Characterisation of rotavirus G9 strains isolated in the UK between 1995 and 1998

Antigenic epitope analysis of Pakistani G3 and G9 rotavirus strains compared to vaccine strains revealed multiple amino acid differences

Rotaviruses belong to genotype VP4-P[8] are a significant cause of severe loose diarrhea in infants and young children. In the present study, we characterised the complete genome of three of the Pakistani P[8]b RVA strains by Illumina HiSeq sequencing technology to determine the complete genotype constellation providing insight into the evolutionary dynamics of their genes using maximum likelihood analysis. The maximum genomic sequences of our study strains were similar to more recent human Wa-Like G1P[8]a, G3P[8]a, G4P[6], G4P[8], G9P[4], G9P[8]a, G11P[25],G12P[8]a and G12P[6] strains circulating around the world. Therefore, strains PAK274, PAK439 and PAK624 carry natively distinctive VP4 gene with universally common human Wa-Like genetic backbone. Comparing our study P[8]b strains with vaccines strains RotarixTM and RotaTeqTM, multiple amino acid differences were examined between vaccine virus antigenic epitopes and Pakistani isolates. Over time, these differences may result in the selection for strains that will escape the vaccine-induced RVA-neutralizing-antibody effect.

Epidemiological significance of the occurrence and persistence of rotaviruses in water and sewage: a critical review and proposal for routine microbiological monitoring

Globally, waterborne gastroenteritis attributable to rotaviruses is on the increase due to the rapid increase in population growth, poor socioeconomic conditions, and drastic changes in climatic conditions. The burden of diarrhea is quite alarming in developing nations where the majority of the populations still rely on untreated surface water that is usually polluted for their immediate water needs. Humans and animals of all ages are affected by rotaviruses. In humans, the preponderance of cases occurs in children under 5 years. Global efforts in advancing water/wastewater treatment technologies have not yet realized the objective of complete viral removal from wastewater. Most times, surface waters are impacted heavily by inadequately treated wastewater run-offs thereby exposing people or animals to preventable health risks. The relative stability of rotaviruses in aquatic matrices during wastewater treatment, poor correlation of bacteriological indicators with the presence of rotaviruses, and their infectiousness at a low dose informed the proposal for inclusion in the routine microbiological water screening panel. Environmental monitoring data have been shown to provide early warnings that can complement clinical data used to monitor the impact of current rotavirus vaccination in a community. This review was therefore undertaken to critically appraise rotavirus excretion and emission pathways, and the existence, viability and persistence in the receiving aquatic milieu. The efficiency of the current wastewater treatment modality for rotavirus removal, correlation of the current bacteriological water quality assessment strategy, public health risks and current laboratory methods for an epidemiological study were also discussed.

Predominance of new G9P[8] rotaviruses closely related to Turkish strains in Nizhny Novgorod (Russia)

Genotype G9P[8] rotaviruses are rare in the territory of Russia. They were found in Nizhny Novgorod only in 2011-2012 for the first time, when their proportion was 25.9%. During the next two seasons, G9P[8] strains were detected in only 1.8% of cases. Their proportion substantially increased again in 2014, and they became predominant in the city by 2016. Phylogenetic analysis on the basis of gene VP7 nucleotide sequences showed that this increase was accompanied by the emergence of new strains in the population. These isolates were related to Turkish strains, but not to Russian ones detected earlier.

Great genetic diversity of rotaviruses detected in piglets with diarrhea in Thailand

A total of 491 fecal specimens collected from diarrheic piglets in Thailand from January 2011 to March 2014 were screened for group A rotavirus by RT-PCR assay. The G and P genotypes of the detected rotaviruses were determined by multiplex PCR or nucleotide sequencing. Group A rotaviruses were detected in 113 out of 491 (23.0 %) fecal specimens. A wide variety of G-P genotype combinations were identified, and G4P[13] was the most prevalent genotype combination (29.2 %), followed by G4P[23] (14.1 %), G5P[23] (11.5 %), G4P[6] (9.7 %), G3P[23] (7.0 %), G5P[13] (6.1 %), G3P[13] (4.4 %), G3P[6] (2.7 %), and G5P[6] (2.7 %). In addition, the other G-P combinations were also detected at a low percentage, including G3P[19], G4P[7], G9P[19], G9P[23], G9P[7], G4P[19], and G11P[13] strains. This study indicated that group A rotaviruses are a common causes of diarrhea in piglets and a great diversity of G and P genotype combinations are circulating in piglets in Thailand.

Genetic diversity of porcine group A rotavirus strains in the UK

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This is the first study of rotavirus genotypes circulating in UK pigs.

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Rotavirus transmission between pigs and humans is not thought to be common in the UK.

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Human rotavirus genotype P[8] found in a UK pig.

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The uncommon rotavirus genotype P[32] is widespread in UK pig herds.

Rotavirus is endemic in pig farms where it causes a loss in production. This study is the first to characterise porcine rotavirus circulating in UK pigs. Samples from diarrheic pigs with rotavirus enteritis obtained between 2010 and 2012 were genotyped in order to determine the diversity of group A rotavirus (GARV) in UK pigs. A wide range of rotavirus genotypes were identified in UK pigs: six G types (VP7); G2, G3, G4, G5, G9 and G11 and six P types (VP4); P[6], P[7], P[8], P[13], P[23], and P[32]. With the exception of a single P[8] isolate, there was less than 95% nucleotide identity between sequences from this study and any available rotavirus sequences.

The G9 and P[6] genotypes are capable of infecting both humans and pigs, but showed no species cross-over within the UK as they were shown to be genetically distinct, which suggested zoonotic transmission is rare within the UK. We identified the P[8] genotype in one isolate, this genotype is almost exclusively found in humans. The P[8] was linked to a human Irish rotavirus isolate in the same year. The discovery of human genotype P[8] rotavirus in a UK pig confirms this common human genotype can infect pigs and also highlights the necessity of surveillance of porcine rotavirus genotypes to safeguard human as well as porcine health.

Molecular characterization of rotavirus strains from pre- and post-vaccination periods in a country with low vaccination coverage: the case of Slovenia

Rotavirus vaccination started in Slovenia in 2007 on a voluntarily basis. The vaccination rate is relatively low (up to 27%) and no increasing trend is observed. We present rotavirus genotype distribution among children hospitalized for rotavirus gastroenteritis in Slovenia. Eight consecutive rotavirus seasons were followed, from 2005/06 to 2012/13, and 113 strains of the most common rotavirus genotypes were randomly selected for molecular characterization of rotavirus VP7 and VP4 (VP8(∗)) genome segments. During the vaccine introduction period, from 2007 to 2013, rotavirus genotype prevalences changed, with G1P[8] decreasing from 74.1% to 8.7% between 2007/08 and 2010/11 seasons, replaced by G4P[8] and G2P[4], with up to 52.0% prevalence. Comparable analysis of VP7 and VP8(∗) genome fragments within G1P[8] genotype lineages revealed considerable differences for rotavirus strains circulating before and during the vaccination period. The G1P[8] rotavirus strains from the pre-vaccination period clustered in a phylogenetic tree within Rotarix®-like VP7 and VP8(∗) lineages. However, since 2007, the majority of G1P[8] strains have shifted to distant genetic lineages with lower nucleotide (88.1-94.0% for VP7 and 86.6-91.1% for VP8(∗)) and amino acid (93.8-95.2% for VP7 and 85.3-94.6% for VP8(∗)) identities to the vaccine Rotarix® strain. This change also resulted in a different deduced amino acid profile at the major VP7 and VP8(∗) antigenic epitopes.

Rotaviruses: is their surveillance needed?

Rotaviruses, a major cause of gastroenteritis in children worldwide accounts for around 0.5 million deaths annually. Owing to their segmented genome and frequently evolving capability, these display a wide variation in their genotypes. In addition to commonly circulating genotypes (G1, G2, G3, G4, G9, P[4] and P[8]), a number of infrequent genotypes are being continuously reported to infect humans. These viral strains exhibit variation from one geographical setting to another in their distribution. Though the introduction of vaccines (RotaTeq and Rotarix) proved to be very effective in declining rotavirus associated morbidity and mortality, the number of infections remained same. Unusual genotypes significantly contribute to the rotavirus associated diarrhoeal burden, may reduce the efficacy of the vaccines in use and hence vaccinated individuals may not be benefited. Vaccine introduction may bring about a notable impact on the distribution and prevalence of these viruses due to selection pressure. Moreover, there is a sudden emergence of G2 and G3 in Brazil and United States, respectively, during the years 2006-2008 post-vaccination introduction; G9 and G12 became predominant during the years 1986 through 1998 before the vaccine introduction and now are commonly prevalent strains; and disparity in the predominance of strains after introduction of vaccines and their natural fluctuations poses a vital question on the impact of vaccines on rotavirus strain circulation. This interplay between vaccines and rotavirus strains is yet to be explored, but it certainly enforces the need to continuously monitor these changes in strains prevalence in a particular region. Furthermore, these fluctuations should be considered while administration or development of a vaccine, if rotavirus associated mortality is ever to be controlled.

Epidemiology and genetic diversity of rotavirus strains in children with acute gastroenteritis in Lahore, Pakistan

Pakistan harbors high disease burden of gastro-enteric infections with majority of these caused by rotavirus. Unfortunately, lack of proper surveillance programs and laboratory facilities have resulted in scarcity of available data on rotavirus associated disease burden and epidemiological information in the country. We investigated 1306 stool samples collected over two years (2008–2009) from hospitalized children under 5 years of age for the presence of rotavirus strains and its genotypic diversity in Lahore. The prevalence rate during 2008 and 2009 was found to be 34% (n = 447 out of 1306). No significant difference was found between different age groups positive for rotavirus (p>0.05). A subset of EIA positive samples was further screened for rotavirus RNA through RT-PCR and 44 (49.43%) samples, out of total 89 EIA positive samples, were found positive. G and P type prevalence was found as follows: G1P [4] = 3(6.81%); G1P [6] = 9(20.45%); G1P [8] = 1(2.27%); G2P [4] = 21(47.72%); G2P [8] = 1(2.27%); G9P [4] = 1(2.27%); G9P [6] = 1(2.27%) and G9P [8] = 7(15.90%). Phylogenetic analysis revealed that the VP7 and VP4 sequences clustered closely with the previously detected strains in the country as well as Belgian rotaviruses. Antigenic characterization was performed by analyzing major epitopes in the immunodominant VP7 and VP4 gene segments. Although the neutralization conferring motifs were found variable between the Pakistani strains and the two recommended vaccines strains (Rotarix™ and RotaTeq™), we validate the use of rotavirus vaccine in Pakistan based on the proven and recognized vaccine efficacy across the globe. Our findings constitute the first report on rotavirus’ genotype diversity, their phylogenetic relatedness and epidemiology during the pre-vaccination era in Lahore, Pakistan and support the immediate introduction of rotavirus vaccine in the routine immunization program of the country.

Rotavirus genotypes in children in the community with diarrhea in Madagascar

In the context of the possible introduction of a preventive vaccine against rotaviruses in Madagascar, the G and P genotypes distribution of the rotaviruses circulating in the children in Madagascar was studied, and the presence of emerging genotypes and unusual strains were assessed. From February 2008 to May 2009, 1,679 stools specimens were collected from children ≤5 years old with diarrhea. ELISA was used for antigen detection, and molecular amplification of VP7 and VP4 gene fragments was used for genotyping. Rotavirus antigen was detected in 104 samples (6.2%). Partial sequences of VP7 and VP4 genes were obtained from 81 and 80 antigen-positive stools, respectively. The most frequent G and P types combinations detected were G9P[8] (n = 51; 64.6%), followed by G1P[8] (n = 15; 18.9%), and G1P[6] (n = 8; 10.1%). A few unusual G-P combinations, such as G4P[6] (n = 3; 3.8%), G9P[6] (n = 1; 1.3%), and G3P[9] reassortant feline human virus (n = 1; 1.3%) were identified. Both VP4 and VP7 sequences in one of the three G4P[6] isolates were closely related to those in porcine strains, and one was a reassortant human porcine virus. These findings give an overview of the strains circulating in Madagascar and should help public health authorities to define a vaccine strategy.

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).

Rotavirus infection: a perspective on epidemiology, genomic diversity and vaccine strategies

For centuries, acute diarrhea has been a major cause of death in young children worldwide, and until 1973, before rotavirus was discovered; no infectious agents could be identified in about 80% of patients admitted to hospital with severe dehydrating diarrhea. Rotaviruses have now been shown to cause 40-50% of severe acute diarrhea in young children worldwide in both developing and developed countries. More than 600,000 young children die and approximately 2.4 million hospitalize annually from rotavirus disease, especially in South-East Asia and sub-Saharan Africa. Two safe and effective vaccines are now licensed in 100 countries but used in 17 countries. Rotarix (GSK) vaccine is derived from single attenuated human rotavirus G1P[8], representative of the most common serotype identified worldwide. RotaTeq (Merck) is a pentavalent mixture of naturally attenuated bovine/human rotavirus reassortants representing G1, G2, G3, G4, and P[8] serotypes. Though these vaccines have already dramatically decreased the morbidity associated with rotavirus in countries where they are widely used, the third generation of vaccines, based on inactivated viruses or recombinant virus like particle are already in pipeline. Continuous surveillance and the genetic and antigenic analysis of the various strains of rotavirus circulating worldwide will aid significantly in assessing the effectiveness of these vaccines and monitor emergence of new strains. Introduction of rotavirus vaccines in national vaccine policy along with other childhood vaccines may result in significant reduction in mortality in children in poor socioeconomic countries.

Highly sensitive detection of the group A Rotavirus using Apolipoprotein H-coated ELISA plates compared to quantitative real-time PCR

Background

The principle of a capture ELISA is binding of specific capture antibodies (polyclonal or monoclonal) to the surface of a suitable 96 well plate. These immobilized antibodies are capable of specifically binding a virus present in a clinical sample. Subsequently, the captured virus is detected using a specific detection antibody. The drawback of this method is that a capture ELISA can only function for a single virus captured by the primary antibody. Human Apolipoprotein H (ApoH) or β₂-glycoprotein 1 is able to poly-specifically bind viral pathogens. Replacing specific capture antibodies by ApoH should allow poly-specific capture of different viruses that subsequently could be revealed using specific detection antibodies. Thus, using a single capture ELISA format different viruses could be analysed depending on the detection antibody that is applied. In order to demonstrate that this is a valid approach we show detection of group A rotaviruses from stool samples as a proof of principle for a new method of capture ELISA that should also be applicable to other viruses.

Results

Stool samples of different circulating common human and potentially zoonotic group A rotavirus strains, which were pretested in commercial EIAs and genotyped by PCR, were tested in parallel in an ApoH-ELISA set-up and by quantitative real-time PCR (qPCR). Several control samples were included in the analysis. The ApoH-ELISA was suitable for the capture of rotavirus-particles and the detection down to 1,000 infectious units (TCID_50/ml). Subsets of diagnostic samples of different G- and P-types were tested positive in the ApoH-ELISA in different dilutions. Compared to the qPCR results, the analysis showed high sensitivity, specificity and low cross-reactivity for the ApoH-ELISA, which was confirmed in receiver operating characteristics (ROC) analysis.

Conclusions

In this study the development of a highly sensitive and specific capture ELISA was demonstrated by combining a poly-specific ApoH capture step with specific detection antibodies using group A rotaviruses as an example.

Rotavirus genetic diversity, disease association, and temporal change in hospitalized rural Kenyan children

BACKGROUND

The effectiveness of rotavirus vaccines will be dependent on the immunity conferred against prevalent and emergent variants causing severe diarrheal disease. Longitudinal surveillance of disease-causing strains is a prerequisite to intervention.

METHODS

Molecular characterization was conducted on rotavirus-positive stool samples from children admitted with diarrhea to a rural district hospital during 2002-2004. Extracted viral RNA was separated by polyacrylamide gel electrophoresis, and rotavirus VP4 (P types) and VP7 (G types) specificities were determined.

RESULTS

Among 558 investigated cases, the predominant genotype was P[8]G1 (42%), followed by P[8]G9 (15%), P[4]G8 (7%), P[6]G8 (6%), and P[8]G8 (4%), with 10% mixed strains. Overall, there were 6 different P types and 7 G types. No association was identified between genotype and child age, sex, or severity of diarrhea. The P and G genotypes and polyacrylamide gel electropherotypes showed significant temporal variation in frequency: P[8]G1 decreased from 51% (95% confidence interval [CI], 43%-58%) in 2002 to 30% (95% CI, 24%-37%) in 2004, and P[4]G8 increased from 2% (95% CI, 0%-5%) in 2002 to 13% (95% CI, 9%-19%). Quarterly data revealed seasonally endemic and emergence and/or decay patterns.

CONCLUSIONS

Our study of rotavirus strains causing severe diarrhea in rural Kenyan children showed a predominance of P[8]G1 and confirms the importance of G8 and G9 strains in sub-Saharan Africa. Considerable genetic diversity of rotavirus strains was observed, including substantial mixed and unusual types, coupled with significant temporal strain variation and emergence. These results warn of variable vaccine efficacy and the need for long-term surveillance of circulating rotavirus genotypes.

[Evolution of group A Rotavirus strains circulating in Tunisia over a 3-year period (2005-2007)]

BACKGROUND

Rotaviruses are the most frequent agents associated with diarrhoea in children worldwide. Analysis of mobility of the 11 segments of genomic RNA by polyacrylamide gel electrophoresis (PAGE) yields a pattern which is characteristic for a particular rotavirus isolate. The group A rotaviruses can be further characterized by analysis of VP7 and VP4 genes specificities, responsible for rotavirus classification into G and P genotypes, respectively. The aim of the present study was to determine the evolution of group A Rotavirus strains circulating in Tunisia over a 3-year period (2005-2007).

MATERIAL AND METHODS

A total of 1503 stool samples collected from children less than five years old, consulting or hospitalised in Tunisia for diarrhoea between 2005 and 2007, were screened for the presence of group A Rotaviruses. Rotavirus-positive specimens were further analyzed by PAGE and G/P-genotyped by multiplex semi-nested RT-PCR.

RESULTS

Rotaviruses were detected in 323 stool samples over 1503 (21 %). Long electropherotypes predominated in Tunisia during the whole period of study (N=158 vs N=82 short electropherotypes). VP7 genotyping showed the cocirculation of five different genotypes: G1, G2, G3, G4 and G9. VP4 typing detected four different P-genotypes: P[8], P[4], P[6] and P[11]. Rotavirus strains with G3P[8] specificity were predominating in Tunisia in 2005 and 2006, replaced by G2P[4] strains in 2007.

Secular variation in United States rotavirus disease rates and serotypes: implications for assessing the rotavirus vaccination program

BACKGROUND

Since 2006, we have conducted population-based surveillance for rotavirus disease in children seen in hospitals and emergency departments (EDs) in Monroe County, NY (Rochester), Hamilton County, OH (Cincinnati), and Davidson County, TN (Nashville).

METHODS

During the 2006 and 2007 rotavirus seasons, clinical information and stool specimens were obtained from county children who were <3 years presenting with diarrhea and/or vomiting to the hospital or ED of the only children's hospital in each county. Specimens were tested for rotavirus and genotyped, and rates of hospitalization and ED visits were calculated.

RESULTS

While aggregate rotavirus hospitalization rates for the 3 sites were similar in 2006 and 2007 (22.5/10,000 and 26.8/10,000, respectively), individual rates for the 3 counties differed considerably. The rotavirus hospitalization rate in Rochester between 2006 and 2007 increased 3-fold, but decreased by 33% in Cincinnati and 41% in Nashville over the 2 study years. G1 strains accounted for >80% of strains at all 3 sites in 2006. However, in 2007, the uncommon P[8], G12 strain was detected in 69% of Rochester specimens, while the P[8], G1 strain remained predominant in the other 2 sites. No subjects received rotavirus vaccine in 2006 and coverage with 2 to 3 vaccine doses reached 15% in all 3 communities by June 2007.

CONCLUSIONS

During the 2006 and 2007 rotavirus seasons, with only limited vaccine use, remarkable variability was observed in the population-based rates of severe rotavirus and in the rotavirus serotypes across the 3 sites. This natural secular variability in rotavirus disease must be considered in the assessment of the impact of vaccine on disease rates and rotavirus serotypes.

[Predominance of G9 rotavirus in Valencia and Castellón between 2005 and 2007]

INTRODUCTION

Rotavirus is the leading cause of acute gastroenteritis in young children worldwide. Effective vaccines to prevent rotavirus infections are currently available, although their clinical use is still limited, and rotavirus still causes many episodes of infantile gastroenteritis, mainly during the winter seasons.

OBJECTIVE

To characterise G (VP7) and P (VP4) genotypes of rotaviruses causing acute gastroenteritis in children and to determine the prevalence of genotype G9 rotavirus in three public health areas in the provinces of Valencia and Castellon.

PATIENTS AND METHODS

Five-hundred and forty-one stool samples were prospectively collected from infants and children with gastroenteritis in the period between October 2005 and September 2008. They were analysed for rotavirus by ELISA or by immunochromatography. G and P genotyping was performed by reverse transcription and PCR (RT-PCR).

RESULTS

G and P rotavirus genotypes were characterised in a total of 525 faecal samples (97%), resulting in a global predominance of strains G9P[8] (56.5%) and G1P[8] (29.9%). During the period of time studied, G9P[8] was the G/P combination most frequently detected during the rotavirus seasons 2005-2006 and 2006-2007, being present in 81.2% and 64.7% of the patients, respectively. However, during the 2007-2008 season, G1P[8] strains were the most frequently found (68.8%), with a sharp decrease in G9P[8] strains to 7.2% of the samples.

CONCLUSIONS

Rotavirus G9P[8] have spread rapidly and widely during the 2005-2006 and 2006-2007 seasons, replacing other previously dominant genotypes (G1, G4) in our geographic area. Its incidence has declined sharply in 2007-2008, in which G1P[8] was again the predominating genotype.

Phylogeny of G9 rotavirus genotype: a possible explanation of its origin and evolution

BACKGROUND

G9 rotavirus genotype was isolated in the 1980s and re-emerged without a clear explanation in the mid-1990s as one of the most frequently occurring genotypes with distinct genetic and molecular characteristics.

OBJECTIVES

To study the G9 genotype sequence polymorphisms in Spain and compare them with the human and porcine G9 VP7 genes from the rest of the world. Complete phylogenetic analyses have been done to better characterize G9 genotypes, their relationships and evolution.

STUDY DESIGN

Twelve G9 VP7 genes from Spanish patients were sequenced and compared with 240 G genotype sequences. Nucleotide and amino acid sequence similarity percentages and neighbour-joining dendrograms were used to establish a new phylogenetic analysis.

RESULTS

Eight of the 12 Spanish sequenced samples had different nucleotide translated region sequences, which yielded only five different proteins. New nucleotide and amino acid sequence comparisons were made that differed from previously described results.

CONCLUSIONS

Spanish G9 genotype sequences have similar structure of those belonging to lineage III as the majority of the G9 sequences and share amino acid motifs with other sequences. The phylogenetic analyses of G9 genotypes confirmed the existence of 6 lineages, but did not confirm the 11 sublineages previously reported.

Emerging G9 rotavirus strains in the northwest of China

Although G9 rotaviruses have become one of the important rotavirus genotypes worldwide, they have been uncommon in China. Recently, we reported G9 rotaviruses as a highly prevalent genotype in Xinjiang, the northwest part of China [Yang, X., Matthijnssens, J., Sun, H., Muhamaiti, J., Zhang, B., Nahar, S., Van Ranst, M., Rahman, M., 2008. Temporal changes of rotavirus strain distribution in a northwest city of China, 1996-2005. Int. J. Infect. Dis., June (Epub ahead of print)]. Here we report the genetic variations of the Xinjiang-G9 rotaviruses isolated between 1999 and 2005. Sequence analysis of the VP7 genes of Xinjiang-G9 strains indicated that they were more closely related to the contemporary global G9 strains than to the prototype Chinese G9 strains. However, their VP4 genes were most similar to those from the locally circulating G1P[8], G2P[4], G3P[6] and G3P[8] strains. This indicates that reassortment rather than antigenic drift might be the preferred evolutionary mechanism for the emergence of the G9 rotaviruses in Xinjiang. These findings will be of major significance for understanding the emergence of newly introduced rotavirus strains.

Group A rotavirus strains circulating in the eastern center of Tunisia during a ten-year period (1995-2004)

An epidemiological survey investigating rotavirus infections in children was undertaken in the Eastern Center of Tunisia between January 1995 and December 2004. A total of 982 faecal specimens collected from children less than 5 years in age were screened by enzyme-linked immunosorbent assay (ELISA) or latex agglutination assay for the presence of group A rotavirus antigen. Rotavirus-positive samples were used for G and P typing by multiplex semi-nested reverse transcription-PCR. Rotaviruses were detected in 22% (n = 220) of stools. Of these, 164 were typed for VP7: G genotypes found were G1 (59%), G2 (2%), G3 (9%), G4 (10%), G8 (1%), and G9 (1%). Sixteen specimens (9%) showed mixed G profiles. A total of 119 specimens were typed for VP4. P genotypes detected were P[8] (32%), P[6] (15%), and P[4] (13%). Mixed P profiles were also detected (6%). Although the distribution of the detected genotypes appeared to change annually, G1P[8] rotavirus strains always predominated during the 10-year period of study. This is the first report of rotaviruses in Tunisia with unconventional VP7 serotypes such as G8 and G9, highlighting the need for continual surveillance of emerging strains in Northern Africa. Indeed, the new commercial vaccines only contain the VP7 genes that dictate G1 or G1 to G4 specificities. These vaccines may protect less well against unusual strains circulating in countries planning to implement a rotavirus vaccine strategy.

Diversity of viruses associated with acute gastroenteritis in children hospitalized with diarrhea in Ho Chi Minh City, Vietnam

A molecular epidemiological study on common diarrheal viruses was conducted in Ho Chi Minh City, Vietnam between October 2002 and September 2003. Fecal samples were collected from 1,010 hospitalized children with acute gastroenteritis. Those samples were screened for groups A, B, and C rotavirus, adenovirus, genogroups I and II norovirus (NoV), sapovirus (SaV), and human astrovirus (HAstV) by RT-multiplex PCR, and the positive specimens were characterized further by ELISA, nested PCR, or sequencing. Among the diarrheal viruses detected, group A rotavirus was the most common, with a proportion of 67.4%, whereas NoV GII, adenovirus, SaV, and HAstV were also found in 5.5, 3.2, 0.8, and 0.6%, respectively. It is noteworthy that the group C rotavirus was first reported in Vietnam, with a proportion of 0.5% in this study. Fifty-six of 1,010 (5.5%) samples were found positive with more than one viral agent, in which 25 samples contained both group A rotavirus and NoV GII. Group A rotavirus could be identified throughout year with the peaks in both the dry and rainy season, whereas other viruses prevailed mainly in the rainy season. G-typing for the group A rotavirus showed that genotype 1 was still the most prevailing (33.0%), but interestingly, serotype 9 was emergent and became the third most common rotavirus G-type in these samples (13.7%). The four most common G-P combinations globally, G1P[8], G2P[4], G3P[8], and G4P[8] were found in 46.8% of rotavirus-positive samples, and it is of interest that one unusual rotavirus G9P[19] strain was first detected in Vietnam. The majority of NoV strains belonged to GII/4, and SaV strains mainly clustered with the Manchester strain (GI/1). Twenty-seven out of 32 adenovirus strains were identified as serotype 41. All HAstVs belonged to genotype 1. The results indicated clearly the impact of viral agents causing gastroenteritis and the importance of vaccination against diarrhea in Vietnam.

Group A rotavirus genotypes in Germany during 2005/2006

During the 2005/2006 winter season a total of 802 group A positive rotavirus specimens of patients from different regions throughout Germany were genotyped. Amplicons from a one-tube RT-PCR were typed by analysis of their (type-specific) size using type-specific primers, fluorescent consensus primers and a capillary sequencer for detection. While G1P[8] was predominant (45.8%), G9P[8] has emerged as the second most frequent genotype combination (37.7%). The distribution of genotypes was heterogeneous, regional frequencies regarding G1 and G9 were ranging from 15.0 to 89.3% and from 7.1 to 67.7%, respectively. Furthermore, a few human rotavirus G10P[6] and G10P[8] infections were observed.

Molecular epidemiology of G9 rotaviruses in Taiwan between 2000 and 2002

Since the mid-1990s, novel G9 rotaviruses have been detected in many countries, suggesting that G9 is a globally important serotype. The molecular epidemiology of G9 rotaviruses in Taiwan from 2000 to 2002 was investigated in this study. G9 rotavirus first appeared in 2000 with 4 cases and constituted 33.8% and 54.8% of the rotavirus-positive samples in 2001 and 2002, respectively. These G9 strains belonged to P[8]G9, subgroup II, and long electropherotype, except one belonged to P[4]G9, subgroup II, and short electropherotype. Nucleotide sequencing and phylogenetic analysis of 52 Taiwanese G9 rotaviruses showed that the VP7 genes shared a high degree of identity to overseas G9 rotaviruses detected after 1993 and that the VP8* portions of the VP4 genes were more closely related to those of local rotaviruses of other G types. The two P[8]G9 strains with high nucleotide identities in the VP7 and the partial VP4 genes, 01TW591 of Taiwan from 2001 and 95H115 of Japan from 1995, varied in four genes, genes 2, 3, 7, and 8, which was revealed by RNA-RNA hybridization. Representative strains for different RNA patterns were also analyzed in the partial VP2 and VP3 genes; the nucleotide identities were high between Taiwanese G9 strains and local G3 or G2 strains. These results suggested that Taiwanese G9 rotaviruses possibly had evolved through reassortment between overseas G9 strains and circulating rotaviruses of other G types.

G8 rotavirus strains isolated in the Democratic Republic of Congo belong to the DS-1-like genogroup

Several G8P[6] and G8P[8] rotavirus strains were isolated from hospitalized patients in the Democratic Republic of Congo in 2003. To investigate their overall genomic relatedness and to determine to which genogroup they belonged, the complete genomes of strains DRC88 (G8P[8]) and DRC86 (G8P[6]) were determined. Genomic comparison of these two African G8 strains revealed that 10 out of their 11 gene segments, except for VP4, were nearly identical (>98.9% identical at the nucleotide level), suggesting that this rare G8P[8] rotavirus strain originated recently from a reassortment between a common G8P[6] strain and a strain with a P[8] specificity. A very close evolutionary relationship between 9 out of the 11 gene segments of DRC88 and DRC86 and rotavirus strains belonging to the DS-1-like (G2P[4]) "genogroup" was found, and several possible reassortment events preceding the occurrence of G8P[8] and G8P[6] human rotaviruses were hypothesized. Since the genes of G2P[4] rotavirus strains are very well adapted to infect humans, the acquirement of a new VP7 (G8) gene, and especially the replacement of P[6] (believed to be of animal origin) by P[8] (most common in human rotaviruses), might make DRC88-like rotaviruses very well equipped to become a predominant human rotavirus strain and an important pathogen on the African continent and the rest of the world. These findings have important implications for rotavirus vaccine development and highlight that typing of new rotavirus strains by merely sequencing their VP7 and VP4 genes provides us with only the tip of the iceberg regarding rotavirus diversity.

A Rotavirus Vaccine for Infants: The Asian Experience

Introduction: Severe rotavirus gastroenteritis in children causes significant morbidity world- wide and substantial deaths in developing countries. Hence, a live attenuated vaccine Rotarix™ was developed with human strain RIX4414 of G1P1A P[8] specificity. RIX4414 trials in infants have begun in developed and developing countries worldwide. An overview of RIX4414 in developed and developing countries and prospects with this vaccine in Asia are presented. Methods: Completed RIX4414 trials have been reviewed. Results: Two oral doses of RIX4414 were well tolerated with a reactogenicity profile similar to placebo. RIX4414 was also highly immunogenic, e.g., in a dose-ranging study conducted in Singapore, 98.8% to100% of infants had a vaccine take after 2 doses. RIX4414 did not affect the immune response of simultaneously administered routine infant vaccines. RIX4414 significantly reduced severe rotavirus gastroen- teritis in settings where multiple serotypes including the emerging G9 type co-circulated. Conclusion: These encouraging results warrant further evaluation of the vaccine worldwide and especially in developing countries with the highest need. Therefore, evaluation of the Rotarix™ vaccine is continuing in large phase III trials in Asia and worldwide. Key words: Asia, Attenuated, Developing countries, Gastroenteritis, RIX4414

Rotavirus types in Europe and their significance for vaccination

The degree of diversity of cocirculating human rotavirus wild-type strains is high. This article reviews the occurrence and frequency of rotavirus types in European children younger than 5 years of age during the past 10-15 years. To enable greater understanding of the overall epidemiologic situation, rotavirus types found in animals in Europe are described. In addition, rotavirus types occurring in children outside Europe are considered. Taken together, these data provide an essential background to the development of rotavirus vaccines. The different concepts of immunization with the 2 main rotavirus candidate vaccines are briefly discussed, and their potential impact on the epidemiology of cocirculating rotavirus wild-type viruses is considered. A case is made for comprehensive surveillance of cocirculating human rotavirus types in Europe after the implementation of rotavirus vaccination.

Rotavirus diarrhea in children and adults in a southern city of Brazil in 2003: Distribution of G/P types and finding of a rare G12 strain

Between May and August in 2003, a total of 251 fecal samples were collected from children and adults with diarrhea (5 inpatients and 246 outpatients) at a private hospital in the city of Ponta Grossa, the state of Paraná, Brazil. Group A rotavirus was detected in 71 of 251 (28.3%) specimens: 55 (77.5%) from children under 5 years of age and 16 (22.5%) from individuals aged 6-72 years. All 71 strains exhibited a "long" RNA pattern when analyzed by PAGE. Sixty-one positive samples that yielded enough RNA were submitted to PCR genotyping. The most frequent G/P genotype combination detected was G1P[8] (86.9%; 53/61) followed by G9P[8] (3.3%; 2/61) and G12P[9] (1.6%; 1/61). Rotaviruses with G2, G3, G4, P[4], or P[6] specificity were not detected. For three strains (4.9%) bearing G1 genotype, the VP4 specificity could no be determined, and two specimens (3.3%) remained G/P non-typeable. One rotavirus strain (HC91) bearing G12P[9] genotype with a "long" electropherotype was isolated from an 11-month-old boy with diarrhea for the first time in Brazil. The cell-culture grown HC91 strain was shown to belong to serotype G12 by neutralization.

Serotype diversity and reassortment between human and animal rotavirus strains: implications for rotavirus vaccine programs

The development of rotavirus vaccines that are based on heterotypic or serotype-specific immunity has prompted many countries to establish programs to assess the disease burden associated with rotavirus infection and the distribution of rotavirus strains. Strain surveillance helps to determine whether the most prevalent local strains are likely to be covered by the serotype antigens found in current vaccines. After introduction of a vaccine, this surveillance could detect which strains might not be covered by the vaccine. Almost 2 decades ago, studies demonstrated that 4 globally common rotavirus serotypes (G1-G4) represent >90% of the rotavirus strains in circulation. Subsequently, these 4 serotypes were used in the development of reassortant vaccines predicated on serotype-specific immunity. More recently, the application of reverse-transcription polymerase chain reaction genotyping, nucleotide sequencing, and antigenic characterization methods has confirmed the importance of the 4 globally common types, but a much greater strain diversity has also been identified (we now recognize strains with at least 42 P-G combinations). These studies also identified globally (G9) or regionally (G5, G8, and P2A[6]) common serotype antigens not covered by the reassortant vaccines that have undergone efficacy trials. The enormous diversity and capacity of human rotaviruses for change suggest that rotavirus vaccines must provide good heterotypic protection to be optimally effective.

The emergence of rotavirus genotype G9 in hospitalised children in Slovenia

BACKGROUND

Rotavirus G9 genotype was thought to be the fifth most common genotype circulating amongst the population. In previous studies in Slovenia, only G1, G3 and G4 genotypes were detected.

OBJECTIVES

To determine G and P genotypes of rotaviruses causing dehydrating gastroenteritis in children hospitalised at the University Medical Centre Ljubljana during the winter season 2001-2002. Some data obtained in previous years are included, too.

STUDY DESIGN

For the G and P genotypes determination, we selected 99 of the total of 565 rotavirus positive samples. RT-PCR was carried out for G gene or partial P gene amplification. The RT-PCR product was used as a template for multiplex nested PCR using genotype-specific primers. In untypable samples, a sequence analysis of a short segment of G or P gene was performed. From the period before July 2001, 183 stool samples were examined using the same methods.

RESULTS

Genotype G1 was determined in 37, G4 in 6, and G9 in 28 samples out of 99. Only one sample showed a mixed infection with G1G4 genotype specifics. Following the sequence analysis of the short segment of G gene in 11 G9 genotypes, 2 different clusters of G9 genotype were determined. All samples had the same P genotype--P[8]. G9 genotype had not been detected prior to July 2001.

CONCLUSION

Rotavirus G9 genotype emerged in Slovenia in the year 2001. Two different clusters were determined which have to be further characterised in detail.

Molecular characterizations of human and animal group a rotaviruses in the Netherlands

To gain more insight into interspecies transmission of rotavirus group A, human and animal fecal samples were collected between 1997 and 2001 in The Netherlands. A total of 110 human stool samples were successfully P and G genotyped by reverse transcriptase PCR. All strains belonged to the main human rotavirus genotypes G1 to G4, G9, [P4], [P6], [P8], and [P9]. [P8]G1 was predominant, and 5.5% belonged to the G9 genotype. Eleven percent of all P[8] genotypes could be genotyped only by a recently published modified primer. Rotavirus-positive fecal samples from 28 calf herds were genotyped by DNA sequencing. Genotypes G6 and G10 predominated; G6 and G10 were detected in 22 (78.6%) and 16 (57.1%) of the rotavirus-positive calf herds, respectively. In 12 (42.9%) calf herds, we found mixed infections. Genotype G8 was not found. Genotype G6 bovine rotaviruses were divided into three clusters: UK-like, VMRI-29-like, and Hun4-like. DNA sequencing of a part of the VP7 gene was shown to be useful as a quick determination of uncommon or novel strains of which the genotyping cannot be done by genotyping PCR. Of equine strains, both VP4 and VP7 genes could be used for genotyping: two [P12]G3 and four [P12]G14 equine rotaviruses were determined. We did not find indications for rotavirus interspecies transmissions, although the recently published human G6-Hun4 is genetically related to our G6 bovine isolates. All bovine, porcine, and equine rotaviruses were within genotypes previously reported for these animal species.

Predominance of rotavirus G9 genotype in children hospitalized for rotavirus gastroenteritis in Belgium during 1999–2003

BACKGROUND

Group A rotavirus genotypes G1, G2, G3 and G4 are the main etiological agents of infantile diarrhea. The G9 rotavirus has recently emerged as a fifth important genotype all over the world.

OBJECTIVE

To characterize the VP7 gene of group A rotaviruses from gastroenteritis patients admitted to the Gasthuisberg University Hospital, Leuven, Belgium, during 1999-2003.

STUDY DESIGN

Rotavirus antigen was detected in stool specimens using an enzyme immunoassay. G-typing was performed by reverse transcriptase polymerase chain reaction (RT-PCR) amplification and sequencing of the complete VP7 gene.

RESULTS

The genotype distribution varied markedly over the four rotavirus years in Belgium. In the 1999-2000 rotavirus year, G1 was the predominating type (72%), and G9 was present in 5% of the rotavirus-positive patients. In the 2000-2001 and 2002-2003 years, G9 appeared as the dominating strain (45% and 53%, respectively). In the 2001-2002 year, between two G9 epidemic years, G1 was dominating (66%) but G9 was still present in 24%. All the G9 isolates were combined with P[8] and shared a high gene sequence similarity (<3% sequence divergence on the nucleotide and amino acid level). Phylogenetic analysis of the VP7 genes revealed that our Belgian G9 strains clustered together with recent G9 strains from all over the world, distinct from the prototype G9 strains isolated in the 1980s.

CONCLUSION

Our study indicates that although the first introduction of G9 isolates in the Belgian population was recorded in 1997, G9 strains were able to establish themselves quickly as the predominant genotype. The emergence of G9 as an important pathogen in both developing as industrialized countries necessitates the urgent consideration of the G9 moiety in rotavirus vaccines.

Phylogenetic analyses of human rotavirus in central Taiwan in 1996, 2001 and 2002

BACKGROUND

Rotavirus epidemiology information is required for gastroenteritis disease control and prevention. Information gathered about the serotype distribution of rotaviruses isolated in Taiwan is of crucial significance, before a licensed rotavirus vaccine is introduced.

OBJECTIVES

The purpose of the present study is to investigate the epidemiological diversity of rotaviruses in Taiwan.

STUDY DESIGN

A total of 51 stool samples taken from cases of acute gastroenteritis were collected from three teaching hospitals in central Taiwan in 1996, 2001 and 2002. The samples were subjected to RT-PCR tests of VP7 gene of the human rotavirus group A, B, C.

RESULTS

A total of 16 stool samples were detected positive by RT-PCR and 10 were sequence analyzed and classified into G1, G3, and G9 types. Compared with other HRV strains: the sequences of CS96-40 of G1 are similar to MVD9816 (identity rate 97.15% and 96.09%, respectively, from Uruguay); the sequences of CS02-01 of G3 are similar to 98-B31 (identity rate 98.93% and 98.72%, respectively, from Japan); the sequences of CS01-05, CS01-06, CS01-07, CS01-09, CS01-13, CS02-02, CS02-03, CS02-04 are very similar to other established G9 rotaviruses sequences (identity rate 96.85-99.88%), especially between CS02-04 and SP2737 (from Japan) with an identity rate of 99.88% and 100% nucleotide and amino acid, respectively. Except for CS01-06 strain, it is VR3, but not VR5, VR7 or VR8, that found to be the most frequent mutated amino acid regions of VP7 in these strains.

CONCLUSIONS

Our findings are the first to document the high prevalence of G9 HRV strains in Taiwan, and suggest the re-emergence of G3 strains in central Taiwan since 1991. Epidemiological surveys carried out in this study suggest genotype shifts from type G1 before 1996, to G9 in 2001 and 2002 and the re-emergence of G3 type in 2002.

A porcine G9 rotavirus strain shares neutralization and VP7 phylogenetic sequence lineage 3 characteristics with contemporary human G9 rotavirus strains

Of five globally important VP7 (G) serotypes (G1-4 and 9) of group A rotaviruses (the single most important etiologic agents of infantile diarrhea worldwide), G9 continues to attract considerable attention because of its unique natural history. Serotype G9 rotavirus was isolated from a child with diarrhea first in the United States in 1983 and subsequently in Japan in 1985. Curiously, soon after their detection, G9 rotaviruses were not detected for about a decade in both countries and then reemerged in both countries in the mid-1990s. Unexpectedly, however, such reemerged G9 strains were distinct genetically and molecularly from those isolated in the 1980s. Thus, the origin of the reemerged G9 viruses remains an enigma. Sequence analysis has demonstrated that the G9 rotavirus VP7 gene belongs to one of at least three phylogenetic lineages: lineage 1 (strains isolated in the 1980s in the United States and Japan), lineage 2 (strains first isolated in 1986 and exclusively in India thus far), and lineage 3 (strains that emerged/reemerged in the mid-1990s). Currently, lineage 3 G9 viruses are the most frequently detected G9 strains globally. We characterized a porcine rotavirus (A2 strain) isolated in the United States that was known to belong to the P[7] genotype but had not been serotyped by neutralization. The A2 strain was found to bear serotype G9 and P9 specificities as well as NSP4 [B] and subgroup I characteristics. By VP7-specific neutralization, the porcine G9 strain was more closely related to lineage 3 viruses than to lineage 1 or 2 viruses. Furthermore, by sequence analysis, the A2 VP7 was shown to belong to lineage 3 G9. These findings raise intriguing questions regarding possible explanations for the emergence of variations among the G9 strains.

Rotavirus genotyping: keeping up with an evolving population of human rotaviruses

The use of molecular methods for rotavirus characterisation provides not only increased sensitivity for typing, but also allows accurate and more complete characterisation of strains, and the identification of putative reassortant strains. However, due to the constant accumulation of point mutations through genetic drift, and to the emergence of novel genotypes, possibly zoonotic transmission and subsequent reassortment, the reagents and methods used require close monitoring and updating. Methods and oligonucleotide primers are described to overcome failures to type G9, G10 and P[11] rotavirus strains, and cross-reactivity identified between G10 and G3 rotaviruses.

Emergence of human G9 rotavirus with an exceptionally high frequency in children admitted to hospital with diarrhea in Chiang Mai, Thailand

Among 315 fecal specimens collected from children hospitalized with diarrhea in Chiang Mai, Thailand, in 2000-2001, group A rotavirus was detected in 107 (34.0%). Of these, 98 (91.6%) were G9, 6 (5.6%) were G3 and 3 (2.8%) were G2, respectively. Identification of their P-types demonstrated that 103 (96.3%) were P[8], 3 (2.8%) were P[4], and 1 (0.9%) was P[3] genotypes. Determination of G- and P-type combination revealed that all of G9 isolates were associated with P[8]. G9P[8] was the most predominant genotype and accounted for the majority (91.6%) of rotaviruses detected in this study. Molecular characterization of these G9 isolates demonstrated that all had long electropherotype, 96 of 98 (98.0%) belonged to subgroup II, one belonged to subgroup I and the other one was subgroup unidentifiable. All of G9 isolates possessed NSP4 genetic group B except for one isolate that showed dual genetic group specificities, B and C. The full-length VP7 gene nucleotide sequences among 15 representatives of these G9 strains were found to be highly homologous with percent identities of 99.3%-100%. Comparison with other G9 strains recently isolated showed that their nucleotide sequences were closely related to those of the US strain, US1205 (98.7%-99.0%) and Thai strain, 97CM108 (98.1%-99.0%). Interestingly, they were most closely related to the Japanese strain, 00-SG2509VP7, isolated in the same epidemic season, with percent nucleotide sequence identity of 99.4%-99.8%. The data imply that G9 strains isolated in this study and a G9 strain isolated in Japan in the year 2000 might have descended from the same ancestor.

Evidence of rotavirus AU32 like G9 strains from nontypeable fecal specimens of Indian children hospitalized during 1993-1994

Serotyping of 432 rotavirus positive fecal specimens collected from hospitalized children during 1990-1997 was carried out at National Institute of Virology (NIV), Pune, India, using monoclonal antibodies (MAbs) directed against VP7 determinant of serotypes G1-G4, G6, G8, and G10. However, significant number of specimens, that is, 47.92% remained nontypeable. The aim of the present study was to culture adapt the nontypeable specimens and to characterize them further. Since the fecal specimens were not tested by MAb to G9 serotype, which has emerged as an important serotype infecting humans recently, presence of G9 serotype was expected in nontypeable specimens. Therefore, we selected specimens from those children, who showed higher neutralizing antibody (NAb) titer in their convalescent serum samples to G9 serotype than their mothers. Out of six isolates having long electropherotype, five isolates showed subgroup II, and one showed subgroup I, II. The isolates were confirmed as G9 by MAb based ELISA, neutralization assay, and PCR. The G9 specific nested PCR products of four isolates showed 96-99% identities to AU32 G9 strain reported from Japan. P type of four isolates was determined as P8. Besides isolates, four additional nontypeable fecal specimens were confirmed as G9 by MAb based ELISA. Thus, 10 (28.57%) out of 35 nontypeable specimens were identified as rotavirus serotype G9. The results indicate that serotype G9 may represent significant proportion of specimens, which were previously nontypeable.

Rotavirus serotype G9 strains belonging to VP7 gene phylogenetic sequence lineage 1 may be more suitable for serotype G9 vaccine candidates than those belonging to lineage 2 or 3

A safe and effective group A rotavirus vaccine that could prevent severe diarrhea or ameliorate its symptoms in infants and young children is urgently needed in both developing and developed countries. Rotavirus VP7 serotypes G1, G2, G3, and G4 have been well established to be of epidemiologic importance worldwide. Recently, serotype G9 has emerged as the fifth globally common type of rotavirus of clinical importance. Sequence analysis of the VP7 gene of various G9 isolates has demonstrated the existence of at least three phylogenetic lineages. The goal of our study was to determine the relationship of the phylogenetic lineages to the neutralization specificity of various G9 strains. We generated eight single VP7 gene substitution reassortants, each of which bore a single VP7 gene encoding G9 specificity of one of the eight G9 strains (two lineage 1, one lineage 2 and five lineage 3 strains) and the remaining 10 genes of bovine rotavirus strain UK, and two hyperimmune guinea pig antisera to each reassortant, and we then analyzed VP7 neutralization characteristics of the eight G9 strains as well as an additional G9 strain belonging to lineage 1; the nine strains were isolated in five countries. Antisera to lineage 1 viruses neutralized lineage 2 and 3 strains to at least within eightfold of the homotypic lineage viruses. Antisera to lineage 2 virus neutralized lineage 3 viruses to at least twofold of the homotypic lineage 2 virus; however, neutralization of lineage 1 viruses was fourfold (F45 and AU32) to 16- to 64-fold (WI61) less efficient. Antisera to lineage 3 viruses neutralized the lineage 2 strain 16- to 64-fold less efficiently, the lineage 1 strains F45 and AU32 8- to 128-fold less efficiently, and WI61 (prototype G9 strain) 128- to 1024-fold less efficiently than the homotypic lineage 3 viruses. These findings may have important implications for the development of G9 rotavirus vaccine candidates, as the strain with the broadest reactivity (i.e., a prime strain) would certainly be the ideal strain for inclusion in a vaccine.

Rotavirus typing methods and algorithms

Vaccination is the current strategy for control and prevention of severe rotavirus infections, a major cause of acute, dehydrating diarrhoea in young children worldwide. Public health interventions aimed at improving water, food and sanitation are unlikely adequately to control the disease. The development of vaccines against severe rotavirus diarrhoea is based upon homotypic or heterotypic protection provided against either a single common G serotype (monovalent vaccines) or against multiple serotypes (multivalent vaccines). Rotavirus strain surveillance has a high priority in disease control programmes worldwide. The continued identification of the most common G and P serotypes for inclusion in vaccines is an important priority. And subsequent to the introduction of a vaccine candidate, not only monitoring of circulating strains is recommended, but also surveillance of potential reassortment of animal rotavirus genes from the vaccine into human rotavirus strains is critical. Conventional methods used in the characterisation of rotavirus strains, such as enzyme immunoassay serotyping and reverse‐transcription PCR‐based genotyping often fail to identify uncommon and newly appearing strains. The application of newer molecular approaches, including sequencing and oligonucleotide microarray hybridisation, may be required to characterise such strains. The present paper presents a brief overview of the variety of standard methods available, followed by suggestions for a systematic approach for routine rotavirus strain surveillance as well as for characterisation of incompletely typed rotavirus strains. Improved detection and characterisation of incompletely typed strains will help to develop a comprehensive strain surveillance that may be required for tailoring effective rotavirus vaccines. Published in 2004 by John Wiley & Sons, Ltd.

Characterization of serotype G9 rotavirus strains isolated in the United States and India from 1993 to 2001

The emergence of rotavirus serotype G9 as a possible fifth globally common serotype in the last decade, together with its increasing detection in association with various genome constellations, raises questions about the origins and epidemiological importance of recent G9 isolates. We examined a collection of 40 G9 strains isolated in the United States from 1996 to 2001 and in India since 1993 to determine their VP7 gene sequences, P types, E types, subgroup specificities, and RNA-RNA hybridization profiles. With the exception of two U.S. strains, all of the study strains shared high VP7 gene sequence homology (<2.5% sequence divergence on both the nucleotide and amino acid levels) and were more closely related to other recent isolates than to the first G9 strains isolated in the 1980s. The VP7 gene sequence and RNA-RNA hybridization profiles of the long-E-type strains showed greater variation than the short-E-type strains, suggesting that the latter strains are the result of a relatively recent reassortment event of the G9 VP7 gene into a short-E-type lineage. No evidence for reassortment of genes other than VP4 and VP7 between major human rotavirus genogroups was observed. Except for Om46 and Om67, which formed a distinct clade, phylogenetic analysis showed that most of the study strains grouped together, with some subgroups forming according to genetic constellation, geographic location, and date of isolation. The high potential of G9 strains to generate different P and G serotype combinations through reassortment suggests that it will be important to determine if current vaccines provide heterotypic protection against these strains and underscores the need for continued surveillance for G9 and other unusual or emerging rotavirus strains.

Construction and characterization of rhesus monkey rotavirus (MMU18006)- or bovine rotavirus (UK)-based serotype G5, G8, G9 or G10 single VP7 gene substitution reassortant candidate vaccines

Group A rotaviruses are the single most important etiologic agents of severe diarrhea of infants and young children worldwide and have been estimated to be responsible for approximately 650,000-800,000 deaths annually in children <5-year-old in the developing countries. Thus, the development of a safe and effective rotavirus vaccine has been a global public health goal. Epidemiologic surveillance of rotavirus VP7 (G) serotypes-genotypes conducted in various populations throughout the world has repeatedly shown that approximately 90% of the typeable rotavirus isolates belong to G1-G4. For these reasons, we have developed a rhesus rotavirus (RRV)-based or bovine rotavirus (UK)-based quadrivalent vaccine which is designed to provide antigenic coverage for G1-G4. More recently, G serotypes-genotypes other than G1-G4, including G5, G8-G10, have been detected in various parts of the world. Although the occurrence of such uncommon G types, except for G9, has been focal, still, in order to "be ready and prepared", we have constructed and characterized eight additional reassortant rotavirus vaccines, each of which bears a single human or bovine VP7 gene encoding G serotype 5, 8, 9 or 10 specificity and the remaining 10 genes of RRV strain MMU18006 or bovine rotavirus strain UK. These candidate vaccines could be evaluated singly in special populations or in combination with a RRV- or an UK-based quadrivalent vaccine to broaden its G serotype specificity.