Detection and characterization of novel rotavirus strains in the United States

Development of a 1-step TaqMan real-time PCR method for detection of the Bovine Group A Rotavirus

BACKGROUND

The purpose of this study was to develop a 1-step real-time quantitative fluorescence polymerase chain reaction (QF-PCR) method for detecting Bovine Group A Rotavirus (BRVA). The primers and probe were designed targeting the VP6 gene of BRVA. The standard substance was obtained through in vitro transcription. The primers, probe concentration, and annealing temperatures were optimized to determine the optimal system and conditions for the reaction. The specificity, sensitivity, and repeatability of the method were assessed and compared with a reported real-time QF-PCR method for clinical samples.

RESULTS

The results indicated that the detection method can achieve a sensitivity of 3.47 copies/μL and exhibit good specificity by exclusively detecting BRVA without cross-reactivity to other common pathogens in cattle and sheep. The standard curve exhibited a robust linear correlation, and the amplification efficiency was calculated to be 105%. The intra-group and inter-group coefficients of variation were less than 2%. A total of 96 clinical samples were tested and compared with the real-time QF-PCR method that was reported. The coincidence rate was 90.63% (87/96). Furthermore, the clinical samples revealed that the prevalence of BRV in cattle from Fujian Province was 85.42% (82/96).

CONCLUSION

This study has successfully developed a 1-step real-time QF-PCR method for BRVA, which offers an efficient and sensitive technical support for the rapid diagnosis and epidemiological investigation of BRVA.

Rotavirus Strain Trends in United States, 2009–2016: Results from the National Rotavirus Strain Surveillance System (NRSSS)

Before the introduction of vaccines, group A rotaviruses (RVA) were the leading cause of acute gastroenteritis in children worldwide. The National Rotavirus Strain Surveillance System (NRSSS) was established in 1996 by the Centers for Disease Control and Prevention (CDC) to perform passive RVA surveillance in the USA. We report the distribution of RVA genotypes collected through NRSSS during the 2009–2016 RVA seasons and retrospectively examine the genotypes detected through the NRSSS since 1996. During the 2009–2016 RVA seasons, 2134 RVA-positive fecal specimens were sent to the CDC for analysis of the VP7 and VP4 genes by RT-PCR genotyping assays and sequencing. During 2009–2011, RVA genotype G3P[8] dominated, while G12P[8] was the dominant genotype during 2012–2016. Vaccine strains were detected in 1.7% of specimens and uncommon/unusual strains, including equine-like G3P[8] strains, were found in 1.9%. Phylogenetic analyses showed limited VP7 and VP4 sequence variation within the common genotypes with 1–3 alleles/lineages identified per genotype. A review of 20 years of NRSSS surveillance showed two changes in genotype dominance, from G1P[8] to G3P[8] and then G3P[8] to G12P[8]. A better understanding of the long-term effects of vaccine use on epidemiological and evolutionary dynamics of circulating RVA strains requires continued surveillance.

Unexpected Role of Rotavirus G3P[8] Infection in Causing Severe Diarrhea in a Major Tertiary Referral Hospital in the Prevaccine Era

Background: Rotavirus A species is associated with severe gastroenteritis in children. Rotavirus G1P[8] was the most prevalent genotype found in Kuwait in a study conducted between 2005 and 2006. The RotaTeq vaccine was included in the Kuwait national immunization program at the end of 2017. Objectives: Since there is no available data on the rotavirus genotypes circulating before the introduction of the vaccine, we conducted a study to investigate the role of rotaviruses in causing severe diarrhea in children hospitalized in a major tertiary referral hospital in Kuwait during the year 2016. Methods: Viral RNA was isolated from the stool samples of 101 children under five years of age, hospitalized for acute gastroenteritis. Rotavirus VP4 and VP7 dsRNA were detected by RT-PCR, and their partial sequences were analyzed by phylogenic analysis. Results: Rotavirus dsRNA was detected in 24.7% of children with median age of 1 year. The genotype G3P[8] accounted for 47% of cases, followed by G1P[8] (26%), G9P[8] (10.5%), G4P[8] (10.5%), and G9P[4] (5%). Only VP7 nucleotide sequences of rotavirus G3 or G4 type clustered in the same lineage as RotaTeq vaccine, while most VP4 nucleotide sequences of rotavirus P[8] type clustered in a different lineage compared to Rotarix and RotaTeq vaccines. Conclusions: Our findings highlight the role of rotavirus G3P[8] in causing severe diarrhea and invites future investigations to know whether the recent introduction of RotaTeq vaccine in Kuwait selects certain genotypes and subgenomic lineages.

A DS-1 like G9P[6] human strain CDC-6 as a new rotavirus vaccine candidate

Human rotavirus vaccine Rotarix® (G1P[8]) has shown broad cross protection against homotypic and heterotypic Wa-like human rotavirus strains among children worldwide. This vaccine, however, appears to induce slightly less or non-consistent protection against DS-1 like rotavirus P[4] strains in some settings. In addition, children who are secretor or Lewis-negative and are vaccinated with Rotarix® often experience breakthrough infection with P[6] strains. By contrast, P[6] strains infect all children, irrespective of their secretor or Lewis status. In the present study, we report successful adaptation of a DS-1 like human rotavirus G9P[6] strain (CDC-6) to high growth in Vero cells and identify sequence changes that may be critical for enhanced growth in vitro and attenuation in vivo. This human G9P[6] strain could serve as a promising new and potential low-cost vaccine candidate for global use, particularly in targeted population with secretor or Lewis-negative status and high prevalent DS-1 like P[6] strains.

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.

Molecular characterization of emerging G9P[4] rotavirus strains possessing a rare E6 NSP4 or T1 NSP3 genotype on a genogroup-2 backbone using a refined classification framework

Rotavirus infections associated with unusual strains are an emerging concern in rotavirus vaccination programmes. Recently, an increase in circulation of unusual G9P[4] strains was reported from different regions of India, placing this genotype in third position, after G1P[8] and G2P[4], of the most common rotavirus strains. The aim of the present study was to analyse the complete genomic constellation of three G9P[4] strains (RV09, RV10 and RV11), determine their genetic relatedness to other genogroup-2 strains and understand the evolution of a rare E6 and other NSP4 genotypes. All strains revealed the presence of a genogroup-2 backbone, with RV09 constituting the NSP3 T1 genotype and RV10 and RV11 bearing the NSP4 E6 genotype. A refined criterion adopted to classify the nine internal gene segments of G2P[4] and non-G2P[4] strains with the genogroup-2 backbone into lineages and sub-lineages indicated divergence of >8 % (except NSP1: >5.5 %) for lineages and >3 % for sub-lineages. The VP1 and/or VP3 genes of study strains showed close relationships with animal-like human rotaviruses. The estimated evolutionary rate for the NSP4 E6 genotype was marginally higher (3.78×10-3 substitutions per site per year) than that of genotypes E1 (2.6×10-3 substitutions per site per year) and E2 (3.06×10-3 substitutions per site per year), suggesting a step towards adaptation of E6 on a genogroup-2 backbone. The time and origin of the most recent common ancestor of E6 genotype were estimated to be 1981 and South Asia, respectively. Full-genome and evolutionary analyses performed in this study for G9P[4] strains will help better understand the extent of gene reassortment and origin in unusual rotavirus strains that may remain viable and cause infections in humans.

Unexpected spreading of G12P[8] rotavirus strains among young children in a small area of central Italy

Rotavirus gastroenteritis is associated mainly with the five genotypes G1,3,4,9P[8] and G2P[4] that are common worldwide, but emerging strains including G6, G8, and G12 are also reported sporadically. G12P[8] rotavirus was observed unexpectedly to spread in a limited area of Italy during the rotavirus surveillance season 2012-2013. All strains were genotyped for VP7 and VP4 and subjected to phylogenetic analysis. Amino acid sequences of antigenic regions were compared with vaccine and field strains. G12P[8] strains were detected in the stools of 52 of 69 (75%) children infected with rotavirus in the central Italian region of Umbria. All G12 strains belonged to lineage III, and presented the P[8] genotype. Sequence analysis showed close nucleotide identity of both VP4 and VP7 genes among Umbria G12P[8] strains. The VP7 gene was also similar to other G12 strains circulating in different years and countries, and the VP4 gene was closely related to other local and global P[8] strains possessing different G-types. Overall findings suggest either the introduction and evolution of a G12 VP7 gene into the local Wa-like rotavirus population or the spreading of a strain novel for the area. Comparison of the VP8* and VP7 antigenic regions showed high conservation between the amino acid sequences of Umbria G12P[8] strains, and revealed various substitutions in the VP8* antigenic regions between the Italian G12P[8] strains and RotaTeq™ and Rotarix™ vaccine strains. The sudden and unexpected emergence of G12P[8] rotavirus confirms that these strains have the potential to become a sixth common genotype across the world.

Assessment of the risks for human health of adenoviruses, hepatitis A virus, rotaviruses and enteroviruses in the Buffalo River and three source water dams in the Eastern Cape

Buffalo River is an important water resource in the Eastern Cape Province of South Africa. The potential risks of infection constituted by exposure to human enteric viruses in the Buffalo River and three source water dams along its course were assessed using mean values and static quantitative microbial risk assessment (QMRA). The daily risks of infection determined by the exponential model [for human adenovirus (HAdV) and enterovirus (EnV)] and the beta-Poisson model (for hepatitis A virus (HAV) and rotavirus (RoV)) varied with sites and exposure scenario. The estimated daily risks of infection values at the sites where the respective viruses were detected, ranged from 7.31 × 10(-3) to 1 (for HAdV), 4.23 × 10(-2) to 6.54 × 10(-1) (RoV), 2.32 × 10(-4) to 1.73 × 10(-1) (HAV) and 1.32 × 10(-4) to 5.70 × 10(-2) (EnV). The yearly risks of infection in individuals exposed to the river/dam water via drinking, recreational, domestic or irrigational activities were unacceptably high, exceeding the acceptable risk of 0.01% (10(-4) infection/person/year), and the guideline value used as by several nations for drinking water. The risks of illness and death from infection ranged from 6.58 × 10(-5) to 5.0 × 10(-1) and 6.58 × 10(-9) to 5.0 × 10(-5), respectively. The threats here are heightened by the high mortality rates for HAV, and its endemicity in South Africa. Therefore, we conclude that the Buffalo River and its source water dams are a public health hazard. The QMRA presented here is the first of its kinds in the Eastern Cape Province and provides the building block for a quantitatively oriented local guideline for water quality management in the Province.

Distribution of Human Rotaviruses, Especially G9 Strains, in Japan from 1996 to 2000

A 4-year (1996-2000) survey of rotavirus infection involving 2,218 diarrheal fecal specimens of children collected from five regions of Japan was conducted. A total of 642 (28.9%) specimens were found to be rotavirus positive. A changed prevalence pattern of rotavirus G serotype was found with an increase of G9 and G2 and a decrease of G1, although G1 remained the prevailing serotype. Serotype G9 was unexpectedly determined to be the prevailing serotype in Sapporo (62.5%) and Tokyo (52.9%) in 1998-1999, and in Saga (78.4%) in 1999-2000. G9 strains isolated from 1998-1999 belonged to the P[8]-NSP4-Wa-group with long RNA pattern, while, G9 strains isolated from 1999-2000 belonged to three groups, the P[8]-NSP4-Wa-group with long RNA pattern, the P[4]-NSP4-KUN-group with short RNA pattern and a mixed-type group (P[4]/P[8]-NSP4-KUN/Wa-group with long RNA pattern). Both sequence and immunological analysis of VP7 revealed that the G9 strains from 1999-2000 were much more closely related to the G9 strains isolated worldwide in the 1990s, including G9 strains found in Thailand in 1997. However, the G9 strains from 1998-1999 were distinct from these and more closely related to the G9 prototype strains F45, AU32 and WI61 discovered in Japan and the US in the 1980s. Thus the G9 strains isolated in 1998-1999 had progenitors common to the G9 prototype strains, while the strains isolated in 1999-2000 did not directly evolve from them but were related to global G9 strains that have emerged in recent years. These data supported our previous report that G9 rotavirus might exist as two or more subtypes with diverse RNA patterns, P-genotype and NSP4 genogroup combinations (Y.M. Zhou et al., J. Med. Virol. 65: 619-628, 2001) and suggested that G9 rotavirus prevalent in Japan during two successive years belonged to different subtypes. The nucleotide sequences presented in this paper were submitted to DDBJ, EMBL and GenBank nucleotide sequence databases. The accession numbers are: 00-Ad2863VP7 (AB091746), 00-OS2986VP7 (AB091747), 00-SG2509VP7 (AB091748), 00-SG2518VP7 (AB091749), 00-SG2541 (AB091750), 00-SG2864 (AB091751), 00-SP2737VP7 (AB091752), 99-SP1542VP7 (AB091753), 99-SP1904VP7 (AB091754), 99-TK2082VP7 (AB091755) and 99-TK2091VP7 (AB091756).

Comparative evaluation of commercially available manual and automated nucleic acid extraction methods for rotavirus RNA detection in stools

Rotaviruses are a major cause of viral gastroenteritis in children. For accurate and sensitive detection of rotavirus RNA from stool samples by reverse transcription-polymerase chain reaction (RT-PCR), the extraction process must be robust. However, some extraction methods may not remove the strong RT-PCR inhibitors known to be present in stool samples. The objective of this study was to evaluate and compare the performance of six extraction methods used commonly for extraction of rotavirus RNA from stool, which have never been formally evaluated: the MagNA Pure Compact, KingFisher Flex and NucliSENS easyMAG instruments, the NucliSENS miniMAG semi-automated system, and two manual purification kits, the QIAamp Viral RNA kit and a modified RNaid kit. Using each method, total nucleic acid or RNA was extracted from eight rotavirus-positive stool samples with enzyme immunoassay optical density (EIA OD) values ranging from 0.176 to 3.098. Extracts prepared using the MagNA Pure Compact instrument yielded the most consistent results by qRT-PCR and conventional RT-PCR. When extracts prepared from a dilution series were extracted by the 6 methods and tested, rotavirus RNA was detected in all samples by qRT-PCR but by conventional RT-PCR testing, only the MagNA Pure Compact and KingFisher Flex extracts were positive in all cases. RT-PCR inhibitors were detected in extracts produced with the QIAamp Viral RNA Mini kit. The findings of this study should prove useful for selection of extraction methods to be incorporated into future rotavirus detection and genotyping protocols.

Full-genome characterization of a G8P[8] rotavirus that emerged among children with diarrhea in Croatia in 2006

The whole genome of a G8P[8] rotavirus from the 2006 epidemic in Croatia was sequenced and showed a Wa-like genotype constellation. Its VP7 gene clustered with DS-1-like G8 African rotaviruses and a G8P[4] German strain. Remaining genes clustered with contemporary Belgian G1P[8] rotaviruses, suggesting reassortment between human G8 and G1P[8] rotaviruses in Croatia or other European countries.

Quantitative RT-PCR detection of hepatitis A virus, rotaviruses and enteroviruses in the Buffalo River and source water dams in the Eastern Cape Province of South Africa

Human enteric viruses (HEntVs) are a major cause of water-related diseases. The prevalence of hepatitis A virus (HAV), rotaviruses (RoV) and enteroviruses (EnV) in Buffalo River waters was assessed quantitatively over a period of 12 months (August 2010 to July 2011). Seventy-two samples were collected from six sites, including three dams, and concentrated using the adsorption-elution method. Viral RNA was extracted using a commercial kit, and the viruses were quantified by real-time quantitative reverse transcriptase PCR (RT-qPCR). Two or more viruses were detected in 12.5% of the samples. HAV was detected in 43.1% of the samples and in significantly (p < 0.05) varying concentrations of 1.5 × 10(1)–1.9 × 10(5) genome copies/L compared to RoV and EnV, while RoVs were detected in 13.9% of samples, with concentrations ranging from 2.5 × 10(1)–2.1 × 10(3) genome copies/L, and EnV were detected in 9.7% of the samples, with concentrations ranging from 1.3 × 10(1)–8.6 × 10(1) genome copies/L. Only HAV was detected at all the sites, with the Bridle Drift Dam recording significantly higher (p < 0.05) concentrations. The presence of enteric viruses in Buffalo River may constitute public health risks and the incidence of HAV at all the sites could reflect both the epidemiological status of hepatitis A and HAV persistence in the water environments.

Burden of rotavirus hospitalisations in young children in three paediatric hospitals in the United States determined by active surveillance compared to standard indirect methods

AIM

  The number of rotavirus hospitalisations is usually estimated from assigned diagnosis codes for gastroenteritis despite lack of validation for these indirect methods. Reliable estimates before and after introduction of vaccines are needed to quantify the absolute impact of new immunisation programs.

METHODS

  This 2-year study conducted at three hospitals prior to the licensure of the rotavirus vaccines in the USA compared two indirect methods for estimating hospitalisations for rotavirus gastroenteritis with estimates derived from prospective recruitment of children presenting with diarrhoea, vomiting or fever. For active surveillance, rotavirus gastroenteritis was confirmed by demonstration of stool antigen. The indirect residual and proportional methods assumed rotavirus to have caused a proportion of hospitalisations coded as acute gastroenteritis identified from computerised records.

RESULTS

  There were 447 rotavirus hospitalisations among inpatients 31 days through 4 years of age admitted with vomiting and/or diarrhoea, compared with 306 and 228 hospitalisations identified by the two indirect methods. Only 52% of children hospitalised with gastroenteritis received a qualifying diagnosis code at discharge. Relative to active surveillance, the sensitivity and specificity (95% confidence interval (CI)) in identifying rotavirus-attributable hospitalisations was 45% (95% CI: 43-48%) and 89% (88-90%) for the residual method and 34% (30-39%) and 92% (90-94%) for the proportional method.

CONCLUSIONS

  Many children admitted to the hospital with diarrhoea, vomiting or fever were not assigned discharge codes for acute gastroenteritis. Consequently, standard indirect methods missed a substantial number of rotavirus-associated hospitalisations, thereby underestimating the absolute number of children who could potentially benefit from vaccination.

Oral immunoglobulin for the prevention of rotavirus infection in low birth weight infants

BACKGROUND

Rotavirus is a common neonatal nosocomial viral infection and epidemics with the newer P(6)G9 strains have been reported. Local mucosal immunity in the intestine to rotavirus is important in the resolution of infection and protection against subsequent infections. Oral administration of anti-rotaviral immunoglobulin preparations might be a useful strategy in preventing rotaviral infections, especially in low birth weight babies.

OBJECTIVES

To determine the effectiveness and safety of oral immunoglobulin preparations for the prevention of rotavirus infection in hospitalized low birthweight infants (birthweight < 2500 g)

SEARCH METHODS

The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE, EMBASE, CINAHL, biological Abstracts (BIOSIS), Science Citation Index for articles citing Barnes 1982 and the proceedings of the Pediatric Academic Societies from 1991 onwards were searched in July 2011. Ongoing trials were also searched at clinicaltrials.gov and controlled-trials.com

SELECTION CRITERIA

The criteria used to select studies for inclusion were: 1) design: randomized or quasi-randomized controlled trials; 2) participants: hospitalized low birthweight infants; 3) intervention: oral immunoglobulin preparations for prevention of rotavirus infection compared to placebo OR no intervention; 4) at least one of the following outcomes were reported: all cause mortality during hospital stay, mortality due to rotavirus infection during hospital stay, rotavirus infection , duration of diarrhea, need for rehydration, duration of viral excretion, duration of infection control measures, length of hospital stay in days, recurrent diarrhea or chronic diarrhea.

DATA COLLECTION AND ANALYSIS

The two review authors independently abstracted data from the included trials.

MAIN RESULTS

One published study (Barnes 1982) was eligible for inclusion in this review. Barnes 1982 found no significant difference in the rates of rotavirus infection after oral gammaglobulin versus placebo in hospitalized low birthweight babies [RR 1.27 (95% CI 0.65 to 2.37)]. In the subset of infants who became infected with rotavirus after receiving gammaglobulin or placebo for prevention of rotavirus infection, there was no significant difference in the duration of rotavirus excretion between the group who had gammaglobulin (mean 2 days, range 1 to 4 days) and the group who had placebo (mean 3 days, range 1 to 6 days). Barnes 1982 reported no adverse effects after administration of oral immunoglobulin preparations.

AUTHORS' CONCLUSIONS

Current evidence does not support the use of oral immunoglobulin preparations to prevent rotavirus infection in low birthweight infants. Researchers are encouraged to conduct well-designed neonatal trials using the newer preparations of anti-rotaviral immunoglobulins (colostrum, egg yolk immunoglobulins) and include cost effectiveness evaluations.

Oral immunoglobulin for the treatment of rotavirus diarrhea in low birth weight infants

BACKGROUND

Rotavirus infection is the most common neonatal nosocomial viral infection. It is a major health problem worldwide. Epidemics with the newer P(6)G9 strains have been reported in neonatal units globally. These strains can cause severe symptoms in most infected infants. Infection control measures become necessary and the utilization of hospital resources increase. Local mucosal immunity in the intestine to rotavirus is important in the resolution of infection and protection against subsequent infections. Boosting local immunity by oral administration of anti-rotaviral immunoglobulin preparations might be a useful strategy in treating rotaviral infections, especially in low birth weight babies.

OBJECTIVES

To determine the effectiveness and safety of oral immunoglobulin preparations for the treatment of rotavirus diarrhea in hospitalized low birth weight infants (birth weight less than 2500 g)

SEARCH STRATEGY

Electronic databases including The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 3, 2004), MEDLINE, EMBASE and CINAHL, Biological Abstracts (BIOSIS) were searched by the strategy outlined in the protocol. Science Citation Index search for all articles that referenced Barnes 1982 were searched. The proceedings of the Pediatric Academic Societies published online at 'Abstracts Online' were searched. Ongoing registered trials at www.clinicaltrials.gov and www.controlled-trials.com were searched. Authors prominent in the field were contacted for any unpublished articles and more information on published articles was sought. Reference lists of identified clinical trials and personal files were also reviewed. The above search was updated in July 2011.

SELECTION CRITERIA

The criteria used to select studies for inclusion were: 1) DESIGN: randomized or quasi-randomized controlled trials 2) Hospitalized low birth weight infants with rotavirus diarrhea 3) INTERVENTION: Oral immunoglobulin preparations compared to placebo or no intervention 4) At least one of the following outcomes were reported: All cause mortality during hospital stay, mortality due to rotavirus infection during hospital stay, duration of diarrhea, need for rehydration, duration of viral excretion, duration of infection control measures, length of hospital stay in days, recurrent diarrhea or chronic diarrhea

DATA COLLECTION AND ANALYSIS

The two reviewers were to independently abstract data from eligible trials. No data were available for analysis.

MAIN RESULTS

No eligible randomized controlled trials were found.

AUTHORS' CONCLUSIONS

No randomized controlled trials that assessed the effectiveness or safety of oral immunoglobulin preparations for the treatment of rotavirus diarrhea in hospitalized low birth weight infants were found. Clinical trials that address the issue of oral immunoglobulin treatment of rotavirus infection are needed.

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.

Emergence of human rotavirus genotype G9 in metropolitan Detroit between 2007 and 2009

Between January 2007 and April 2009, rotavirus (RV)-positive stool samples from 238 children with acute gastroenteritis, seen at Children's Hospital of Michigan in Detroit, USA, were collected and RV genotyping was performed. G and P genotypes were determined by RT-PCR and nucleotide sequencing was conducted on selected G9 and P[6] strains. Correlation between the severity of gastroenteritis episode and the infecting G genotype was done using a 14-point scoring system. The predominant G genotype was G9 (39.5 %), followed by G1 (35.3 %) and G4 (15.5 %), while P[8] was the most prevalent P genotype (66.5 %), followed by P[4] (21.9 %) and P[6] (11.2 %). The gene combinations G1P[8] and G9P[8] were the most prevalent (21.4 % and 20.6 %, respectively), followed by G4P[8] (13 %) and G9P[6] (8.8 %). Immunization data showed that only 17/238 (7.1 %) children received ≥one dose of RV vaccine (the pentavalent vaccine RotaTeq or the monovalent vaccine Rotarix) and that 10/17 were infected with G4P[8] strains. Severity of RV gastroenteritis episodes was not related to the infecting G genotype. Our results suggest a high proportion of genotype G9 strains in combination with P[8], P[6] and P[4] specificity circulating in the metropolitan Detroit area. While the protective efficacy of the RV vaccines has been demonstrated against G9P[8] strains, the level of cross-protection offered by the vaccines against G9 strains with P[6] and P[4] genotypes in the Detroit paediatric population remains to be determined.

Sequence analysis of the VP7 gene of human rotaviruses G2 and G4 isolated in Japan, China, Thailand, and Vietnam during 2001-2003

Sequence and phylogenetic analyses of the rotavirus VP7 gene were performed on 52 human G2 and G4 strains isolated in Japan, China, Thailand, and Vietnam during 2001-2003. All genotype G2 strains included in the study clustered into lineage II of the phylogenetic tree, together with the majority of global G2 strains detected since 1995. The amino acid substitution at position 96 from aspartic acid to asparagine was noted among the emerging or re-emerging G2 rotavirus strains in Japan, Thailand, and Vietnam during 2002-2003. Genotype G4 strains detected in Vietnam grouped into lineage Ia of the phylogenetic tree, whereas Japanese G4 strains clustered in lineage Ic which included emerging G4 strains from Argentina, Italy, Paraguay, and Uruguay. It is noteworthy that an insertion of asparagine was found at position 76 in all the Japanese strains and that its presence might be involved in the emergence of G4 rotavirus in Japan during 2002-2003.

Rotavirus infections among HIV-infected children in Nairobi, Kenya

Human rotaviruses have emerged as a leading cause of acute diarrhea in children <5 years of age worldwide. Although there are previous reports relating to various aspects of rotaviruses, there is limited data on the involvement of rotavirus infection in HIV-infected children. We therefore evaluated the importance of rotavirus infections in HIV-related diarrhea in Kenyan children. Fecal samples were collected from a total of 207 children during the period February 1999 to June 2000 and screened for HRV antigen by enzyme-linked immunosorbent assay (ELISA). Positive samples were analyzed by VP6 subgroup specificity assay, by polyacrylamide gel electrophoresis (PAGE) and reverse transcriptase/polymerase chain reaction (RT-PCR). Fourteen percent (29/207) of the samples were positive. HIV-seropositive children with diarrhea were more likely than their counterparts without diarrhea to have rotaviruses [23.3% (10/43) versus 2.9% (2/70); p = 0.0001]. Rotavirus strain G3P[6] was predominant. These results indicate that rotavirus is an important viral etiological agent causing diarrhea in HIV-seropositive children.

Licensed Vaccines for Rotavirus Prevention in the US: A Review

Objective:

To review the pharmacology, efficacy, safety, and tolerability of RotaTeq and RotaRix, 2 rotavirus vaccines.

Data Sources:

English-language articles were obtained via MEDLINE (1966-August 2009) and EMBASE (1980-August 2009) searches using the key words rotavirus vaccine, epidemiology, diarrhea, intussusception, RotaShield, RotaTeq, and RotaRix. Bibliographies of selected articles were used to identify additional sources.

Study Selection and Data Extraction:

Available published articles reporting the results of human studies of rotavirus vaccines were reviewed for inclusion in this article. Additional information regarding clinical trials and adverse events was obtained from the manufacturer's prescribing information for each vaccine.

Data Synthesis:

RotaTeq is a live, attenuated human-bovine pentavalent vaccine, and RotaRix is a live, attenuated human vaccine. Both vaccines are approved for the prevention of rotavirus infection and recommended for routine immunization in healthy infants aged 14 weeks to 8 months. The vaccines differ in virologic characteristics, but clinical trials indicate similar efficacy and safety. Each vaccine is more than 70% effective in preventing any severity of rotavirus gastroenteritis and more than 98% effective in preventing severe disease through one full season of rotavirus exposure postvaccination. Efficacy begins to wane during the second season of rotavirus exposure. Post hoc analyses of clinical trials indicated an 85–100% reduction in hospitalizations and emergency department visits following vaccination. Both vaccines have been well tolerated. Fever, vomiting, and diarrhea are the most reported adverse events. Intussusception and Kawasaki syndrome have been reported, but occurrence of these events has not been shown to be significant in comparison with the background rate for each adverse event.

Conclusions:

RotaTeq and RotaRix are effective for the prevention of rotavirus infection in the US, Europe, and Latin America. Additional studies are needed to assess their duration of protection, worldwide efficacy, effect on the reduction of healthcare resource utilization, and adverse event monitoring.

The ever-changing landscape of rotavirus serotypes

Rotavirus is a double-stranded RNA virus that is characterized by substantial genetic diversity. The various serotypes of rotavirus have been determined by the presence of neutralizing epitopes on the outer capsid of the protein shell. At present, 5 rotavirus serotypes (G1, G2, G3, G4, G9) are the predominant circulating strains, accounting for approximately 95% of strains worldwide, although there is considerable geographic variability. Incidence rates for various serotypes also vary temporally with seasonal and year-to-year fluctuations. Unusual serotypes are generally uncommon, but new serotypes can emerge. In particular, G9[P8], a reassortment virus, was first identified in 1983 and in the last 10 to 15 years has become widely distributed worldwide. Indeed, G9[P8] has become highly prevalent in many countries in Europe and Australia, with somewhat lower incidence rates in South America, Africa, and Asia. The heterogeneity and ever-changing epidemiology of rotavirus underscores the need for continued surveillance to ensure that vaccination programs provide optimal protection.

Enhancement of detection and quantification of rotavirus in stool using a modified real-time RT-PCR assay

A sensitive and specific real-time RT-PCR assay to detect rotavirus in stool samples was optimized and validated using a wide range of rotavirus genotypes. The target of the original TaqMan(R) assay is an 87 bp fragment of the highly conserved non-structural protein 3 (NSP3) gene. Here we modified the original assay by introducing degeneracy into the forward primer to account for sequence variation between rotavirus genotypes, added four nucleotides at the 3' end of the reverse primer to reduce its stability, and modified the probe label. Amplification and detection conditions were optimized using purified dsRNA from two cultivated strains. The limit of detection of the modified assay was calculated to be approximately 44 genome copies per reaction. To validate the reactivity of the assay, 103 archived RNAs that had been extracted from stools and genotyped during routine U.S. surveillance were tested. Samples were selected to represent both rare and common genotypes that have been detected in U.S. children. Nine genotypes known to be circulating in the United States were detected by the real-time assay demonstrating broad reactivity. In addition, other enteric viruses were not detected demonstrating that the assay is specific for rotavirus and does not cross-react with other viruses potentially present in stool samples. This real-time assay is an important addition to the arsenal of molecular tools available to quickly identify rotavirus in stool samples during routine surveillance.

Changing profile of rotavirus in Ireland: predominance of P[8] and emergence of P[6] and P[9] in mixed infections

Six hundred and thirty three fecal specimens were collected from patients under 6 years, suffering from non-bacterial, putative viral gastroenteritis in the south of Ireland, between 2003 and 2006. Following laboratory identification of rotavirus as the aetiological agent in 558 specimens, reverse transcriptase polymerase chain reaction was employed to amplify the VP7 and VP4 gene segments of 249 and 245 samples, respectively. G and P typing was subsequently carried out on these amplicons. G1 (65.1%), and G3 (16.1%) were found to be the most prevalent circulating G types over the course of the study. Both G2 (1.2%) and G9 (3.6%), were also found to be circulating, however, these types were less frequently detected. Mixed G type infections were found to account for 41 samples (14%). P typing was carried out on 245 samples. P[8] was the most commonly detected P type over the course of the study (93.5%). Both P[6] and P[9], which had not previously been detected in the Irish population, were detected during this investigation. P[6] was detected in both single and mixed P type infections, while P[9] was detected as part of mixed infections only. The key findings of this study were the emergence of P[6] and P[9] as epidemiologically important rotavirus strains in the Irish population. The profile of rotavirus is changing continuously in Ireland, and continued surveillance of the circulating strains is needed to detect the appearance of new strains, or new variants which could escape immune protection induced by an outdated vaccine.

Modification of rotavirus multiplex RT-PCR for the detection of G12 strains based on characterization of emerging G12 rotavirus strains from South India

Rotaviruses are the major etiological agents of diarrhea in children less than 5 years of age. The commonest G types in humans are G1-4 and G9. G12 is a rare human rotavirus (HRV) strain first reported in the Philippines. In this study, 13 G12 strains obtained from a community-based cohort and a hospital-based surveillance system in 2005 were characterized by phylogenetic analysis of partial nucleotide sequences of VP7, VP6, and NSP4 genes. Sequence and phylogenetic analysis of VP7 gene sequences showed that these southern Indian strains had the greatest homology with G12 strains recently reported from eastern India (97-99% identity both at the nucleotide level and deduced amino acid level) and less homology with the prototype G12 strain, L26 (89-90% identity at the nucleotide level and 90-94% at the deduced amino acid level). Phylogenetic analysis of the VP6 and the NSP4 genes revealed that the Vellore G12 strains belonged to VP6 subgroup II and NSP4 genotype B. The P types associated with these strains were P[6] and P[8]. A G12 type-specific primer was designed for inclusion in an established VP7 G-typing multiplex RT PCR, and tested against a panel of known G types and untyped samples and was found to detect G12 strains in the multiplex-PCR. Close homology of the South Indian G12 strains to those from Kolkata suggests that G12 HRV strains are emerging in India. Methods for characterization of rotaviruses in epidemiological studies need to be updated frequently, particularly in developing countries.

Sequence analysis of the VP7 gene of human rotavirus G1 isolated in Japan, China, Thailand, and Vietnam in the context of changing distribution of rotavirus G-types

Over the last decade, rotavirus G1 has represented the most common genotype worldwide. Since 2000, the prevalence of rotavirus G1 has decreased in some countries such as Japan and China. To monitor the trend of the VP7 encoding gene of rotavirus G1, we performed a sequence analysis of 74 G1 rotavirus strains isolated in Japan, China, Thailand, and Vietnam during the period from 2002 to 2005. The phylogenetic tree showed that all of the studied G1 strains from the four countries clustered into lineage III, the same as the majority of the G1 strains isolated in China and Japan in 1990 and 1991. Examination of the deduced amino acid sequences of the G1 strains from China and Japan revealed an amino acid substitution at position 91 (Asn instead of Thr) in antigenic region A when compared to the G1 strains isolated in China and Japan in 1990, 1991, and global reference strains. For the G1 strains from Thailand and Vietnam, there were three amino acid substitutions, not belonging to any antigenic regions. The study showed that there have been no considerable changes of human rotavirus G1 isolated in Japan, China, Thailand, and Vietnam. Further studies need to be carried out for a better understanding of why such changes in the prevalence of rotavirus G1 occur in these countries.

Symptomatic and subclinical infection with rotavirus P[8]G9, rural Ecuador

Prevalence of this genotype is increasing.

During the past decade, rotavirus genotype G9 has spread throughout the world, adding to and sometimes supplanting the common genotypes G1–G4. We report evidence of this spread in a population sample within rural Ecuador. A total of 1,656 stool samples were collected from both patients with diarrhea and asymptomatic residents in 22 remote communities in northwestern Ecuador from August 2003 through February 2006. Rotavirus was detected in 23.4% of case-patients and 3.2% of controls. From these 136 rotavirus-positive samples, a subset of 47 were genotyped; 72% were of genotype G9, and 62% were genotype P[8]G9. As a comparison, 29 rotavirus-positive stool samples were collected from a hospital in Quito during March 2006 and genotyped; 86% were of genotype P[8]G9. Few countries have reported P[8]G9 rotavirus detection rates as high as those of the current study. This growing prevalence may require changes to current vaccination programs to include coverage for this genotype.

Amino acid substitutions in the VP7 protein of human rotavirus G3 isolated in China, Russia, Thailand, and Vietnam during 2001–2004

The distribution of rotavirus G-types in the world appears to be changing, especially with the emergence of G3 and G9 in many countries. Sequence analysis of the VP7 gene was performed on the 27 human G3 rotavirus strains isolated in China, Russia, Thailand, and Vietnam during 2001-2004. All the strains studied were clustered into the same branch of the phylogenetic tree. The comparison of the G3 deduced amino acid sequences between the studied Chinese strains and the strains circulating in China during 1986-1992 showed a wide range of amino acid substitutions (up to 13 amino acids in the VP7 antigenic regions). The two considerable changes both from aspartic acid to asparagine were located at positions 96 in antigenic region A and 213 in antigenic region C. Those amino acid substitutions of the Chinese G3 strains might involve in the emergence of G3 rotavirus in China during 2001-2003.

Analysis of human rotavirus G1P[8] strains by RFLP reveals higher genetic drift in the VP7 than the VP4 gene during a 4-year period in Mexico

Several studies have demonstrated that rotaviruses of the G1P[8] genotype are among the most important worldwide. Sequence analysis of G1P[8] strains has revealed high genetic variability of VP4 and VP7 genes. The aim of this study was to investigate by restriction fragment length polymorphism (RFLP) analysis the genetic variability of the VP7 and VP4 genes within rotaviruses of the G1P[8] genotype. A total of 60 rotavirus-positive fecal samples genotyped as G1P[8], were collected from children with acute diarrhea under 5 years of age, between October 1995 and October 1998. The VP7 and VP4 genes were amplified by RT/PCR, using the Beg9/End9 primer pair and the Con3 and Con2 primers, respectively. VP7 amplicons were digested with three restriction enzymes Hae III, Taq I and Rsa I in separate reactions and VP4 amplicons were digested similarly with endonucleases Hinf I, Sau96 I and Rsa I. Analysis of the digested VP7 and VP4 amplicons showed a higher genetic drift for the VP7 gene (18 RFLPs) compared to the VP4 gene (9 RFLPs). The combination of profiles for both VP7 and VP4 amplicons, showed 27 different patterns, none of them similar to the Wa-1 strain. Furthermore, RFLP analysis of these G1P[8] strains, clearly differentiated the viruses into two main clusters, both of them sharing the same restriction pattern for the VP4 gene, and a different one for the VP7 gene.

Molecular analysis of VP4, VP7, and NSP4 genes of P[6]G2 rotavirus genotype strains recovered from neonates admitted to hospital in Belém, Brazil

This investigation describes the molecular characterization of P[6]G2 rotavirus strains from hospitalized neonates with community-acquired diarrhea (CAD), nosocomial diarrhea (ND), and asymptomatic nosocomial infection (ANI) in Belém, Brazil. Twenty-six rotavirus strains with P[6]G2 genotype were sequenced to genes coding for VP4, VP7, and NSP4 proteins. Phylogenetic analysis of the VP4 gene, including prototype strains RV3, ST3, M37, and U1205, showed that local P[6]G2 strains clustered forming a distinct lineage (bootstrap of 99%). Brazilian P[6]G2 strains had the highest homology (ranging from 96.0%-98.3%) with the African strain GR1107, G4P[6]. Phylogenetic tree for VP7 gene was constructed including old and new G2 African strains SA3958GR/97, SA356PT/96, SA514GR/87, SA4476PT/97, BF3676/99, GH1803/99, and representative strains of G1, G3, G4, G5, G8, and G9 genotypes. The Brazilian P[6]G2 samples fell into a distinct group (bootstrap value of 97%) and showed homology rates ranging from 92.1% to 93.5% with P[6]G2 African strains BF3676/99, GH1803/99, and SA3958GR/97. Nucleotide sequence analysis of the NSP4 gene, including human prototype strains S2, KUN, DS-1, RV5, RV3 and ST3, and animal prototype OSU, showed that all neonatal isolates fell into genotype A and clustered with a bootstrap value of 100%, with in-group similarities ranging from 99.3% to 100%. In this study no significant differences in nucleotide sequences of the VP4, VP7, and NSP4 genes could be observed when comparing diarrheic (CAD and ND) and non-diarrheic (ANI) babies. Monitoring of rotavirus strains in hospital environments is of particular importance, since it is claimed currently that an efficacious rotavirus vaccine, when available for routine use, will determine an impact on hospital-acquired rotavirus disease.

Association of the G4 rotavirus genotype with gastroenteritis in adults

Rotavirus is the most common etiological cause of acute viral gastroenteritis in infants and young children worldwide, yet its role in the adult population is less well understood. We have recently identified rotavirus as the causative agent of severe diarrhea in adults, specifically in two gastroenteritis outbreaks in separate care for the elderly homes. Strain typing has shown the continued presence of P[8]G1, the emergence of P[8]G9, and the reemergence of P[8]G4. A total of 26 community cases and 6 outbreak cases of rotavirus infection, positive via a molecular screening assay, were subsequently amplified using VP4 and VP7 specific primers (Con2/Con3 and 1A/1B primer sets, respectively). The age range of patients investigated was from <1 year to 89 years. The resulting PCR products were cloned into TOPO10 PCR IV vector and sequenced to give the P- and G-type accordingly. All sequence data were subjected to BLAST analysis. Three different rotavirus types P[8]G1, P[8]G4, and P[8]G9 were identified. Types P[8]G1 and P[8]G9 were identified as circulating within the community, whereas the third type P[8]G4 was identified only in an elderly care outbreak. The identification of G9 rotaviruses supports evidence of emergence of the genotype on a global scale.

Health risks of enteric viral infections in children

Children are at a greater risk of infections from serious enteric viral illness than adults for a number of reasons. Most important is the immune system, which is needed to control the infection processes. This difference can lead to more serious infections than in adults, who have fully developed immune systems. There are a number of significant physiological and behavioral differences between adults and children that place children at a greater risk of exposure and a greater risk of serious infection from enteric viruses. Although most enteric viruses cause mild or asymptomatic infections, they can cause a wide range of serious and life-threatening illnesses in children. The peak incidence of most enteric viral illnesses is in children <2yr of age, although all age groups of children are affected. Most of these infections are more serious and result in higher mortality in children than adults. The fetus is also affected by enterovirus and infectious hepatitis resulting in significant risk of fetal death or serious illness. In addition to the poliovirus vaccine, the only vaccine available is for hepatitis A virus (HAV). A vaccine for rotavirus has currently been withdrawn, pending review because of potential adverse effects in infants. No specific treatment is available for the other enteric viruses. Enteric viral infections are very common in childhood. Most children are infected with rotavirus during the first 2yr of life. The incidence of enteroviruses and the viral enteric viruses ranges from 10% to 40% in children and is largely dependent on age. On average, half or more of the infections are asymptomatic. The incidence of hepatitis A virus is much lower than the enteric diarrheal viruses. There is no current evidence for hepatitis E virus (HEV) acquisition in children in the U.S. Enteric viral diseases have a major impact on direct and indirect health care costs (i.e., lost wages) and amount to several billion dollars a year in the U.S. Total direct and indirect costs for nonhospitalized cases may run from $88/case for Norwalk virus to $1,193/case for enterovirus aseptic meningitis. Direct costs of hospitalization ran from $887/case for Norwalk virus to $86,899/case for hepatitis A. These costs are based on 1997-1999 data. Generally, attack rates during drinking water outbreaks are greater for children than adults. The exception appears to be hepatitis E virus where young adults are more affected. However, pregnant women suffer a high mortality, resulting in concurrent fetal death. Also, secondary attack rates are much higher among children, probably because of fewer sanitary habits among this age group. Overall, waterborne outbreaks of viral disease have a greater impact among children than adults. To better quantify the impact on children, the literature hould be further reviewed for case studies of waterborne outbreaks where data are available on the resulting illness by age group. The EPA and/or Centers for Disease Control should attempt to collect these data as future outbreaks are documented.

Detection of group a human rotavirus G9 genotype circulating in Córdoba, Argentina, as early as 1980

The incidence of human rotavirus G types was determined over a 25-year period (1979-2003) by using reverse transcription-PCR (RT-PCR) to examine 519 stool specimens found to be positive for rotavirus by enzyme linked immunosorbent assay (ELISA) or polyacrylamide gel electrophoresis (PAGE). These stool samples were obtained from children under 3 years old who had been treated for acute diarrhea at public hospitals in Córdoba, Argentina. The present study describes the continued circulation of the common human G types G1 (53.8%), G2 (10.2%), G3 (4.4%), and G4 (27%), and also the detection of the unusual types G8 (0.5%) and G9 (4.2%). Genotype G9 was detected during the 1980-1988 and 1997-2003 periods at relatively low rates. Rotavirus G types distribution was independent of age (1-18 months), gender or out-patient or in-patient status. Unexpectedly, 44.6% of mixed infections were detected, involving common and unusual genotypes. Overall, 95.4% of the typed strains belonged to the most prevalent human serotypes (G1-G4) but the detection of G9 infection throughout this study period highlights the importance of this serotype as a human pathogen.

Development of candidate rotavirus vaccines derived from neonatal strains in India

The need for a rotavirus vaccine in India is based on the enormous burden associated with the >100,000 deaths due to rotavirus diarrhea that occur annually among Indian children. Two rotavirus strains identified during nosocomial outbreaks of rotavirus infection in New Delhi and Bangalore, India, more than a decade ago are being developed as live oral vaccines. Infected newborns had no symptoms, shed virus for up to 2 weeks after infection, mounted a robust immune response, and demonstrated protection against severe rotavirus diarrhea after reinfection. The 2 strains are naturally occurring bovine-human reassortants. The New Delhi strain, 116E, is characterized as having a P[11],G9 genotype, and the Bangalore strain, I321, is characterized as having a P[11],G10 genotype. The strains have been prepared as pilot lots for clinical trials to be conducted in New Delhi. This unique project, which is developing a new rotavirus vaccine in India with the use of Indian strains, an Indian manufacturer, and an Indian clinical development program, aims to expedite introduction of rotavirus vaccines in India.

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.

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.

Detection of unusual strains of RV in patients with acute diarrhoea in Mexico

BACKGROUND

Group A rotaviruses are a major cause of acute gastroenteritis in infants. Human strains with a short RNA pattern generally exhibit subgroup I, G2, P1B[4] specificity, those with a long RNA pattern show subgroup II, G1, G3 or G4, P1A[8] specificity. The presence of strains with unusual specificities has been reported worldwide over the last decade.

OBJECTIVE

To determine antigenic diversity among rotaviruses isolated from patients with diarrhoea.

STUDY DESIGN

A laboratory-based survey study was carried out with faecal samples from patients with acute gastroenteritis form January to April 2000. To classify the samples PAGE and ELISA with specific antibodies to serotype G and P and RT-PCR were carried out.

RESULTS

Twenty one specimens from patients with dehydrating diarrhoea had unusual specifies. Nine specimens had unusual combination of long pattern and subgroup I. Twelve specimens with short pattern belong to G1 serotype. As far as the serotypes and genotypes concern 11 samples were P1A, P[4] and one specimen was P1A, P[9].

CONCLUSIONS

These results demonstrated the unexpected presence of unusual strains of rotavirus in Mexico. Detection of strains with both human and animal characteristics may indicate interspecies transmission of RV between humans and animals.

Global distribution of rotavirus serotypes/genotypes and its implication for the development and implementation of an effective rotavirus vaccine

A safe and effective rotavirus vaccine is urgently needed, particularly in developing countries. Critical to vaccine development and implementation is a knowledge base concerning the epidemiology of rotavirus G and P serotypes/genotypes throughout the world. The temporal and geographical distribution of human rotavirus G and P types was reviewed by analysing a total of 45571 strains collected globally from 124 studies reported from 52 countries on five continents published between 1989 and 2004. Four common G types (G1, G2, G3 and G4) in conjunction with P[8] or P[4] represented over 88% of the strains analysed worldwide. In addition, serotype G9 viruses associated with P[8] or P[6] were shown to have emerged as the fourth globally important G type with the relative frequency of 4.1%. When the global G and/or P type distributions were divided into five continents/subcontinents, several characteristic features emerged. For example, the P[8]G1 represented over 70% of rotavirus infections in North America, Europe and Australia, but only about 30% of the infections in South America and Asia, and 23% in Africa. In addition, in Africa (i) the relative frequency of G8 was as high as that of the globally common G3 or G4, (ii) P[6] represented almost one-third of all P types identified and (iii) 27% of the infections were associated with rotavirus strains bearing unusual combinations such as P[6]G8 or P[4]G8. Furthermore, in South America, uncommon G5 virus appeared to increase its epidemiological importance among children with diarrhea. Such findings have (i) confirmed the importance of continued active rotavirus strain surveillance in a variety of geographical settings and (ii) provided important considerations for the development and implementation of an effective rotavirus vaccine (e.g. a geographical P-G type adjustment in the formulation of next generation multivalent vaccines).

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.

Emergence of G3 and G9 rotavirus and increased incidence of mixed infections in the southern region of Ireland 2001-2004

Two hundred and thirty fecal specimens were collected from children (up to 5 years of age) admitted with suspected rotaviral gastroenteritis at four Irish hospitals (Cork University Hospital, Mercy Hospital, Cork, Waterford Regional Hospital, and Kerry General Hospital) in the southern region of Ireland, between 2001 and 2004. Following laboratory confirmation of the aetiological agent, the rotavirus G-type was determined in all positive samples by reverse transcriptase-polymerase chain reaction (RT-PCR). The distribution of the G-types (n=230) over the 3 year period was G1 (31%), G9 (21.8%), G3 (8.7%), G4 (6.5%), and G2 (3.5%). There were many mixed infections which accounted for 28.5% of the collection. G9 emerged as the most prevalent G type (30.1%) in 2001-2002, whilst G3 first emerged in 2002-2003 and accounted for 15.8% of the collection. Notably, G2 strains were present at a very low frequency (3.5%) during 2001-2004, compared to an earlier study (1997-1999), where they accounted for 28.5% of the specimens. A smaller subset of the study collection was similarly P-typed (n=139). P[8]-type was identified as the most prevalent P-type, accounting for 97.4% (n=186), while P[4] accounted for just 2.6% (n=5) of the collection. The low frequency of P[4] coincided with the decrease in G2 strains in circulation. The key finding in this study was the emergence of G3- and G9-serotypes as epidemiologically important rotavirus strains since 1999, and the low prevalence of the previously common G2 strains in Ireland. The profile of rotavirus is changing continuously in Ireland and the implications for a successful vaccination program are discussed.

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.

Characterization of G10P[11] rotaviruses causing acute gastroenteritis in neonates and infants in Vellore, India

Rotavirus G10P[11] strains, which are commonly found in cattle, have frequently been associated with asymptomatic neonatal infections in India. We report the finding of G10P[11] strains associated with severe disease in neonates in Vellore, southern India. Rotavirus strains from 43 fecal samples collected from neonates with or without gastrointestinal symptoms between 1999 and 2000 were genotyped by reverse transcription-PCR. Forty-one neonates (95%) were infected with G10P[11] rotavirus strains, and 63% of the infections were in children who had gastrointestinal symptoms, including acute watery diarrhea. G10P[11] strains were also seen infecting older children with dehydrating gastroenteritis in Vellore. Characterization of the genes encoding VP7, VP4, VP6, and NSP4 of these strains revealed high sequence homology with the corresponding genes of the asymptomatic neonatal strain I321, which in turn is very closely related to bovine G10P[11] strains circulating in India. No significant differences were seen in the sequences obtained from strains infecting symptomatic neonates or children and asymptomatic neonates.

Diversity of group A human rotavirus types circulating over a 4-year period in Madrid, Spain

The incidence and distribution of human rotavirus G types among children under 5 years old with acute gastroenteritis were determined over a 4-year period (1998 to 2002) by using monoclonal antibodies and reverse transcription-PCR methods. Rotavirus was detected in 1,155 (31%) of 3,760 specimens tested. Rotavirus was studied in every month of the 48-month survey period. Rotavirus activity occurred mainly (51%) in the typically cooler months in Spain (November to February). The age distribution of rotavirus-positive cases showed that 90% of patients (1,038 of 1,155) were under 2 years old. Rotavirus types were determined for 576 of 1,155 patients (50%). G1 was the main genotype detected (53%), and the second most common was G4 (24%). The G2, G9, and G3 rotavirus types were detected in 14, 6, and 2% of the cases, respectively. Dual infections were detected in only 0.6%. The seasonal distribution of genotypes showed a significant genotypic shift: whereas G4 strains predominated (57%) during the 1998 to 2000 seasons, the G1 gradually increased to account for 75% in the 2000 to 2002 seasons. In addition, the present study reports the first detection of the G9 genotype in human fecal samples in Spain. Therefore, additional types may be required for vaccine development strategies that currently target only types G1 to G4.

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.

Assessment of the epidemic potential of a new strain of rotavirus associated with the novel G9 serotype which caused an outbreak in the United States for the first time in the 1995-1996 season

Rotavirus causes severe morbidity in developed countries and frequent deaths (> or = 500,000 per year) in less-developed countries. Historically, four serotypes--G1, G2, G3, and G4-have predominated; they are distinguished by one of two surface neutralization antigens (VP7). However, in 1983 and 1984 we described a new rotavirus serotype, designated G9, in five children hospitalized for diarrhea in Philadelphia, Pa. G9 rotavirus was not identified again in the Western Hemisphere until it caused ca. 50% of the rotavirus disease detected in Philadelphia in the 1995-1996 season. This outbreak allowed us to question whether a rotavirus strain completely new to a well-studied community would target either very young infants or older children, cause especially severe disease, or completely displace previously extant serotypes. We observed a significant excess of G9 infections in younger infants (especially in those < 6 months old) that might be attributed to the lack of G9-specific antibodies in mothers. Of further note, six of the seven oldest patients with rotavirus diarrhea were infected with the G9 strains (not significant). However, the age distribution of children with rotavirus did not differ over a 5-year study period regardless of the infecting serotype. Patients with diarrhea associated with G9 strains did not have disease more severe than that caused by the G1, G2, or G3 serotype. G9 strains did not displace the other serotypes but were virtually completely replaced by G1 or G2 serotypes in the three subsequent rotavirus seasons. We conclude that the abrupt appearance of this novel rotavirus serotype did not present a special threat to public health in the community.