Diversity in Indian equine rotaviruses: identification of genotype G10,P6[1] and G1 strains and a new VP7 genotype (G16) strain in specimens from diarrheic foals in India

Emergence and dissemination of equine-like G3P[8] rotavirus A in Brazil between 2015 and 2021

Rotavirus A (RVA) is a major cause of acute gastroenteritis globally that is classically genotyped by its two immunodominant outer capsid proteins, VP7 (G-) and VP4 (P-). Recent evidence suggests that the reassortant equine-like G3P[8] strain played a substantial role in RVA transmission in Brazil since 2015. To understand its global emergence and dissemination in Brazilian territory, stool samples collected from 11 Brazilian states (n = 919) were genotyped by RT-qPCR and proceeded to sequence the VP7 gene (n = 102, 79 being newly generated) of the G3P[8] samples with pronounced viral loads. Our phylogenetic genotyping showed that G3P[8] became the dominant strain in Brazil between 2017 and 2020, with equine-like variants representing 75%-100% of VP7 samples in this period. A Bayesian discrete phylogeographic analysis strongly suggests that the equine-like G3P[8] strain originated in Asia during the early 2010s and subsequently spread to Europe, the Caribbean, and South America. Multiple introductions were detected in Brazil between 2014 and 2017, resulting in five national clusters. The reconstruction of the effective population size of the largest Brazilian cluster showed an expansion until 2017, followed by a plateau phase until 2019 and subsequent contraction. Our study also supports that most mutations fixed during equine-like G3P[8] evolution were synonymous, suggesting that adaptive evolution was not an important driving force during viral dissemination in humans, potentially increasing its susceptibility to acquired immunity. This research emphasizes the need for comprehensive rotavirus genomic surveillance that allows close monitoring of its ever-shifting composition and informs more effective public health policies.IMPORTANCEOur original article demonstrated the origin and spread in a short time of equine-like G3P[8] in Brazil and the world. Due to its segmented genome, it allows numerous mechanisms including genetic drift and reassortment contribute substantially to the genetic diversity of rotavirus. Although the effectiveness and increasing implementation of vaccination have not been questioned, a matter of concern is its impact on the emergence of escape mutants or even the spread of unusual strains of zoonotic transmission that could drive epidemic patterns worldwide. This research emphasizes the need for comprehensive rotavirus genomic surveillance, which could facilitate the formulation of public policies aimed at preventing and mitigating its transmission.

High prevalence of equine-like G3P[8] rotavirus in children and adults with acute gastroenteritis in Thailand

Group A rotavirus (RVA) is a major cause of acute gastroenteritis in infants and young children worldwide. This study aims to clarify the distribution of G/P types and genetic characteristics of RVAs circulating in Thailand. Between January 2014 and September 2016, 1867 stool specimens were collected from children and adults with acute gastroenteritis in six provinces in Thailand. RVAs were detected in 514/1867 (27.5%) stool specimens. G1P[8] (44.7%) was the most predominant genotype, followed by G3P[8] (33.7%), G2P[4] (11.5%), G8P[8] (7.0%), and G9P[8] (1.3%). Unusual G3P[9] (0.8%), G3P[10] (0.4%), G4P[6] (0.4%), and G10P[14] (0.2%) were also detected at low frequencies. The predominant genotype, G1P[8] (64.4%), in 2014 decreased to 6.1% in 2016. In contrast, the frequency of G3P[8] markedly increased from 5.5% in 2014 to 65.3% in 2015 and 89.8% in 2016. On polyacrylamide gel electrophoresis, most (135/140; 96.4%) of the G3P[8] strains exhibited a short RNA profile. Successful determination of the nucleotide sequences of the VP7 genes of 98 G3P[8] strains with a short RNA profile showed that they are all equine-like G3P[8] strains. On phylogenetic analysis of genome segments of two representative Thai equine-like G3P[8] strains, it was noteworthy that they possessed distinct NSP4 genes, one bovine-like and the other human-like. Thus, we found that characteristic equine-like G3P[8] strains with a short RNA electropherotype are becoming highly prevalent in children and adults in Thailand.

Emergence and spread of G3P[8] rotaviruses possessing an equine-like VP7 and a DS-1-like genetic backbone in the Basque Country (North of Spain), 2015

In March 2015, an atypical G3P[8] rotavirus with an equine-like VP7 gene was detected in Gipuzkoa (Basque Country, Spain) and spread contributing significantly to the seasonal epidemic. The strain was identified in fecal samples collected from 68 patients, mainly children from rural and urban settings with acute gastroenteritis, representing 14.9% of the 455 rotavirus strains genotyped between July 2014 and June 2015. Seven patients (10.3%) were hospitalized. Full genome analysis of six of these strains revealed a DS-1-like genotype constellation, G3-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2, and showed that most genome segments shared the highest nucleotide sequence identity with strains isolated in Japan, Thailand, Australia and the Philippines. The strains of Gipuzkoa were similar to novel G3P[8] reassortant rotaviruses with an equine-like VP7 gene and a DS-1-like genetic backbone that emerged in the Asia-Pacific Region in 2013. The study highlights the circulation of these atypical rotaviruses outside the Asia-Pacific Region of origin, and their emergence in a European Region. Due to their unusual genotype constellation, these strains pose a challenge for the rotavirus strain surveillance, since G-/P-typing, the most commonly used classification system, cannot identify this type of intergenogroup reassortants.

Reassortment of Human and Animal Rotavirus Gene Segments in Emerging DS-1-Like G1P[8] Rotavirus Strains

The emergence and rapid spread of novel DS-1-like G1P[8] human rotaviruses in Japan were recently reported. More recently, such intergenogroup reassortant strains were identified in Thailand, implying the ongoing spread of unusual rotavirus strains in Asia. During rotavirus surveillance in Thailand, three DS-1-like intergenogroup reassortant strains having G3P[8] (RVA/Human-wt/THA/SKT-281/2013/G3P[8] and RVA/Human-wt/THA/SKT-289/2013/G3P[8]) and G2P[8] (RVA/Human-wt/THA/LS-04/2013/G2P[8]) genotypes were identified in fecal samples from hospitalized children with acute gastroenteritis. In this study, we sequenced and characterized the complete genomes of strains SKT-281, SKT-289, and LS-04. On whole genomic analysis, all three strains exhibited unique genotype constellations including both genogroup 1 and 2 genes: G3-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2 for strains SKT-281 and SKT-289, and G2-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2 for strain LS-04. Except for the G genotype, the unique genotype constellation of the three strains (P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2) is commonly shared with DS-1-like G1P[8] strains. On phylogenetic analysis, nine of the 11 genes of strains SKT-281 and SKT-289 (VP4, VP6, VP1-3, NSP1-3, and NSP5) appeared to have originated from DS-1-like G1P[8] strains, while the remaining VP7 and NSP4 genes appeared to be of equine and bovine origin, respectively. Thus, strains SKT-281 and SKT-289 appeared to be reassortant strains as to DS-1-like G1P[8], animal-derived human, and/or animal rotaviruses. On the other hand, seven of the 11 genes of strain LS-04 (VP7, VP6, VP1, VP3, and NSP3-5) appeared to have originated from locally circulating DS-1-like G2P[4] human rotaviruses, while three genes (VP4, VP2, and NSP1) were assumed to be derived from DS-1-like G1P[8] strains. Notably, the remaining NSP2 gene of strain LS-04 appeared to be of bovine origin. Thus, strain LS-04 was assumed to be a multiple reassortment strain as to DS-1-like G1P[8], locally circulating DS-1-like G2P[4], bovine-like human, and/or bovine rotaviruses. Overall, the great genomic diversity among the DS-1-like G1P[8] strains seemed to have been generated through reassortment involving human and animal strains. To our knowledge, this is the first report on whole genome-based characterization of DS-1-like intergenogroup reassortant strains having G3P[8] and G2P[8] genotypes that have emerged in Thailand. Our observations will provide important insights into the evolutionary dynamics of emerging DS-1-like G1P[8] strains and related reassortant ones.

Quantification of human infection risk caused by rotavirus in surface waters from Córdoba, Argentina

Fecal contamination of water is a worrying problem because it is associated with the transmission of enteric pathogenic microorganisms that can cause many infectious diseases. In this study, an environmental survey was conducted to assess the level of viral contamination by viable enterovirus and rotavirus genome in two recreational rivers (Suquía and Xanaes) of Córdoba, Argentina. Quantitative microbial risk assessment (QMRA) was calculated to estimate the risk of rotavirus infection. Water sampling was carried out during a one-year period, the presence of total and fecal coliforms was determined and water samples were then concentrated for viral determination. Cell culture and indirect immunofluorescence were applied for enterovirus detection and RT-qPCR for rotavirus quantification. Coliform bacteria levels found in Suquía River often far exceeded the guideline limits for recreational waters. The Xanaes exhibited a lower level of bacterial contamination, frequently within the guideline limits. Enterovirus and rotavirus were frequently detected in the monitoring rivers (percentage of positive samples in Suquía: 78.6% enterovirus, 100% rotavirus; in Xanaes: 87.5% enterovirus, 18.7% rotavirus). Rotavirus was detected at a media concentration of 5.7×10(5) genome copies/L (gc/L) in the Suquía and 8.5×10(0)gc/L in the Xanaes. QMRA revealed high risk of rotavirus infection in the Suquía, at sampling points with acceptable and non-acceptable bacteria numbers. The Xanaes showed significantly lower health risk of rotavirus infection but it proved to be a public health hazard. The viral occurrence was not readily explained by the levels of bacteria indicators, thus viral monitoring should be included to determine microbiological water quality. These findings provide the first data of QMRA for recreational waters in Argentina and reveal the need for public awareness of the health implications of the use of the river waters.

Molecular epidemiology of rotavirus in children and animals and characterization of an unusual G10P[15] strain associated with bovine diarrhea in south India

Rotaviruses are enteric pathogens causing acute, watery, dehydrating diarrhea in various host species, including birds and mammals. This study collected data on the disease burden and strain prevalence of Group A rotavirus in animals and humans in Vellore and investigated interspecies transmission by comparison of circulating genotypes. Stool samples from children aged less than 5 years, admitted to the hospital between January 2003 and May 2006 for diarrhea and diarrheal samples from animals that were collected from a veterinary clinic and several dairy farms near Vellore between February 2007 and May 2008 were processed and subjected to RNA extraction and reverse-transcription PCR for genotyping of VP7 and VP4. Of 394 children with diarrhea, 158 (40%) were positive for rotavirus and the common G types identified were G1 (47, 29.7%), G2 (43, 27.2%), G9 (22, 13.9%), G10 (2, 1.2%), G12 (1, 0.6%) and mixed infections (27, 17.8%). The common P types were P[4] accounting for 57 (36%) samples, P[8] 57 (36%), P[11] 3 (1.8%) and P[6] 2 (1.2%). Of 627 animals, 35 (1 bullock, 2 goats, 32 cows) were found to be infected with rotavirus (5.5%). The common G types identified in order of frequency were G6 (17, 48.5%), G2 (10, 28%), G10 (4, 11%), G8 (2, 5.7%) and mixed infections (2, 5.7%). The common P types were P[6] accounting for 16 (46%) samples, P[4] 7 (20%), P[1] 3 (8.5%) and P[8] 3 (8.5%). An unusual P type P[15] was seen in one sample in combination with G10. The finding of G2 infections which are rarely identified in animals implies anthroponotic transmission since this genotype is predominantly associated with infection in humans.

Exotic rotaviruses in animals and rotaviruses in exotic animals

Group A rotaviruses (RVA) are a major cause of viral diarrhea in the young of mammals and birds. RVA strains with certain genotype constellations or VP7-VP4 (G-P) genotype combinations are commonly found in a particular host species, whilst unusual or exotic RVAs have also been reported. In most cases, these exotic rotaviruses are derived from RVA strains common to other host species, possibly through interspecies transmission coupled with reassortment events, whilst a few other strains exhibit novel genotypes/genetic constellations rarely found in other RVAs. The epidemiology and evolutionary patterns of exotic rotaviruses in humans have been thoroughly reviewed previously. On the other hand, there is no comprehensive review article devoted to exotic rotaviruses in domestic animals and birds so far. The present review focuses on the exotic/unusual rotaviruses detected in livestock (cattle and pigs), horses and companion animals (cats and dogs). Avian rotaviruses (group D, group F and group G strains), including RVAs, which are genetically divergent from mammalian RVAs, are also discussed. Although scattered and limited studies have reported rotaviruses in several exotic animals and birds, including wildlife, these data remain to be reviewed. Therefore, a section entitled "rotaviruses in exotic animals" was included in the present review.

An overview of calf diarrhea - infectious etiology, diagnosis, and intervention

Calf diarrhea is a commonly reported disease in young animals, and still a major cause of productivity and economic loss to cattle producers worldwide. In the report of the 2007 National Animal Health Monitoring System for U.S. dairy, half of the deaths among unweaned calves was attributed to diarrhea. Multiple pathogens are known or postulated to cause or contribute to calf diarrhea development. Other factors including both the environment and management practices influence disease severity or outcomes. The multifactorial nature of calf diarrhea makes this disease hard to control effectively in modern cow-calf operations. The purpose of this review is to provide a better understanding of a) the ecology and pathogenesis of well-known and potential bovine enteric pathogens implicated in calf diarrhea, b) describe diagnostic tests used to detect various enteric pathogens along with their pros and cons, and c) propose improved intervention strategies for treating calf diarrhea.

Epidemiology and clinical features of rotavirus and norovirus infection among children in Ji'nan, China

Background

Acute gastroenteritis caused by bacteria, virus and parasite is an important cause of childhood morbidity and mortality in developing countries. Rotavirus and norovirus have been recognized as the most common pathogens causing acute gastroenteritis among children. However, there is still no valuable data about infections of rotavirus and norovirus in children in Ji’nan, an eastern city in China. The aims of the present study are to determine the incidence of rotavirus and norovirus associated acute gastroenteritis in Ji’nan among children, to characterize rotavirus and norovirus strains circulating during this period; and to provide useful epidemiological and clinical data.

Methods

Fecal specimens and clinical data were collected from 767 children (502 outpatients and 265 inpatients) under 5 years of age with acute diarrhea at Shandong University Qilu Hospital and Qilu children’s Hospital in Ji’nan, China between February 2011 and January 2012. Virus RNA was extracted, amplified, electrophoresed, sequenced and phylogenetically analyzed to determine the prevalent genotypes. Chi-square and U test were used to compare characteristics of clinical manifestation in each group.

Results

Of the 767 specimens 263 (34.3%) were positive for rotavirus and 80 (10.4%) were positive for norovirus. Among 263 rotavirus positive cases, G3 (40.7%) was the most prevalent serotype, P[8] (46.8%) was the dominant genotype and G3P[8] (31.9%) was the most common combination. All of the norovirus strains belonged to GII genogroup including GII.3, GII.4 and GII.6, of which GII.4 (61.2%) was the predominant genotype. Phylogenetic analysis of the GII.4 sequences showed that 18 GII.4 strains belonged to GII.4 2004–2006 cluster and 31 GII.4 strains were divided into GII.4 2006b cluster. A peak number of rotavirus infections was observed during the cold season from November to next January. Higher rates of norovirus infections were detected from September to November. Most patients with rotavirus and norovirus associated diarrhea experienced vomiting (88.2% and 67.5%, respectively) and fever (79.1% and 46.3%, respectively).

Conclusions

The present study showed that rotavirus and norovirus were still the important causative agents of pediatric diarrhea in Ji’nan during this period.

Genome sequence of an unusual human G10P[8] rotavirus detected in Vietnam

A rare human G10P[8] rotavirus with a reassortment between bovine and human viruses was detected from a patient with acute gastroenteritis in Vietnam. Genetic analysis using complete coding sequences of all segments showed a genomic constellation of this virus of G10-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1. Its VP7 region was genetically related to that of a bovine rotavirus derived from Australia (strain VICG10.01), whereas all other genes were identical to those of a human rotavirus derived from Australia (strain Victoria/CK00047). These results indicate a possibility that the reassortment of the rotavirus was caused by immune escape in Australia and the rotavirus was carried to Vietnam. Additionally, this finding will help further understanding the evolution of rotaviruses circulating in Vietnam.

A large outbreak of enteritis in goat flocks in Marmara, Turkey, by G8P[1] group A rotaviruses

Group A rotaviruses are regarded as major enteric pathogens of large ruminants, while their impact on the health of small ruminants is not well documented. We report the detection of group A rotavirus from a large outbreak of enteritis that occurred in two goat flocks in the town of Kırklareli, Marmara Region, Turkey, in 2007. The disease was observed in young kids, with high morbidity and mortality rates, but not in adult animals. Rotavirus antigen was detected in the stools of the examined animals, and rotaviruses were isolated in MA104 cells. Upon sequencing of the VP4, VP6, VP7 and NSP4 genes, the strain (RVA/goat-tc/TUR/Kirklareli/2007/G8P[1]) was characterized as G8P[1], with E2 NSP4 and VP6 I2 genotype. These findings indicate that group A rotavirus should be included in the diagnostic algorithms for enteric disease in small ruminants.

Rotavirus diarrhea in bovines and other domestic animals

Rotavirus diarrhea is the major cause of death of millions of children in developing countries besides causing economically significant malady in neonates of many domestic animals. In neonates, the infection is non-viremic, have very short incubation period, and manifests profuse diarrhea and severe dehydration. Concurrent infection with secondary pathogens may augment the disease severity. Diarrhea occurs due to virus-mediated destruction of absorption efficient enterocytes, activation of enteric nervous system, or due to a rotavirus enterotoxin. Diagnosis of the infection relies on conventional techniques like isolation in MA 104 cell lines, electron microscopy, electro-pherotyping, and various serological tests. Presently, diagnosis and molecular typing is performed using serotype specific RT-PCR, sequencing or genomic hybridization techniques. As the rotaviruses are known to exhibit extreme genetic diversity and outplay disinfection procedures, eradication of the pathogen is often difficult. Hence, for prevention, good management practices coupled with vaccination of dam for protecting young ones, has to be practiced. Recently, new generation prophylactic strategies including DNA vaccines, subunit vaccines, virus-like particles (VLPs) and edible vaccines have been found to induce sufficient levels of passive immunity. Aside to the infection in animals, zoonotic significance of the animal rotaviruses has to be further unearthed. In this review, efforts have been made to highlight the importance and prevalence of the disease in bovines, its pathogenesis along with preventive measures, salient features of rotaviruses and their inter-species transmission abilities, zoonotic implications, and a concise account of the infection in various domestic animals and poultry.

Determination of human rotavirus VP6 genogroups I and II by reverse transcription-PCR

Based on nucleotide sequence and phylogenetic analysis of the partial VP6 genes, group A rotaviruses can be mainly differentiated into two genogroups. In this study, a method employing reverse transcription-PCR (RT-PCR) and degenerate primers was established to assign the VP6 genogroup. VP6 genogroup I and genogroup II could be determined according to the sizes of the amplicons: 380 and 780 bp, respectively. The VP6 genogroup of human reference strains of G1 to G4 and G9 types and RotaTeq vaccine strains could be properly assigned by RT-PCR. Eighty rotavirus-positive fecal samples were subjected to enzyme-linked immunosorbent assay (ELISA), RT-PCR, and sequencing of the partial VP6 gene for subgroup and genogroup determination. The results correlated well among these three methods, except for seven samples whose subgroups could not be determined by ELISA. VP6 genogroups of another 150 rotavirus strains recovered between 1981 and 2005 were determined by RT-PCR and sequencing, and the same results were obtained by these two methods. Furthermore, an additional 524 rotavirus-positive fecal samples were tested by RT-PCR, and the VP6 genogroups could be easily determined. The RT-PCR assay developed here provided a reliable and convenient method for assigning the VP6 genogroups of human rotaviruses with a wide range of genetic variation.

Full genome-based classification of rotaviruses reveals a common origin between human Wa-Like and porcine rotavirus strains and human DS-1-like and bovine rotavirus strains

Group A rotavirus classification is currently based on the molecular properties of the two outer layer proteins, VP7 and VP4, and the middle layer protein, VP6. As reassortment of all the 11 rotavirus gene segments plays a key role in generating rotavirus diversity in nature, a classification system that is based on all the rotavirus gene segments is desirable for determining which genes influence rotavirus host range restriction, replication, and virulence, as well as for studying rotavirus epidemiology and evolution. Toward establishing such a classification system, gene sequences encoding VP1 to VP3, VP6, and NSP1 to NSP5 were determined for human and animal rotavirus strains belonging to different G and P genotypes in addition to those available in databases, and they were used to define phylogenetic relationships among all rotavirus genes. Based on these phylogenetic analyses, appropriate identity cutoff values were determined for each gene. For the VP4 gene, a nucleotide identity cutoff value of 80% completely correlated with the 27 established P genotypes. For the VP7 gene, a nucleotide identity cutoff value of 80% largely coincided with the established G genotypes but identified four additional distinct genotypes comprised of murine or avian rotavirus strains. Phylogenetic analyses of the VP1 to VP3, VP6, and NSP1 to NSP5 genes showed the existence of 4, 5, 6, 11, 14, 5, 7, 11, and 6 genotypes, respectively, based on nucleotide identity cutoff values of 83%, 84%, 81%, 85%, 79%, 85%, 85%, 85%, and 91%, respectively. In accordance with these data, a revised nomenclature of rotavirus strains is proposed. The novel classification system allows the identification of (i) distinct genotypes, which probably followed separate evolutionary paths; (ii) interspecies transmissions and a plethora of reassortment events; and (iii) certain gene constellations that revealed (a) a common origin between human Wa-like rotavirus strains and porcine rotavirus strains and (b) a common origin between human DS-1-like rotavirus strains and bovine rotaviruses. These close evolutionary links between human and animal rotaviruses emphasize the need for close simultaneous monitoring of rotaviruses in animals and humans.

Development of a microtiter plate hybridization-based PCR-enzyme-linked immunosorbent assay for identification of clinically relevant human group A rotavirus G and P genotypes

A microtiter plate hybridization-based PCR-enzyme-linked immunosorbent assay (PCR-ELISA) has been used for the detection and identification of a variety of microorganisms. Here, we report the development of a PCR-ELISA for the identification of clinically relevant human rotavirus VP7 (G1 to G6, G8 to G10, and G12) and VP4 (P[4], P[6], P[8], P[9], and P[14]) genotypes. The G and P types of reference human and animal rotavirus strains for which specific probes were available were correctly identified by the PCR-ELISA. In addition, reference strains bearing G or P genotypes for which specific probes were unavailable, such as G11, G14, P[3], P[10], and P[11], did not display any cross-reactivity to the probes. The usefulness of the assay was further evaluated by analyzing a total of 396 rotavirus-positive stool samples collected in four countries: Brazil, Ghana, Japan, and the United States. The results of this study showed that the PCR-ELISA was sensitive and easy to perform without the use of any expensive and sophisticated equipment, the reagents used are easy to obtain commercially and advantageous over multiplex PCR since more than one type-specific probe is used and the selection of probes is more flexible.

Characterization of a G11,P[4] strain of human rotavirus isolated in South Korea

A novel human rotavirus strain, CUK-1, containing a G11 type combined with a P[4] type was isolated from a 1-year-old female patient with fever and severe diarrhea at Our Lady of Mercy Hospital in Incheon, South Korea. This CUK-1 strain showed the highest degree of nucleic acid similarity (98.7% and 93%) to G11 Dhaka6 and P[4] RV 5, respectively. This novel combined type of CUK-1 rotavirus strain (G11,P[4]) was uncovered from humans and is reported on here for the first time.

Development and validation of DNA microarray for genotyping group A rotavirus VP4 (P[4], P[6], P[8], P[9], and P[14]) and VP7 (G1 to G6, G8 to G10, and G12) genes

Previously, we reported the development of a microarray-based method for the identification of five clinically relevant G genotypes (G1 to G4 and G9) (V. Chizhikov et al., J. Clin. Microbiol. 40:2398-2407, 2002). The expanded version of the rotavirus microarray assay presented herein is capable of identifying (i) five clinically relevant human rotavirus VP4 genotypes (P[4], P[6], P[8], P[9], and P[14]) and (ii) five additional human rotavirus VP7 genotypes (G5, G6, G8, G10, and G12) on one chip. Initially, a total of 80 cell culture-adapted human and animal reference rotavirus strains of known P (P[1] to P[12], P[14], P[16], and P[20]) and G (G1-6, G8 to G12, and G14) genotypes isolated in various parts of the world were employed to evaluate the new microarray assay. All rotavirus strains bearing P[4], P[6], P[8], P[9], or P[14] and/or G1 to G6, G8 to G10, or G12 specificity were identified correctly. In addition, cross-reactivity to viruses of genotype G11, G13, or G14 or P[1] to P[3], P[5], P[7], P[10] to P[12], P[16], or P[20] was not observed. Next, we analyzed a total of 128 rotavirus-positive human stool samples collected in three countries (Brazil, Ghana, and the United States) by this assay and validated its usefulness. The results of this study showed that the assay was sensitive and specific and capable of unambiguously discriminating mixed rotavirus infections from nonspecific cross-reactivity; the inability to discriminate mixed infections from nonspecific cross-reactivity is one of the inherent shortcomings of traditional multiplex reverse transcription-PCR genotyping. Moreover, because the hybridization patterns exhibited by rotavirus strains of different genotypes can vary, this method may be ideal for analyzing the genetic polymorphisms of the VP7 or VP4 genes of rotaviruses.

Molecular analysis of the NSP4 and VP6 genes of rotavirus strains recovered from hospitalized children in Rio de Janeiro, Brazil

Group A rotaviruses are the main cause of acute gastroenteritis in children throughout the world. The two outer capsid proteins, VP4 and VP7, define the P and G genotypes, respectively. Rotaviruses with P[8]G1, P[4]G2, P[8]G3 and P[8]G4 genotypes are predominant in infecting humans and the G9 genotype is emerging in most continents as the fifth most common G type worldwide. The inner capsid protein VP6 is responsible for subgroup (SG) specificities, allowing classification of rotaviruses into SG I, SG II, SG I+II and SG non-I-non-II. The non-structural protein 4 (NSP4) encoded by segment 10 has a role in viral morphogenesis and five genetic groups have been described, NSP4 genotypes A–E. The aim of this investigation was to characterize the NSP4 and VP6 genes of rotavirus strains recovered from hospitalized children. Thirty rotavirus strains were submitted to RT-PCR followed by sequencing and phylogenetic analysis. Among the different G and P genotype combinations, two distinct genetic groups could be recognized for the NSP4 gene. Twenty-eight clustered with NSP4 genotype B. The two P[4]G2 strains fell into NSP4 genotype A and clustered distinctly, with a 100 % bootstrap value. The strains distinguished within a group were closely related to each other at the nucleotide and amino acid levels. A phylogenetic tree was constructed for the VP6 gene including the human strains RMC100, E210, Wa, US1205 and 1076, and the animal strains Gott, NCDV, SA-11, FI-14 and EW. This is the first report on Brazilian rotavirus strains describing NSP4 genotype A strains associated with VP6 SG I, and NSP4 genotype B strains associated with VP6 SG II.