Rotavirus Serotypes Research Articles

Spotlight on Pentavalent Rotavirus Vaccine (RotaTeq®) in the Prevention of Rotavirus Gastroenteritis in Europe†

In Europe, rotavirus gastroenteritis is associated with a significant health, economic, and social burden, as it is responsible for large numbers of hospitalizations and other healthcare encounters among infants and children, as well as numerous days of work lost by parents and caregivers. RotaTeq is a three-dose, orally administered, live, pentavalent human-bovine reassortant rotavirus vaccine used for the active immunization of infants for prevention of rotavirus gastroenteritis. The protective efficacy of RotaTeq has been evaluated in terms of its effects on the incidence of rotavirus gastroenteritis and on healthcare resource use. Clinical trial data from REST (a randomized, double-blind, placebo-controlled, multinational study in ≈70 000 healthy infants aged 6-12 weeks) and various subgroup analyses, including a large European cohort, have shown that RotaTeq may be administered at the same time as various other routine vaccines, has high and sustained efficacy covering the main period of risk for rotavirus gastroenteritis, has early protective efficacy after the first and second doses, reduces rotavirus gastroenteritis-associated hospitalization and emergency department and physician visits, and is generally well tolerated. Moreover, RotaTeq has demonstrated efficacy against the five most prevalent serotypes of rotavirus in Europe (G1-G4, G9), in terms of reductions in associated healthcare resource use. There is also evidence that the widespread use of RotaTeq may provide herd immunity, as it appears to have indirect benefits in older, unvaccinated children. Reports on the 'real world' effectiveness of RotaTeq in Europe are just emerging, but data from the US have shown a rapid and marked reduction in rotavirus burden nationwide during the ≈2-year period following the introduction of RotaTeq and the subsequent availability of official recommendations advocating universal use of the vaccine as part of routine childhood immunization. Postmarketing surveillance data from the US have not identified any concerns, such as an association with intussusception or Kawasaki disease, related to the safety of RotaTeq. In conclusion, RotaTeq is a generally well tolerated vaccine that has efficacy against the five most prevalent serotypes of rotavirus in Europe and provides sustained efficacy over the main risk period for rotavirus gastroenteritis in infants and children, reducing hospitalizations and emergency department visits by decreasing the incidence and severity of illness.

Sustained Efficacy of the Pentavalent Rotavirus Vaccine, RV5, up to 3.1 Years Following the Last Dose of Vaccine

Rotavirus gastroenteritis (RVGE) is a common cause of childhood hospitalizations and emergency department (ED) visits. In the Rotavirus Efficacy and Safety Trial (REST), the pentavalent rotavirus vaccine (RV5) significantly reduced RVGE-associated hospitalizations and ED visits for up to 2 years following the last vaccine dose. This study evaluated whether RV5 remained efficacious beyond 2 years. A total of 20,736 infants from Finland, initially in REST, were followed for RVGE-associated hospitalizations and ED visits in a Finnish extension study (FES) for up to 3.1 years after vaccination (age, ∼3.5 years). The FES added >18,500 person-years and captured 150 RVGE-associated hospitalizations and ED visits (11 RV5; 139 placebo). In REST + FES, RV5 reduced RVGE-associated hospitalizations and ED visits, regardless of rotavirus serotype, by 94.0% (95% confidence interval [CI]: 91.4%-95.9%) for up to 3.1 years after vaccination. RV5 also conferred significant protection against hospitalizations and ED visits associated with rotavirus serotypes G1 (95.5%; 95% CI: 92.8%-97.2%), G2 (81.9%; 95% CI: 16.1%-98.0%), G3 (89.0%; 95% CI: 53.3%-98.7%), G4 (83.4%; 95% CI: 51.2%-95.8%), and G9 (94.2%; 95% CI: 62.2%-99.9%). Rate reductions (95% CI) in hospitalizations and ED visits during the first, second, and third years of life were 94.0% (90.0%-96.5%), 94.7% (90.7%-97.2%), and 85.9% (51.6%-97.2%), respectively. RVGE-associated hospitalizations and ED visits remain common in the second year of life but decrease in the third year of life. RV5 showed sustained protective efficacy against RVGE-associated hospitalizations and ED visits, regardless of rotavirus serotype, for up to 3.1 years after vaccination.

Prevalence and Diversity of Rotavirus Strains in Children with Acute Diarrhea from Rural Communities in the Limpopo Province, South Africa, from 1998 to 2000

Data regarding the prevalence and molecular epidemiology of rotavirus infection in rural areas of Africa are limited. In this study the prevalence and genetic diversity of rotaviruses in a rural South African setting were investigated. During June 1998 to June 2000, 420 stool specimens were collected from children with acute diarrhea who visited primary health care clinics in the rural Vhembe region, Limpopo Province, South Africa. Group A rotaviruses were detected by enzyme-linked immunosorbent assay, and the G and P types were determined by reverse-transcription polymerase chain reaction. Of the 420 specimens, 111 (26.4%) were positive for group A rotavirus; P[6]G1 strains predominated (32.4%), followed by P[8]G1 (13.5%), P[6]G9 (4.5%), P[4]G8 (3.6%), P[4]G1 (3.6%), P[6]G8 (3.6%), and P[6]G2 (2.7%). Dual infections, with >1 P type, were seen in 33 (37.1%) of the positive specimens. The unusual serotype and genotype combinations of rotavirus circulating in the rural communities of the Limpopo Province highlight the need for more studies to monitor the geographic distribution of rotavirus strains in rural African settings.

Characterization of Human Rotavirus Recovered from Children with Acute Diarrhea in Kinshasa, Democratic Republic of Congo

Between July and October of 2003, 2004, and 2005, outbreaks of acute gastroenteritis occurred among children <5 years of age in Kinshasa, Democratic Republic of the Congo. Stool specimens (67 in 2003, 108 in 2004, and 116 in 2005) were collected and screened for rotaviruses using either latex agglutination (Diarlex LAA; Orion Diagnostics) or enzyme immunoassay (IDEIA; DakoCytomation). The molecular characteristics of the rotavirus strains were then determined. Group A rotavirus was detected in 195 (76%) of 258 stool specimens. Polyacrylamide gel electrophoresis was used to observe the 11 rotavirus double-stranded RNA segments in 83% of the 195 rotavirus-positive specimens. Six rotavirus group A electropherotypic patterns were noted, predominantly within the short classic pattern (111 [69%]) and the long pattern (37 [23%]). Mixed patterns were noted in the 14 remaining specimens (9%). Of the 29 samples subjected to subgrouping VP6 enzyme immunoassay, subgroup I predominated. Some of the specimens collected in 2003 (n = 26), 2004 (n = 38), and 2005 (n = 52) were analyzed by reverse-transcription polymerase chain reaction, which showed that t G8P[6] and G8P[8] strains predominated in 2003, and G1P[6] strains with short electropherotypic patterns predominated in 2004 and 2005. The emergence in Kinshasa of G8 serotypes, unusually associated with the P[6] genotype, as well as uncommon G1 rotavirus strains showing a short RNA pattern, is significant in relation to the introduction of a rotavirus vaccine and underscores the need for continued rotavirus serotype surveillance in the Democratic Republic of the Congo.

Influence of Potential Protective Mechanisms on the Development of Live Rotavirus Vaccines

Rotaviruses cause extensive morbidity and mortality worldwide, thus corroborating the need for a vaccine that is effective in all socioeconomic environments. Vaccines evaluated in clinical trials have all been live attenuated rotaviruses that are delivered orally to mimic the excellent protection observed after natural infection. The mechanisms by which these vaccine candidates or wild-type rotaviruses elicit protection are not fully understood. During the 1980s, several candidate vaccines provided little protection, particularly in developing countries, and were discontinued. Two, however, are in the process of being licensed worldwide, and several others are undergoing clinical trials. Development of live rotavirus vaccines has been highly influenced by views regarding the importance of serotype-specific neutralizing antibody. Development of several candidate vaccines is based on the concept that neutralizing antibody is the primary determinant of protection. These candidates, including 1 of the 2 being licensed worldwide (RotaTeq), are composed of multiple rotavirus strains representative of the major human rotavirus serotypes. The other group of candidates has been developed based on the theory that protection is not solely dependent on neutralizing antibody. These candidates are composed of single rotavirus strains and include the other vaccine being licensed worldwide (Rotarix). Studies that provide the basis for each approach will be presented and discussed.

Characterization of 2 Human Genotype G10 Rotavirus Strains, 3008CM and 1784/CI/1999, Isolated in Cameroon and Cote d’Ivoire during the 1999–2000 Rotavirus Season

During routine rotavirus surveillance projects in Cameroon and Cote d'Ivoire, 2 fecal samples collected from 2 children <5 years of age who presented with symptoms of gastroenteritis were found to give anomalous G typing results. These specimens were strongly rotavirus positive by enzyme immunoassay, displayed VP6 subgroup II specificity and long RNA electropherotypes, and were typed as rotavirus serotype G2 with monoclonal antibodies. In addition, the strains were typed as rotavirus VP7 genotype G3 and VP4 genotype P[8] by reverse-transcription polymerase chain reaction. Further investigation of the polymerase chain reaction G-typing results with a second set of primers revealed that the specimens were not genotype G3, and both samples were sequenced to elucidate the problem. Both strains were found to be genotype G10 by nucleotide sequence. Comparison of nucleotide and amino acid sequences and phylogenetic analysis of the African G10 strains revealed that these strains are closely related to the human G10 strains that were detected during the 2001-2003 rotavirus season in Ghana. The detection of G10 rotavirus in Africa adds to the global distribution of this strain and strengthens the need to continue strain surveillance in developing countries to understand the extent of strain distribution and diversity.

Epidemiology of Rotavirus Infection in Children in Blantyre, Malawi, 1997–2007

Acute gastroenteritis caused by rotavirus infection is an important cause of morbidity and mortality among infants and young children in Africa. From 1997 through 2007, we enrolled 3740 children <5 years of age with acute gastroenteritis who received hospital care at the Queen Elizabeth Central Hospital in Blantyre, Malawi. Group A rotavirus was detected in fecal specimens by enzyme immunoassay. Rotavirus strains were characterized for VP7 (G) and VP4 (P) types with use of reverse-transcription polymerase chain reaction. Overall, rotavirus was detected in one-third of children. The median age of children with rotavirus gastroenteritis was 7.8 months, compared with 10.9 months for those without rotavirus in stool specimens (P > .001). Rotavirus circulated throughout the year, with the detection proportion greatest during the dry season (from May through October). A total of 15 single rotavirus strain types were detected during the study period, with genotypes P[8]G1, P[6]G8, P[4]G8, P[6]G1, P[8]G3, and P[6]G9 comprising 83% of all strains characterized. Serotype G12 was detected for the first time in Blantyre during the final 2 years of study. Zoonotic transmission and viral reassortment contributed to the rich diversity of strains identified. Current rotavirus vaccines have the potential to greatly reduce the rotavirus disease burden in Malawi, but they will be required to protect against a broad range of rotavirus serotypes in a young population with year-round rotavirus exposure.

Efficacy of the pentavalent rotavirus vaccine, RotaTeq®, in Finnish infants up to 3 years of age: the Finnish Extension Study

Rotavirus Efficacy and Safety Trial (REST) enrolled nearly 70,000 infants, of whom more than 23,000 were from Finland. REST determined the efficacy of the pentavalent rotavirus vaccine (RV5) against rotavirus-related hospitalisations and emergency department (ED) visits in the first year after vaccination. Finnish infants initially in REST transitioned into the Finnish Extension Study (FES), where they were followed for rotavirus-related hospitalisations and ED visits through their second year of life and beyond. FES identified 150 (31%) additional rotavirus gastroenteritis (RVGE) cases beyond those identified in REST in the Finnish participants. Overall, RV5 reduced RVGE hospitalisations and ED visits, regardless of the rotavirus serotype, by 93.8% (95% confidence interval [CI]: 90.8–95.9%) for up to 3.1 years following the last vaccine dose. Vaccine efficacy against combined hospitalisations and ED visits between ages 4 months to 11 months, 12 months to 23 months, and 24 months to 35 months was 93.9% (95% CI: 89.1–96.9%), 94.4% (95% CI: 90.2–97.0%), and 85.9% (95% CI: 51.6–97.2%), respectively. The reduction of hospitalisations and ED visits due to any acute gastroenteritis, rotavirus or not, was 62.4% (95% CI: 57.6–66.6%) over the entire follow-up period. The results from FES confirm that RV5 induces high and sustained protection against rotavirus-related hospitalisations and ED visits, and has a very substantial impact on all gastroenteritis-related hospitalisations and ED visits into the third year of life in Finnish children.

Pentavalent Rotavirus Vaccine (RotaTeq®)

In Europe, rotavirus gastroenteritis is associated with a significant health, economic and social burden, as it is responsible for large numbers of hospitalizations and other healthcare encounters among infants and children, as well as numerous days of work lost by parents and caregivers. RotaTeq is a three-dose, orally administered, live, pentavalent human-bovine reassortant rotavirus vaccine used for the active immunization of infants for prevention of rotavirus gastroenteritis. The protective efficacy of RotaTeq has been evaluated in terms of its effects on the incidence of rotavirus gastroenteritis and on healthcare resource use. Clinical trial data from REST (a randomized, double-blind, placebo-controlled, multinational study in approximately 70,000 healthy infants aged 6-12 weeks) and various subgroup analyses, including a large European cohort, have shown that RotaTeq may be administered at the same time as various other routine vaccines, has high and sustained efficacy covering the main period of risk for rotavirus gastroenteritis, has early protective efficacy after the first and second doses, reduces rotavirus gastroenteritis-associated hospitalization and emergency department and physician visits, and is generally well tolerated. Moreover, RotaTeq has demonstrated efficacy against the five most prevalent serotypes of rotavirus in Europe (G1-G4, G9), in terms of reductions in associated healthcare resource use. There is also evidence that the widespread use of RotaTeq may provide herd immunity, as it appears to have indirect benefits in older, unvaccinated children. Reports on the 'real world' effectiveness of RotaTeq in Europe are just emerging, but data from the US have shown a rapid and marked reduction in rotavirus burden nationwide during the approximately 2-year period following the introduction of RotaTeq and the subsequent availability of official recommendations advocating universal use of the vaccine as part of routine childhood immunization. Similar benefits have also been demonstrated in Australia after the introduction of a publicly funded rotavirus vaccination programme. Postmarketing surveillance data from the US have not identified any concerns, such as an association with intussusception or Kawasaki disease, related to the safety of RotaTeq. In conclusion, RotaTeq is a generally well tolerated vaccine that has efficacy against the five most prevalent serotypes of rotavirus in Europe and provides sustained efficacy over the main risk period for rotavirus gastroenteritis in infants and children, reducing hospitalizations and emergency department visits by decreasing the incidence and severity of illness.

Biophysical characterization of rotavirus serotypes G1, G3, and G4

The stability of attenuated virus vaccines has traditionally been assessed by a plaque assay to measure the virus’s loss of replication competency in response to a variety of environmental perturbations. Although this method provides information regarding the impact of the vaccine formulation, it involves an empirical approach to evaluate stability. Biophysical studies on the other hand have the potential to provide insight into the mechanisms of inactivation of a viral vaccine in response to a variety of stressed conditions. Herein, we have employed a variety of spectroscopic techniques (i.e., circular dichroism, fluorescence spectroscopy, and dynamic light scattering) for a comprehensive examination of the thermal stability of three live-attenuated human-bovine reassortant rotavirus strains (G1, G3, and G4) in the 5-8 pH range. The spectroscopic methods employed are not specific and response changes reflect an average change over the entire virus structure. The present work, however, suggests the utility of these methods in early formulation of rotaviral vaccines due to their ability to identify regions of marginal stability over which high throughput excipient screening assays can be designed. We have further shown that these methods are sufficiently sensitive to differentiate the stability of the three homologous G-subtypes differing only in the composition of their surface antigenic proteins. The data from these spectroscopic methods are also compared to biological activity using a tissue culture viral infectivity assay. Partial correlation between the structural alterations and losses in activity are observed, further suggesting the utility of biophysical studies in early formulation studies of rotavirus vaccines.

Evaluation of Rapid Antigen Detection Kits for Diagnosis of Equine Rotavirus Infection

We evaluated antigen detection kits for human rotavirus with regard to their usefulness for diagnosing equine rotavirus infection. Limiting dilution analyses showed that of the seven kits investigated the Dipstick `Eiken' Rota (Dipstick) had the highest sensitivity to two serotypes of equine rotavirus. The Dipstick did not cross-react with several equine intestinal pathogens. An investigation using 249 fecal samples indicated that the sensitivity of the Dipstick was 81.9% and 47.3%, and its specificity was 98.2% and 99.0%, and its concordance rate was 92.8% and 68.3%, compared with values obtained using reverse transcription polymerase chain reaction and reverse transcription loop-mediated isothermal amplification, respectively. Although a negative result does not preclude the possibility of equine rotavirus infection, the Dipstick would be useful as routine test for diagnosing equine rotavirus infection in daily clinical practice because of its ease of handling.

Secular Variation in United States Rotavirus Disease Rates and Serotypes

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). 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. 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. 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.

K-I Clinical virology of Rotavirus infection

Rotaviruses are among the major causes of gastroenteritis and diarrhea among children in developed as well as the developing countries. The rapidly evolving strain prevalence and circulation have resulted in the emergence of novel strains over the period worldwide. The introduction of G12 prototype in 1987 from Philippines and subsequently re-emergence among most of the Asian countries along with USA and Europe has provoked new research horizons to address the global distribution of rotavirus serotypes. These newly emerging subtypes and their sustenance among the population have posed tremendous challenge to the development of an effectual vaccine with heterotypic protective efficacy. In Pakistan, no data is available regarding the prevalent rotavirus serotypes; therefore, this is the first study to report the prevalence of G12 strain in Pakistan in hospitalized children with diarrhea addressing a dire need of further large-scale epidemiological surveys to resolve the underlying rotavirus isolates in both the hospitalized and the community neonatal and child population before formulating the vaccine introduction policies in the country's routine immunization program.

Genetic characterization of rotavirus subtypes in Pakistan-first report of G12 genotype from Pakistan under WHO-Eastern Mediterranean region

Rotaviruses are among the major causes of gastroenteritis and diarrhea among children in developed as well as the developing countries. The rapidly evolving strain prevalence and circulation have resulted in the emergence of novel strains over the period worldwide. The introduction of G12 prototype in 1987 from Philippines and subsequently re-emergence among most of the Asian countries along with USA and Europe has provoked new research horizons to address the global distribution of rotavirus serotypes. These newly emerging subtypes and their sustenance among the population have posed tremendous challenge to the development of an effectual vaccine with heterotypic protective efficacy. In Pakistan, no data is available regarding the prevalent rotavirus serotypes; therefore, this is the first study to report the prevalence of G12 strain in Pakistan in hospitalized children with diarrhea addressing a dire need of further large-scale epidemiological surveys to resolve the underlying rotavirus isolates in both the hospitalized and the community neonatal and child population before formulating the vaccine introduction policies in the country's routine immunization program.

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.

Protective Effects of Natural Rotavirus Infection

Rotavirus is a ubiquitous infection that is the leading cause of severe diarrhea worldwide. Severe infections are most commonly observed in the first 2 years of life. Rotavirus-induced diarrhea is associated with substantial morbidity and mortality rates and socioeconomic costs with adverse outcomes particularly prevalent in developing countries. The natural history of rotavirus infection can provide guidance for the development and optimization of an effective vaccine. Epidemiologic studies have demonstrated that children who acquire natural rotavirus infections develop immunity to subsequent infections, with the protective effect increasing with each natural infection. Natural infections also decrease the severity of any subsequent rotavirus infections. Notably, asymptomatic infections provide protection similar to that induced by symptomatic infections. Data also suggest that the antibody response to natural infection is heterotypic, and therefore may provide protection against multiple serotypes. These data suggest that the development of a vaccine that produces asymptomatic infection at an optimal time point may provide effective immunity. An effective vaccine should mimic protection provided by natural infection and provide protection against the most common rotavirus serotypes (ie, G1, G2, G3, G4, G9) and be able to decrease disease severity, reduce hospitalizations, and decrease disease-related costs.

Phylogenetic analysis of novel G12 rotaviruses in the United States: A molecular search for the origin of a new strain

Rotavirus serotype G12 was initially identified in the Philippines in 1987 and was not described again until it reemerged more than 13 years later. G12 strains were first detected in the United States in 2002 and have recently assumed a worldwide distribution. The high similarity between the sequence of the major outer capsid VP7 gene of human G12 strains and the single porcine G12 isolate raised the prospect that human strains may have arisen through reassortment with porcine strains or, alternatively, that the porcine strain originally came from humans. We sequenced portions of the remaining 10 segments of two human G12 strains (G12P[8] and G12P[6]) and a currently circulating common strain (G1P[8]) identified during the 2005-2006 surveillance season and compared the sequences with those of strains available through GenBank. By comparison, the three strains were all Wa-like and not porcine-like. A newly outlined classification system proposed genotypes for each gene segment based on nucleotide similarity. Using this approach, gene segments VP1-3, VP6 and NSP1-5 grouped within the same genotype, indicating that the three strains analyzed were closely related. These results suggest that the novel G12P[8] strain could have been formed by the solitary introduction of a VP7 gene into a globally common rotavirus strain, G1P[8]. Classifying rotavirus strains based only on VP7 (G) and VP4 (P) genotype potentially underestimates diversity and sequence analysis of the other segments is required to assess the complete genetic relationships between strains.

The detection and molecular characterization of human G12 genotypes in South Africa

The last decade has seen an increase in the detection of rotavirus strains other than G1-G4 emerging or even predominating in some settings. The performance of the current rotavirus vaccines against unusual or rare circulating rotavirus serotypes cannot be predicted and continuous monitoring of wild type rotaviruses will remain a priority. Routine molecular rotavirus surveillance conducted in the Gauteng Province, South Africa during 2004, resulted in the detection of strains that could not typed using standard G specific genotyping primers. Sequencing of the first round amplicons revealed 19 serotype G12P[6] strains and one G12P[8] strain. Phylogenetic analyses of the G12 strains indicated that these strains are probably a recent introduction into South Africa and emerged from a strain related to the Indian isolate ISO-5. The association of the South African G12s with the P[6] genotype may suggest a mechanism for unusual strains to become more ecologically suited to local population transmission dynamics. This is the first report of serotype G12 strains on the African continent and continued surveillance will be required to track the emergence of G12 strains in Africa.

VP6 capsid protein of chicken rotavirus strain CH2: Sequence, Phylogeny and In Silico antigenic analyses

The inner capsid protein VP6 of group A rotavirus possesses group and subgroup epitope specificities. Avian rotaviruses have a unique VP6 that is antigenically different from its mammalian counterpart. The lack of information on the VP6 protein of chicken rotavirus strain, CH2, at the genetic and antigenic level was a major motivation for this work. Sequencing of the complete cDNA of the VP6 gene of CH2, revealed a nucleotide (amino acid) identity that varied from 78.3 to 98.5% (86.4–98.2%) when compared with other avian rotaviruses. Regardless of its host origin dissimilarity, CH2 VP6 showed a close sequence homology (97.4–98.2%) with turkey and pigeon rotaviruses. Homology-based modeling of the CH2 VP6 from the corresponding crystal structure of the bovine rotavirus, RF strain, demonstrated that the hypervariable region (residue 228–240) does have a critical role in strain specific antigenic characteristics of avian and mammalian rotaviruses. A predicted conformational epitope encompasses experimentally characterized group and subgroup epitopes suggesting that it is a major antibody binding site on the VP6 protein. The VP6 structure modeling and conformational epitope prediction together with enzyme immuno assay of SG MAbs placed CH2 in SGI/II. The study may be helpful in designing peptides for group A rotavirus diagnostic assays and to achieve heterotypic protection against rotavirus serotypes.

Changing distribution of human rotavirus serotypes during two epidemic outbreaks of gastroenteritis in Campinas, São Paulo, Brazil, 2003–2004: Detection of G6 strains

Background Rotavirus serotypes G1–G4 and G9 are the most important agents of severe diarrhea in children worldwide. Objective To characterize rotavirus serotypes/genotypes causing two large outbreaks of diarrhea in Campinas, São Paulo, during 2003–2004. Study Rotavirus infection was investigated in 328 stool specimens collected from children and adults with diarrhea by PAGE and RT-PCR and further characterized by semi-nested PCR-typing assays. Results G3P[8] (26.1%), G9P[8] (18.7%) and G1P[8] (17.9%) were the most frequently detected serotypes/genotypes. G1P[8] was predominant in 2003, but significantly decreased the following year when G3P[8] and G9P[8] prevailed. G5P[8] was identified in about 9% of the typed specimens from each year consistent with its endemic nature in Brazil for over two decades. The other globally common serotypes (G4P[8] and G2P[4]), uncommon G-P combinations, and multiple G serotypes were also found. Rarely found in humans, and not previously reported in Brazil, serotype G6 was identified in three specimens obtained from children in 2004. Conclusion Multiple rotavirus serotypes were observed co-circulating in the city with serotype predominance changing between the two-year study. This study provides pre-vaccine baseline information on locally endemic strains that might help analysis of post-vaccine data.