detection of VP4 and VP7 sequences, irrespective of the G or P genotype. The VP4 strip contains type-specific probes for P[4], P[6], P[8], P[9], and P[10]. The VP7 strip contains type-specific probes for G1, G2, G3, G4, G5, G6, G8, and G9. In addition, probes to distinguish between wild-type G1 and G1 vaccine strain sequences were present. Testing by analysis of multiple reference strains confirmed that both RT-PCR methods allowed the detection of a broad spectrum of genotypes. RT-PCR for VP7 was more sensitive than RT-PCR for VP4, but all samples identified as positive for rotavirus antigen by an enzyme-linked immunosorbent assay (ELISA) were also positive for both VP4 and VP7. The high specificity of the reverse hybridization method was confirmed by sequence analysis as well as by type-specific PCR, and the vaccine strain could also be specifically identified. The reverse hybridization method permits accurate identification of mixed infections with different genotypes. Rotavirus genotypes for which no type-specific probes were present on the strip were adequately identified by the universal detection probes. The assay was formally validated by analyses of specificity, sensitivity, precision, accuracy, and robustness. In a panel of 149 ELISA-positive stool samples, comparison with conventional type-specific RT-PCR methods revealed the superiority of the novel method, mainly in cases of mixed rotavirus infections. This novel method permits highly accurate detection and identification of human rotavirus infections in stool samples. This validated assay could be useful for large-scale epidemiological and clinical trials.

Changing epidemiology of rotavirus-related hospitalizations in rio de janeiro, Brazil, from 2002 to 2006

A prospective hospital-based sentinel study conducted in Rio de Janeiro identified a shift in the pattern (long to short electropherotype and P(8) to P(4) genotype) of rotavirus strains recovered from children with severe diarrhea a few months after the far-reaching Brazilian rotavirus immunization program was launched, posing new interesting challenges.

G and P rotavirus genotypes in stool samples from children in Teresina, State of Piauí

A total of 123 stool specimens collected in Teresina, Piauí between 1994 and 1996, from 0 to 2-year-old children with diarrhea, were used for this study. Molecular characterization of the G and P rotavirus genotypes was performed using the reverse transcriptase polymerase chain reaction. The following results were obtained for the P genotypes: P[8] (17. 1%), P[1] (4. 9%), P[4] (3. 3%), P[6, M37] (2. 4%) and mixtures (27. 6%). The P[1]+P[8] mixture was found in 19. 5% of the samples. For the G genotypes, the results were: G1 (25. 2%), G5 (13. 8%), G2 (2. 5%), G4 (2. 5%), G9 (0. 8%) and mixtures (41. 5%). G1+G5 was the mixture most frequently found (12. 1%). Our results showed unusual combinations such as P[1]G5 and P[1]+P[8]G5. The high percentage of mixtures and unusual combinations containing mixtures of human and animal rotavirus genotypes strongly suggests the possibility of gene reassortment and interspecies transmission.

Characterization of rotavirus strains from hospitalized and outpatient children with acute diarrhoea in São Paulo, Brazil

From August 1994 to July 1995, 234 faecal samples from children with or without acute diarrhoea were collected and tested. The group of children with acute diarrhoea (A) was subdivided into two subgroups: subgroup A(1) was made up of children with severe diarrhoea, dehydrated and who needed hospitalization and subgroup A(2) was composed of children who only needed outpatient care. Group B was composed of children without acute diarrhoea (controls). Rotavirus was detected in 36.7% (18/49), 22.0% (15/68) and 1.7% (2/117) patients in groups A(1), A(2) and B, respectively. Of the 35 positive samples in which rotaviruses were detected the VP7 genotypes G1, G2, G3, G5 and the mixture (G2 + G5) were found in 40.0, 11.4, 11.4, 22.9 and 2.9% of the samples, respectively. Also, the VP4 genotypes P[8], P[4] and P[6] were detected in 57.1, 31.4 and 5.7%, respectively. Rotavirus VP6 subgroups I and II were detected at a frequency of 22.4 and 54.3%, respectively. Rotavirus RNA segments had short and long electrophoresis profiles in 20.0 and 51.4% of the cases, respectively. The severity of the disease was not related to a specific G and P types, subgroup or electropherotype.

1998-1999 rotavirus seasons in Juiz de Fora, Minas Gerais, Brazil: detection of an unusual G3P[4] epidemic strain

An epidemiologic survey on the rotavirus strains causing gastroenteritis in young children was conducted in Juiz de Fora, Minas Gerais, in Southern Brazil during two consecutive seasons. Rotavirus was detected in 94 of the 1,056 fecal specimens collected from January 1998 to December 1999. Among the 13 discernible long electrophoretic profiles found, one was highly prevalent (73.4%) and represented the rotavirus strain responsible for the May-August winter epidemic outbreak of 1998, as clearly shown in a three-dimensional graph. This epidemic strain, designated JF98, was characterized as subgroup II and genotype G3P[4] by the original reverse transcription-PCR typing assays. Besides the unusual combination of G and P types, this G3 strain lacked reactivity with anti-G3-specific monoclonal antibodies and presented an uncommon pattern upon digestion of its cDNA-copied VP7 gene with the BstYI restriction enzyme. Strain JF98 affected primarily 6- to 24-month-old children and accounted for 85.5% of the severe rotavirus-associated dehydrating diarrhea cases that required hospitalization. As in our previous studies in neighboring Rio de Janeiro and São Paulo, a remarkably large proportion (44%) of mixed infections was detected, generating a complex set of circulating strains in the community, represented by the many distinct electropherotypes. Other common human types were detected as minor strains in single or in mixed infections, including the JF98 strain. Those were types G1, G4, G8, G9, P[8], and P[6], but not G2 or G5. One specimen contained a mixture of group A and C rotaviruses.

Rotavirus infection and intussusception: a view from retrospect

A live orally-administrable rhesus rotavirus (RRV) tetravalent (TV) vaccine, licensed in the U.S.A. and the European Union, was recalled from the market because it was suspected to increase the risk of intussusception during the week following immunization. In contrast, natural rotavirus infection is generally believed not to cause intussusception. Because my experience contributed to the first paper that linked intussusception with rotavirus infection, I have re-examined our own data published 22 years ago and other studies on this issue. I also made a case study of adenovirus and intussusception as a paradigm to establish an etiological association of viral infection and intussusception. My hypothesis postulated in this review is that natural infection of susceptible (or predisposed) infants with some rotavirus strains, probably serotype G3 rotaviruses, will result in an appreciable fraction of idiopathic intussusception. Thus, the number of rotavirus-induced intussusception cases may change reflecting the relative frequency of G3 strains, which I believe was much higher in the 70s than during the last two decades. The epidemiological data indicate that the RRV-TV vaccine triggers intussusception at a rate significantly higher than the background incidence rate following the week of vaccination, particularly after the first dose. In contrast, the data do not suggest that the cumulative incidence among the vaccine recipients increases accordingly, implicating that the risk of intussusception attributable to the RRV-TV vaccine may be minimal.

The relative frequencies of G serotypes of rotaviruses recovered from hospitalized children with diarrhea: A 10-year survey (1987-1996) in Japan with a review of globally collected data

Since rotavirus vaccines aim to protect children from severe diarrhea, knowledge of the prevailing G serotypes among rotaviruses from hospitalized children is essential. Thus, we determined the G serotypes of rotaviruses collected from children with acute diarrhea in a local referral hospital in Akita, Japan, over the 10-year period between January 1987 and December 1996. Based on the assumption that rotaviruses with an identical electropherotype possess the same G serotype, the G serotypes of 488 rotavirus-positive specimens that were classified into 63 electropherotypes were determined by enzyme-linked immunosorbent assay with a supplementary use of G typing by reverse transcription-PCR. The relative frequencies over the 10-year period were 77.0 (G1), 14.5 (G2), 2.7 (G3) and 5.3% (G4), leaving the possibility that only 0.4% had G serotypes uncommon to human rotaviruses. Of 24,050 rotaviruses extracted by reviewing 63 serotyping studies in literature, the relative frequencies of the four major G serotypes were 50.6 (G1), 9.3 (G2), 7.2 (G3) and 11.6% (G4). As to uncommon G serotypes, only 0.9% were described as serotypes other than G1-4, and our estimate for potential uncommon serotypes were at most 8.1%. Thus, both this long-term study focusing on the rotaviruses only from severe cases in a single hospital in Japan and the global review of G serotypes published to date indicate that the primary target of any rotavirus vaccines should be rotaviruses possessing serotypes G1-4.

[Identification of rotavirus associated to serotype G2 in Yucatan, Mexico]

In the present study, rotavirus G2 serotype was identified from fecal samples of children with gastroenteritis from the city of Merida, Yucatan, Mexico. Virological diagnosis of disease was performed using polycrylamide gel electrophoresis and immunoenzymatic assay. Out of 149 analyzed samples 25 (16.7%) gave positive reaction to rotavirus groups A, of these 23 (92%) were identified as serotype g2, subgroup i and electrophoretic short pattern, whereas 2 (8%) were identified as subgroups II and electrophoretic long pattern, however, the G serotype was not possible to determine. Rotavirus G serotype has not been detected in more than 90% of samples since 1985. This indicates that the number of people susceptible to G2 serotype within the population has increased over recent years, which perhaps indicates that an important outbreak of acute infectious diarrhea caused by the rotavirus G2 serotype may be forthcoming.

Epidemiology of rotavirus infection in Thailand

Rotavirus is a major cause of acute severe diarrhea in children worldwide and an important cause of death among young children in developing countries. Group A rotaviruses are antigenically complex and multiple serotypes infect humans. Reassortant rotavirus vaccines are now available which offer protection against severe illness caused by rotavirus serotypes G1-4. Before vaccines are introduced into target populations, it is necessary to establish the baseline data of the epidemiology of rotavirus infection in those countries. The purpose of the present study is to provide information related to the epidemiology of rotavirus infection in Thailand. All rotavirus studies performed in Thailand were found through Medline and Thai Index Medicus searches. A total of 26 of the most relevant studies published in international and national journals are reviewed. Most studies reported that the prevalence of rotavirus infection in Thailand was 27-34%, although a few studies have reported a prevalence above this range. The peak seasonal distribution of rotavirus infection among children hospitalized with diarrhea in Thailand was seen in the dry cool seasons: October to February. The prevalence of rotavirus infection was most frequently found in children aged 6-11 months up to 2 years. G1 was the most prevalent serotype in Thailand, followed by G2, G4 and G3, respectively. At least three G serotypes, mostly G1, G2 and G4, are seen to coexist in Thailand each epidemic year and in some studies all four G-serotypes were reported in the same epidemics. In a 1996-1997 study, G9 was the third prevailing serotype after G1 and G2, respectively. These results indicate that rotavirus epidemics occur in Thailand every year and children are the most affected population. In Thailand, although G1-G4 have been reported, G1 is the most prevalent serotype in each epidemic and G9 is becoming increasingly common.

Surveillance of rotavirus strains in the United States: identification of unusual strains. The National Rotavirus Strain Surveillance System collaborating laboratories

Rotavirus strains from 964 fecal specimens collected from children at 11 U.S. hospital laboratories from November 1997 to March 1998 and from samples collected at 12 laboratories from November 1998 to March 1999 were typed for G and P proteins. Serotype G1 was the predominant serotype in 1997-1998 (88%), followed by G2 (6.2%), G9 (3.3%), and G3 (1.5%). This pattern was similar to that seen in 1998-1999: G1 (79%), G2 (15%), G9 (3.0%), G4 (1.6%), and G3 (0.3%). Novel P[9] strains were identified in both seasons, and analysis of a 364-nucleotide fragment from gene segment 4 of one of the strains demonstrated 97.3% nucleotide identity with the prototype P3[9],G3 strain, AU1, isolated in Japan. This is the first report of a human AU1-like strain in the United States. These results reinforce our initial findings that serotype G9 persists in the United States but has not become a predominant strain and that the common serotypes G1 to G4 account for almost 90% of strains in circulation. Other uncommon strains exist in the United States but may have been overlooked before because of their low prevalence and the use of inadequate diagnostic tools.

Detection of porcine rotavirus type G9 and of a mixture of types G1 and G5 associated with Wa-like VP4 specificity: evidence for natural human-porcine genetic reassortment

Rotavirus type G5 is a primarily porcine pathogen that has caused frequent and widespread diarrhea in children in Brazil and in piglets elsewhere. Initial results on the rotavirus types circulating in diarrheic piglets in Brazil disclosed a high diversity of strains with distinct G types including G1, G4, G5, and G9 and the novelty of P[8], the predominant human P specificity type. Those results add strong evidence for the emergence of new strains through natural reassortment between rotaviruses of human and porcine origins.

Epidemiological study of the G serotype distribution of group A rotaviruses in Kenya from 1991 to 1994

An epidemiological study on the G serotype distribution of group A rotaviruses (GARV) isolated in Kenya was carried out in one urban hospital in Nairobi and in two rural hospitals in Nanyuki and Kitui to clarify the prevalent G serotypes before future introduction of the ready licensed rotavirus vaccine in Kenya. A total of 1,431 stool specimens were collected from children, who were mainly outpatients, aged from 0 to 6 years old with acute gastroenteritis from August 1991 to July 1994. Samples positive for GARV by conventional ELISA were then analyzed by subgrouping and serotyping ELISA and by PAGE. To ascertain the G serotypes of viruses in samples that were unable to be typed by serotyping ELISA, polymerase chain reaction was also attempted. The prevalence of GARV was 28.4% in the urban hospital, 22.5% in Nanyuki, and 13.7% in Kitui. Among rotavirus-positive samples, subgroup II rotaviruses were detected in 63.1%, and subgroup I rotaviruses were 25.9%. Serotype G4 was most prevalent, accounting for 41.6% followed by 23.3% of serotype G1, 17.0% of serotype G2, and serotype G3 was rarely isolated. Seven strains of serotype G8/P1B rotavirus was detected for the first time in Kenya by RT-PCR. Eleven specimens with an unusual composition of subgroup, serotype, and electropherotype were atypical GARV in which the P-serotype was P1A, P1B, or P2. Although uncommon GARV serotype G8/P1B and atypical GARV were detected, the four major GARV serotypes, G1 through G4, should be targeted at this moment for vaccination to control this diarrheal disease in Kenya. Continuous monitoring of the G- and P-serotype distribution of GARV should provide important information about the impact of rotavirus vaccination in Kenya.

The current status of the rotavirus vaccine

The US just licensed of an oral tetravalent rhesus reassortant vaccine for routine immunization of infants against rotavirus. The virus was first identified 25 years ago and is now recognized to be the most common single cause of severe diarrhea throughout the world. Most children suffer at least one infection and reinfection is common. Studies of natural immunity show that breastfeeding may merely delay onset of primary infection and that maternal immunity has little effect-especially in developing countries where onset in early infancy is common. Immunity, furthermore, appears to be serotype-specific. Early attempts to develop a vaccine focused on animal forms of rotavirus. More recent efforts have created human-animal reassortants that have been far more successful.

Seasonality and diversity of Group A rotaviruses in Europe

Group A rotaviruses are a major cause of severe gastroenteritis in children under 4 y of age worldwide. Group A rotaviruses have been identified in many animal and bird species, they are antigenically complex, and multiple serotypes infect humans. Re-assortant rotavirus vaccines are now available which confer protection against severe illness due to rotavirus serotypes G1-4. Before vaccines are introduced it is necessary to establish the diversity of rotavirus in the target population to ensure efficacy and to establish a baseline for future surveillance strategies. The purpose of this review is to describe our current knowledge of the diversity of rotaviruses across Europe. Since multinational studies with standardized methodology have not been performed, this review is based on the available published studies. In Europe, more than 90% of Group A rotavirus strains that have been typed are of serotypes G1-4, with an average 8% of non-G1-4 strains in published studies. The percentage of non-typeable strains may fluctuate from one year to another, and has been as high as 18% in one study in Great Britain, indicating the need for a more systematic study. Group A rotavirus infection typically occurs as a winter peak in the European countries studied. Comparison of seasonality data from national laboratory surveillance systems showed seasonal differences, with the annual rotavirus peak occurring first in Spain, usually in December, followed by France in February, and ending in Northern Europe in England and Wales in February or March, and the Netherlands and Finland in March.

Prospects for vaccines against rotaviruses

Candidate vaccines against rotavirus-caused diarrhoea have been under development for more than ten years. Recent research has helped to identify virological and immunological parameters which are most likely to be correlates of protection from rotavirus infection and disease. Large double-blind, placebo-controlled trials in the United States and Venezuela have resulted in successful protection from severe disease and dehydration after immunisation with live-attenuated rhesus rotavirus-based monovalent and tetravalent vaccine candidates. The tetravalent vaccine is now submitted for regulatory approval in the United States. The anticipated widespread use of such a vaccine will need careful safety and effectiveness surveillance as the enormous diversity of rotavirus antigenicity may affect efficacy in different geographical regions. To proceed from licensure to reduction of disease a series of goals must be achieved: the vaccine must be recommended by major immunisation advisory committees, be financed in both the public and private sectors, be integrated into existing vaccination schedules, be promoted, find parental acceptance and achieve a high level of coverage. Copyright 1998 John Wiley & Sons, Ltd.

Visualizing geographic and temporal trends in rotavirus activity in the United States, 1991 to 1996. National Respiratory and Enteric Virus Surveillance System Collaborating Laboratories

BACKGROUND

Rotavirus is the leading cause of severe pediatric gastroenteritis worldwide. A vaccine may soon be licensed for use in the United States to prevent this disease. To characterize US geographic and temporal trends in rotavirus activity, we made contour maps showing the timing of peak rotavirus activity.

METHODS

From July, 1991, through June, 1996, 79 laboratories participating in the National Respiratory and Enteric Virus Surveillance System reported on a weekly basis the number of stool specimens that tested positive for rotavirus. The peak weeks in rotavirus detections from each laboratory were mapped using kriging, a modeling technique originally developed for geostatistics.

RESULTS

During the 5-year period 118,716 fecal specimens were examined, of which 27,616 (23%) were positive for rotavirus. Timing of rotavirus activity varied by geographic location in a characteristic pattern in which peak activity occurred first in the Southwest from October through December and last in the Northeast in April or May. The Northwest exhibited considerable year-to-year variability (range, December to May) in the timing of peak activity, whereas the temporal pattern in the remainder of the contiguous 48 states was relatively constant.

CONCLUSION

Kriging is a useful method for visualizing geographic and temporal trends in rotavirus activity in the United States. This analysis confirmed trends reported in previous years, and it also identified unexpected variability in the timing of peak rotavirus activity in the Northwest. The causes of the seasonal differences in rotavirus activity by region are unknown. Tracking of laboratory detections of rotavirus may provide an effective surveillance tool to assess the impact of a rotavirus vaccination campaign in the United States.

Serotype of Nigerian rotavirus strains

Three hundred and fourteen stool samples collected from children < 5 years between December 1993 and August 1995 were analysed by PAGE, ELISA, PCR and Dot-blot hybridization technique for electropherotype and serotype distribution of rotavirus infection among Nigerian paediatric patients. 14.3% of the children were positive for rotavirus antigen. Children aged 6-9 months were most often infected, accounting for 35.6% of all positive samples, 91.1% of rotavirus-positive samples could be serotyped. Serotypes G2, G4 and G8 were not detected. Serotype G3 predominated (62.5%) in southern Nigeria, while mixed infection specificity was more widespread (63.6%) in northern Nigeria. The presence of some untypeable samples may indicate serotypes which the serotype-specific primers and cDNA probes used could not detect. Electropherotypes of 26 (57.7%) of the positive samples were determined. Two and 3 migration patterns were observed among the short and long-pattern electropherotypes, respectively. Implications for vaccine development and utilization in the country are discussed.

Rotavirus serotypes and electropherotypes in Finland from 1986 to 1990

Four epidemic seasons of rotaviruses were studied in Helsinki during 1986-1990. This is the first Scandinavian study, where both electropherotypes and serotypes are determined. Out of 5316 fecal specimens 769 (14.5%) rotavirus positive samples were detected by electron microscopy. Of these, 645 isolates (83.9%) gave a clear RNA pattern in gel electrophoresis and they clustered into 87 electropherotypes. An illustrative number of isolates representing each electropherotype (= E-type) was serotyped using VP7 protein-specific monoclonal antibodies for serotypes G1-G4 and without exceptions, within one E-type only a single serotype specificity was found. After establishment of the serotype of each E-type, the distribution of serotypes was scored as 61.2%, 2.0%, 0.5% and 29.8% for G1-G4, respectively; 6.5% remained untypable. Two seasons had one predominant E-type (Season 1, 1986-87, and Season 3, 1988-89, 84.2% and 80.6% of rotavirus positive samples, respectively). Both were followed by a season with no predominant E-type, but several minor E-types. Altogether, 5 short E-types (13/645 samples) with serotype G2 specificity were found, most of them occurring in Season 2. Only 2 E-types (3 samples) belonged to serotype G3. Group C rotavirus was found in 8 specimens. In this study a shift in serotypes, from G1 to G4, was observed in Finland in 1988/89; a similar shift was reported in many European countries at that time.

Survey of rotavirus G and P types associated with human gastroenteritis in São Paulo, Brazil, from 1986 to 1992

Rotavirus strains causing gastroenteritis in Brazilian children were characterized by PCR-based typing assays. In addition to strains bearing the major human G and P types, large numbers of strains bearing P3 (M37-like), P6 (HCR3-like), untypeable P and G types, and complex mixtures of P and G types not previously recognized were present in the community.

Rotavirus serotypes causing severe acute diarrhea in young children in six Australian cities, 1989 to 1992

Rotavirus VP7 serotypes were identified in stools from 72.9% (1,302/1,784) of hospitalized Australian children in six cities (1989 to 1992) and comprised 1,088 (83.6%) serotype G1 isolates, 84 (6.4%) serotype G2 isolates, 64 (4.9%) serotype G3 isolates, 49 (3.8%) serotype G4 isolates, and 17 (1.3%) isolates of mixed serotypes. The most densely populated cities yielded the greatest diversity of serotypes.

Electropherotypes and serotypes of human rotavirus in Estonia in 1989-1992

The electropherotypes and serotypes of human rotaviruses circulating in Tallinn (Estonia) in 1989-1992 have been studied. Rotaviruses were found in 372 (25.8%) of 1,442 faecal specimens of pediatric patients with acute diarrhea. Polyacrylamide gel electrophoresis of RNA from 318 isolates has revealed 41 electropherotypes. Frequent genomic alterations, including a shift of predominant electropherotypes, were observed during the study period. The serotype of 158 (50.3%) of 314 tested rotavirus isolates was identified using ELISA with VP7-specific monoclonal antibodies against 4 established human rotavirus serotypes. Serotype G1 was found to be largely predominant and accounted for 70.9% of the typeable specimens, serotypes G4, G2, and G3 accounted for 12%, 9.5%, 7.6%, respectively. A major shift to serotype G4 took place in 1990-1991. Serotype G1 was represented by the largest number of electropherotypes. All G1, G3 and G4 isolates were of "long" and all G2 isolates were of "short" electropherotypes. According to our results the isolates of an identical electropherotype belong to the same serotype.

Improved method for purification of viral RNA from fecal specimens for rotavirus detection

An improved procedure to recover and purify double-stranded RNA (dsRNA) from fecal specimens is described. Guanidine isothiocyanate, hydroxyapatite, and cetyltrimethylammonium bromide were used to extract and purify rotavirus dsRNA from fecal specimens. The method is very efficient and easy to perform, and precludes the use of toxic substances such as phenol, chloroform, and Freon. It yields RNA free of enzymatic inhibitors, permitting its detection by reverse transcription-polymerase chain reaction assays. In addition, it was demonstrated that during initial clarification of the fecal suspension, the pellet must be washed at least twice to avoid massive losses of virus, viral protein, or viral nucleic acid retained in the solid debris.

VP4 genotyping of human rotavirus in the United States

The VP4 (P) and VP7 (G) types of 171 rotavirus isolates obtained from children with diarrhea in the United States were characterized by PCR typing assays. Strains P1G1 predominated (71%); this was followed by strains P1G3 (20%) and P2G2 and P1G4 (2% each). Mixed types were identified in five (3%) specimens. Two (1%) strains bearing the P3 genotype (P3G1 and P3G2) were found in children with severe dehydrating diarrhea, although the P3 genotype has been regarded as a possible marker for virus attenuation.

Rotavirus vaccines and vaccination potential

The development of a successful rotavirus vaccine is a complex problem. Our review of rotavirus vaccine development shows that many challenges remain, and priorities for future studies need to be established. For example, the evaluation of administration of a vaccine with OPV or breast milk might receive less emphasis until a vaccine is made that shows clear efficacy against all virus serotypes. Samples remaining from previous trials should be analyzed to determine epitope-specific serum and coproantibody responses to clarify why only some trials were successful. Detailed evaluation of the antigenic properties of the viruses circulating and causing illness in vaccinated children also should be performed for comparisons with the vaccine strains. In future trials, sample collection should include monitoring for asymptomatic infections and cellular immune responses should be analyzed. The diversity of rotavirus serotype distribution must be monitored before, during, and after a trial in the study population and placebo recipients must be matched carefully to vaccine recipients. Epidemiologic and molecular studies should be expanded to document, or disprove, the possibility of animal to human rotavirus transmission, because, if this occurs, vaccine protection may be more difficult in those areas of the world where cohabitation with animals occurs. We also need to have an accurate assessment of the rate of protection that follows natural infections. Is it realistic to try to achieve 90% protective efficacy with a vaccine if natural infections with these enteric pathogens only provide 60% or 70% protection? Subunit vaccines should be considered to be part of vaccine strategies, especially if maternal antibody interferes with the take of live vaccines. The constraints on development of new vaccines are not likely to come from molecular biology. The challenge remains whether the biology and immunology of rotavirus infections can be understood and exploited to permit effective vaccination. Recent advances in developing small animal models for evaluation of vaccine efficacy should facilitate future vaccine development and understanding of the protective immune response(s) (Ward et al. 1990b; Conner et al. 1993).

Diarrhoeal disease: current concepts and future challenges. Epidemiology of diarrhoeal diseases in developed countries

Diarrhoeal diseases are a common problem in industrialized countries, resulting in appreciable morbidity and mortality. While the total burden of these illnesses is much less than that in developing countries, the same basic disease risk factors influence transmission. This article reviews selected environmental, host and pathogen-specific factors which shape the epidemiology of infectious diarrhoea in developed countries. The effective adaptation of techniques from molecular biology, such as plasmid analysis, deoxyribonucleic acid hybridization, and the polymerase chain reaction, to studies of diarrhoeal disease epidemiology is also discussed.

Serotype analysis of rotaviruses from different locations in Malaysia

The distribution of rotavirus G (VP7) serotypes circulating in four locations in Malaysia, representing three geographical areas, was evaluated in 341 RNA-positive stool specimens obtained discontinuously between 1977 and 1988 from infants and young children under the age of five years who were hospitalized with acute gastroenteritis. A total of 306 specimens (256 stool suspensions and 50 that were adapted to growth in tissue culture) that were rotavirus positive by the confirmatory enzyme-linked immunosorbent assay (ELISA) were examined for serotype by ELISA utilizing monoclonal antibodies to rotavirus G serotype 1, 2, 3, 4, or 9. One hundred eighty (59%) of the 306 specimens could be serotyped; of these 180 specimens, 71% were serotype 4, 15% were serotype 1, 4% were serotype 2, and 4% were serotype 3. Serotype 9 rotavirus was not detected. Most (71%) of the specimens tested were obtained in 1988, when serotype 4 predominated in three locations in West Malaysia; no single serotype was predominant in a limited number of specimens from East Malaysia.

Restriction endonuclease analysis of the vp7 genes of human and animal rotaviruses

The vp7 genes of 194 strains of group A rotaviruses representing all known G types were analyzed with three restriction enzymes by direct digestion of amplified cDNA copies or by deduction of the restriction patterns from known sequences. Mammalian rotavirus strains were classified into 28 restriction patterns consisting of combinations of the 6 profiles (s1 to s6) obtained by digestion with Sau96I endonuclease, 9 profiles (h1 to h9) obtained with HaeIII, and 15 profiles (b1 to b15) obtained with BstYI. Digestion with Sau96I and HaeIII identified restriction sites common to all, or almost all, rotavirus strains studied, whereas BstYI was the most discriminating among rotavirus strains. A clear correlation between some restriction patterns or individual profiles and G type and/or host species of origin was found. Several discriminatory restriction sites consisted of type-specific nucleic acid sequences that encoded conserved amino acid residues. Although not directly involved in antigenic diversity, these sites appear to indicate the G type of the isolate. The technique permits rapid comparison of a large number of virus isolates directly from fecal specimens and provides useful markers for investigating the evolution of rotavirus vp7 genes and tracing vaccine virus and interspecies transmission.

Rotavirus diarrhea in Bangladeshi children: correlation of disease severity with serotypes

To improve the understanding of the relative importance of serotypes of rotavirus in dehydrating diarrhea, we examined the correlation of clinical characteristics and disease severity with serotype in 2,441 diarrheal episodes among children younger than 2 years of age in rural Bangladesh. Of 764 rotavirus-associated episodes, a single G type (serotype 1, 2, 3, or 4) was determined by oligonucleotide probe in 485 (63%), while 233 episodes were nontypeable. Episodes with G types 2 and 3 were associated with more-severe dehydration than episodes associated with G type 1 or 4 or with nontypeable rotavirus. Episodes did not differ by G type in prevalence of vomiting, copious diarrhea, fever, abdominal pain, or length of treatment center stay. Rotavirus reinfections were detected in seven children, with homologous reinfection (G type 2) in one. Twelve children with diarrhea who died had rotavirus detected in stool specimens within 30 days of death. Children who died were more likely to be malnourished than were surviving children with rotavirus diarrhea. Of 40 specimens tested by polymerase chain reaction, 29 (72.5%) were P type 1, 9 (22.5%) were P type 2, 1 (2.5%) was P type 3, and 1 (2.5%) was nontypeable. One severely symptomatic diarrheal episode was associated with P type 3 rotavirus, a serotype usually found in asymptomatic nursery infections. Although G types 2 and 3 were associated with more-severe dehydration than other serotypes, the differences do not appear to be of major clinical importance. Effective vaccines should protect against all four major G types.

A family outbreak of gastroenteritis caused by group C rotavirus

A family outbreak of gastroenteritis caused by group C rotavirus is described. All five members of the family, with children between 8 and 15 years of age, fell ill with diarrhea. The diagnosis was initially based on the detection of rotavirus RNA showing a typical group C profile in gel electrophoresis in stool samples, and it was serologically verified from patient sera using a cell culture adapted porcine group C rotavirus as a source of standard antigen. All collected serum samples from the family contained IgM and/or IgG class antibodies to group C rotavirus measurable by immunofluorescence antibody test (IFAT). Group C rotavirus specific IgM class antibodies were present in the early serum samples in 3/4 patients. A roller tube neutralization test (NT) was established to demonstrate neutralizing antibodies to porcine group C rotavirus in human sera. These methods can be used to detect serologically group C rotavirus infections.

Serotype variation of group A rotaviruses over nine winter epidemics in southeastern New England

By the use of enzyme immunoassay and RNA electrophoresis, rotavirus serotyping was performed with stool specimens from 605 children. Serotypes 1, 2, 3, and 4 accounted for 63, 9, 9, and 19% of the cases, respectively, with considerable yearly variation. An average of three serotypes cocirculated each year.

Distribution of serotypes of human rotavirus in different populations

Serotyping is a useful tool to study the epidemiologic characteristics of rotaviruses in large populations and to assess the need for a vaccine to protect against all strains. By using an enzyme immunoassay with serotype-specific monoclonal antibodies to the four most common rotavirus serotypes, we analyzed 1,183 rotavirus-positive specimens from 16 stool collections in eight countries on four continents that were obtained from 1978 to 1989. Of the 926 strains (78%) that could be serotyped, 48% were serotype 1, 8% were serotype 2, 15% were serotype 3, and 7% were serotype 4. Twenty-two percent had insufficient numbers of double-shelled virus particles to react with the monoclonal antibody of the VP4 rotavirus protein and therefore could not be serotyped. Our results indicate that vaccines being developed must provide the greatest coverage against serotype 1 and that the serotype distribution cannot be predicted currently by the geographic area or prevalence in the preceding year.

Comparisons of rotavirus VP7-typing monoclonal antibodies by competition binding assay

Three sets of neutralizing monoclonal antibodies (MAbs) used to type the outer capsid protein VP7 of four group A rotavirus serotypes (1 through 4) were compared in competition immunoassays. Reciprocal competition was observed for each of the VP7 type 2-, 3-, and 4-specific MAbs. The VP7 type 1 MAbs exhibited variable competition patterns with other VP7 type 1 MAbs. MAb RV4:3, which has been used to recognize antigenic variants within VP7 type 1 strains, showed reciprocal competition with the four VP7 type 3 MAbs (RV3:1, YO-1E2, 4F8, and 159) using a VP7 type 3 virus (SA11) as antigen. MAb 2C9, also prepared against VP7 type 1, reacted with VP7 type 3 strains and competed with a VP7 type 3 MAb, 159, using RRV as antigen. Use of the different sets of VP7 type-specific MAbs in the enzyme-linked immunosorbent assay permitted the recognition of six antigenic variants within VP7 types 1, 2, and 3 among specimens whose VP7 type could not be determined previously with only one set of typing MAbs. These results demonstrate differences of typing ability among these VP7-specific MAbs and emphasize the need to improve the sensitivity of typing systems by incorporating panels of MAbs reacting with several neutralizing epitopes.

Human and bovine serotype G8 rotaviruses may be derived by reassortment

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