Molecular epidemiology of group a rotavirus among children admitted to hospital in Salto, Uruguay, 2011-2012: First detection of the emerging genotype G12

Genetic diversity and evolution of G12P[6] DS-1-like and G12P[9] AU-1-like Rotavirus strains in Brazil

In the early 2000s, the global emergence of rotavirus (RVA) G12P[8] genotype was noted, while G12P[6] and G12P[9] combinations remained rare in humans. This study aimed to characterize and phylogenetically analyze three Brazilian G12P[9] and four G12P[6] RVA strains from 2011 to 2020, through RT-PCR and sequencing, in order to enhance our understanding of the genetic relationship between human and animal-origin RVA strains. G12P[6] strains displayed a DS-1-like backbone, showing a distinct genetic clustering. G12P[6] IAL-R52/2020, IAL-R95/2020 and IAL-R465/2019 strains clustered with 2019 Northeastern G12P[6] Brazilian strains and a 2018 Benin strain, whereas IAL-R86/2011 strain grouped with 2010 Northern G12P[6] Brazilian strains and G2P[4] strains from the United States and Belgium. These findings suggest an African genetic ancestry and reassortments with co-circulating American strains sharing the same DS-1-like constellation. No recent zoonotic reassortment was observed, and the DS-1-like constellation detected in Brazilian G12P[6] strains does not seem to be genetically linked to globally reported intergenogroup G1/G3/G9/G8P[8] DS-1-like human strains. G12P[9] strains exhibited an AU-1-like backbone with two different genotype-lineage constellations: IAL-R566/2011 and IAL-R1151/2012 belonged to a VP3/M3.V Lineage, and IAL-R870/2013 to a VP3/M3.II Lineage, suggesting two co-circulating strains in Brazil. This genetic diversity is not observed elsewhere, and the VP3/M3.II Lineage in G12P[9] strains seems to be exclusive to Brazil, indicating its evolution within the country. All three G12P[9] AU-1-like strains were closely relate to G12P[9] strains from Paraguay (2006-2007) and Brazil (2010). Phylogenetic analysis also highlighted that all South American G12P[9] AU-1-like strains had a common origin and supports the hypothesis of their importation from Asia, with no recent introduction from globally circulating G12P[9] strains or reassortments with local G12 strains P[8] or P[6]. Notably, certain genes in the Brazilian G12P[9] AU-1-like strains share ancestry with feline/canine RVAs (VP3/M3.II, NSP4/E3.IV and NSP2/N3.II), whereas NSP1/A3.VI likely originated from artiodactyls, suggesting a history of zoonotic transmission with human strains. This genomic data adds understanding to the molecular epidemiology of G12P[6] and G12P[9] RVA strains in Brazil, offering insights into their genetic diversity and evolution.

Molecular Characterization of Gastroenteric Viruses in Wastewater from Cities in Uruguay

Group A Rotavirus, Human Astrovirus, and Norovirus (RVA, HAstV, and NoV) are recognized as the major causative agents of acute gastroenteritis in children and adults worldwide. The aim of this study was to determine the prevalence and molecular epidemiology of RVA, HAstV, and NoV in wastewater from three cities in Uruguay. Thirty-six samples from Bella Unión, Salto, and Fray Bentos cities were analyzed using quantitative and qualitative PCR. RVA was the most frequently detected virus (50%), followed by HAstV (39%), NoV GII (36%), and NoV GI (25%). RVA strains were characterized as P[8] and G3 based on the VP4 and VP7 genes, respectively. Among NoV-positive samples, genotypes GI.2, GI.3, GI.5, GI.6, GI.7, GII.2, GII.6, and GII.4 were detected, and only one HAstV genotype (MLB1) was found. Our wastewater-based epidemiological approach provides a snapshot of the overall genetic diversity of these viruses in three cities of the Uruguay River basin during 2017-2018. These findings reinforce the importance of this environmental surveillance tool for monitoring epidemiological trends of enteric viruses circulating in the population, which can be used to guide public health intervention.

Comparison of the risk of infection of human rotavirus and astrovirus according to fishing and swimming activities at Las Cañas beach, Uruguay

AIMS

To estimate the risk of human Rotavirus (RV) and Astrovirus (HAstV) infections for swimmers and fishers at Las Cañas beach, Uruguay.

METHODS AND RESULTS

Surface water samples were collected monthly for one year. The dose response models used were β Poisson and ₁ F₁ hypergeometric for RV and HAstV, respectively. The probabilities of infection were calculated using a kernel density estimate to fitting the data and then sampling from this distribution (Monte Carlo simulation). The probability of RV infection for fishers was between 0 and 65% and for swimmers was between 0 and 50% (<18 years old) and between 0 and 38% (>18 years old). For HAstV, the probability of infection for fishers was between 0% and 45% and for swimmers was between 0 and 38% (<18 years old) and between 0 and 18% (>18 years old).

CONCLUSIONS

This study suggests that fishers are at higher risk of infection for both viruses when compared with swimmers mainly due to higher viral frequency and concentration at the site for fishing activities.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study highlights the different risk of infection for Rotavirus and Astrovirus, determined according to two popular activities such as swimming and fishing evidencing their negative impact in public health when contaminated waters are used mainly in developing countries like Uruguay.

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.

Genetic characterization of G12P[6] and G12P[8] rotavirus strains collected in six African countries between 2010 and 2014

BACKGROUND

G12 rotaviruses were first observed in sub-Saharan Africa in 2004 and since then have continued to emerge and spread across the continent and are reported as a significant human rotavirus genotype in several African countries, both prior to and after rotavirus vaccine introduction. This study investigated the genetic variability of 15 G12 rotavirus strains associated with either P[6] or P[8] identified between 2010 and 2014 from Ethiopia, Kenya, Rwanda, Tanzania, Togo and Zambia.

METHODS

The investigation was carried out by comparing partial VP7 and partial VP4 sequences of the African G12P[6] and G12P[8] strains with the available GenBank sequences and exploring the recognized neutralization epitopes of these strains. Additionally, Bayesian evolutionary analysis was carried out using Markov Chain Monte Carlo (MCMC) implemented in BEAST to estimate the time to the most recent ancestor and evolutionary rate for these G12 rotavirus strains.

RESULTS

The findings suggested that the VP7 and VP4 nucleotide and amino acid sequences of the G12 strains circulating in African countries are closely related, irrespective of country of origin and year of detection, with the exception of the Ethiopian strains that clustered distinctly. Neutralization epitope analysis revealed that rotavirus VP4 P[8] genes associated with G12 had amino acid sequences similar to those reported globally including the vaccine strains in RotaTeq and Rotarix. The estimated evolutionary rate of the G12 strains was 1.016 × 10^- 3 substitutions/site/year and was comparable to what has been previously reported. Three sub-clusters formed within the current circulating lineage III shows the diversification of G12 from three independent ancestries within a similar time frame in the late 1990s.

CONCLUSIONS

At present it appears to be unlikely that widespread vaccine use has driven the molecular evolution and sustainability of G12 strains in Africa. Continuous monitoring of rotavirus genotypes is recommended to assess the long-term impact of rotavirus vaccination on the dynamic nature of rotavirus evolution on the continent.

Detection, Quantification, and Microbial Risk Assessment of Group A Rotavirus in Rivers from Uruguay

The aim of this study was to detect, quantify, and assess the risk of infection and illness for Group A Rotavirus (RVA) in the watersheds of the Santa Lucia and Uruguay rivers in Uruguay. Monthly sampling was carried out for one year in six sites in the watershed of the Santa Lucía River and four in the Uruguay River. All the collection sites are used for recreational activities. Viral concentration was performed with the adsorption-elution method, and detection and quantification of RVA was carried out by TaqMan quantitative PCR (qPCR). Quantitative microbial risk assessment was applied to estimate the daily and annual risk of RVA infection, as well as the daily risk of illness considering direct exposure through recreational activity. RVA was detected in 42% (20/48) of the analyzed samples in the Uruguay River and 40% (29/72) in the Santa Lucía River. The virus was present in all the analyzed points in both watersheds. A pattern of seasonality, characterized by a higher detection frequency of the virus during coldest month of the year, was observed in both basins. The mean concentration for RVA was 1.3 × 10⁵ genomic copies/L. The microbiological risk assessment shows that Santa Lucía watershed presented the highest daily risk of infection (6.41E-01) and illness (3.20E-01) estimated for the point downstream of Florida City; meanwhile for Uruguay River, the highest probabilities of infection (6.82E-01) and illness (3.41E-01) were estimated for the collection site for drinking water intake in Salto city. These results suggest that RVA contamination of these important rivers negatively impact on their microbiological quality since they are used for recreation and drinking water intake, demonstrating that the disposal of waste from cities located in their riverside confers a constant threat of infection for the general population, especially for children.

Modeling the Transport of Human Rotavirus and Norovirus in Standardized and in Natural Soil Matrix-Water Systems

We modeled Group A Rotavirus (RVA) and Norovirus genogroup II (GII NoV) transport experiments in standardized (crystal quartz sand and deionized water with adjusted pH and ionic strength) and natural soil matrix-water systems (MWS). On the one hand, in the standardized MWS, Rotavirus and Norovirus showed very similar breakthrough curves (BTCs), showing a removal rate of 2 and 1.7 log₁₀, respectively. From the numerical modeling of the experiment, transport parameters of the same order of magnitude were obtained for both viruses. On the other hand, in the natural MWS, the two viruses show very different BTCs. The Norovirus transport model showed significant changes; BTC showed a removal rate of 4 log₁₀, while Rotavirus showed a removal rate of 2.6 log₁₀ similar to the 2 log₁₀ observed on the standardized MWS. One possible explanation for this differential behavior is the difference in the isoelectric point value of these two viruses and the increase of the ionic strength on the natural MWS.

Spread of the emerging equine-like G3P[8] DS-1-like genetic backbone rotavirus strain in Brazil and identification of potential genetic variants

In 2013, the equine-like G3P[8] DS-1-like rotavirus (RVA) strain emerged worldwide. In 2016, this strain was reported in northern Brazil. The aims of the study were to conduct a retrospective genetic investigation to identify the possible entry of these atypical strains in Brazil and to describe their distribution across a representative area of the country. From 2013 to 2017, a total of 4226 faecal samples were screened for RVA by ELISA, PAGE, RT-PCR and sequencing. G3P[8] represented 20.9 % (167/800) of all RVA-positive samples, further subdivided as equine-like G3P[8], DS-1-like (11.0 %; 88/800) and Wa-like G3P[8] (9.9 %; 79/800). Six equine-like G3P[8] DS-1-like samples were selected for whole-genome investigation, confirming the backbone I2-R2-C2-M2-A2-N2-T2-E2-H2. During 2013-2014, Wa-like G3P[8] was predominant and no equine-like G3P[8] DS-1-like was detected. Equine-like G3P[8] DS-1-like was first identified in Paraná in March/2015, suggesting that the strain entered Brazil through the Southern region. Equine-like G3P[8] rapidly spread across the area under surveillance and displayed a marked potential to replace Wa-like G3P[8] strains. Brazilian equine-like G3P[8] DS-1-like strains clustered with contemporary equine-like G3P[8] DS-1-like detected worldwide, but exhibited a distinct NSP2 genotype (N2) compared to the previously reported Amazon equine-like G3P[8] DS-1-like strain (N1). Two distinct NSP4 E2 genotype lineages were also identified. Taken together, these data suggest that different variants of equine-like G3P[8] DS-1-like strains might have been introduced into the country at distinct time points, and co-circulated in the period 2015-2017. The global emergence of equine-like G3P[8] DS-1-like strains, predominantly in countries using the Rotarix vaccine, raises the question of whether vaccines may be inducing selective pressures on zoonotic strains.

Evaluation of Bacterial Contamination as an Indicator of Viral Contamination in a Sedimentary Aquifer in Uruguay

In Uruguay, groundwater is frequently used for agricultural activities, as well as for human consumption in urban and rural areas. As in many countries worldwide, drinking water microbiological quality is evaluated only according to bacteriological standards and virological analyses are not mentioned in the legislation. In this work, the incidence of human viral (Rotavirus A, Norovirus GII, and human Adenovirus) and bacterial (total and thermotolerant coliform and Pseudomonas aeruginosa) contamination in groundwater in the Salto district, Uruguay, as well as the possible correlation between these groups of microorganisms, was studied. From a total of 134 groundwater samples, 42 (32.1%) were positive for Rotavirus, only 1 (0.7%) for both Rotavirus and Adenovirus, and 96 (72.6%) samples were positive for bacterial indicators. Results also show that Rotavirus presence was not associated with changes in chemical composition of the aquifer water. Bacteriological indicators were not adequate to predict the presence of viruses in individual groundwater samples (well scale), but a deeper spatial-temporal analysis showed that they are promising candidates to assess the viral contamination degree at aquifer scale, since from the number of wells with bacterial contamination the number of wells with viral contamination could be estimated.

A one-step real-time RT-PCR helps to identify mixed rotavirus infections in Mexico

Rotaviruses continue being the most important pathogens responsible of diarrhea in young children worldwide. Seminested reverse transcription polymerase chain reaction (RT-PCR) is used to determine rotavirus genotype; however, this technique employs multistep procedures. The real-time RT-PCR is a fast and reliable tool that can be used as rotavirus genotyping tool, especially in rotavirus outbreaks. In this study, we tested a real-time RT-PCR to identify rotavirus genotype using a panel of 252 samples from patients with diarrheal disease caused by G9P[4] and G12P[8] genotypes, which were identified as emerging rotaviruses in 2 outbreaks in Chiapas, Mexico. Our results show that the real-time RT-PCR assay detected these rotaviruses, and it allowed us to identify mixed genotype infections, G/P combinations, and the viral abundance in some samples in which the seminested assay could not identify them. Therefore, the real-time RT-PCR is a molecular tool that can be great support during rotavirus outbreaks.

Resurgence of Rotavirus Genotype G12 in St. Louis During the 2014-2015 Rotavirus Season

BACKGROUND

Rotaviruses are a leading cause of gastroenteritis. Rotavirus vaccination has dramatically reduced rotavirus occurrence; however, we have noticed mild to moderate recurrences in the St. Louis area in alternate years. In 2013, we found rotavirus genotype G12 to be the dominant strain in the St. Louis region. In this study, we again determined the distribution of genotypes and ascertained vaccine history in patients infected with rotavirus G12 during the 2014-15 season.

METHODS

Samples submitted to the St. Louis Children's Hospital Microbiology Laboratory were tested for rotavirus using an antigen assay. We determined the VP7 genotype using amplicon sequence analysis. We determined genome sequences using high-throughput sequencing. We evaluated rotavirus immunization records when available.

RESULTS

Of 30 typed viruses from 2014-15, 29 were G12 (97%). Whole-genome sequencing revealed few changes from G12 viruses analyzed in 2012-13. VP4 and VP7 sequences were >99% identical to previously sequenced G12 strains from St. Louis, and immune epitopes were conserved. Vaccination histories were available from 17 patients. Of these, 4 had been vaccinated, 3 had received incomplete vaccination or had a vaccine history that could not be confirmed, and 10 had not been vaccinated.

CONCLUSIONS

G12 re-emerged as the predominant rotavirus genotype in 2014-15, comprising a higher percentage of cases than in 2012-13. The majority of patients with G12 and available vaccination histories were unvaccinated. There was no genomic evidence to indicate that the G12 strains in St. Louis had evolved to escape vaccine protection. Our work emphasizes the need for continued surveillance.

Epidemiology and genetic diversity of classic human astrovirus among hospitalized children with acute gastroenteritis in Uruguay

Classic Human Astrovirus (Classic HAstV) are one of the most important causes of pediatric acute gastroenteritis (AGE), after rotaviruses and arguably caliciviruses. The aim of this study was to determine the molecular epidemiology of Classic HAstV from 175 clinical samples, being 153 stools and 22 vomits, collected from pediatric hospitalized patients with AGE in Salto city, Uruguay, from January 2011 to December 2012. Classic HAstV were detected and genotyped by using a qualitative Retro Transcription-Polimerase Chain Reaction (RT-PCR) directed to the Open Reading Frame-2 (ORF2) region C. Amplicons were sequenced and phylogenetic analyses were carried out in order to determine genotypes and lineages. Classic HAstV were detected in 18 out of 175 analyzed samples (10.3%) and 14 of them (78.0%) were successfully sequenced being 6 (42.8%) classified as HAstV-1 (1a lineage), 4 (28.6%) as HAstV-2 (2c lineage), and 4 (28.6%) as HAstV-3 (3c lineage). A higher detection of Classic HAstV infections was observed in autumn for both years of surveillance, and the majority of the positive cases were observed in 2011. The group of children between 2 and 5 years old presented the higher percentage of infections. To our knowledge, the present study represents the first report of astrovirus from acute gastroenteritis cases in Uruguay, evidencing its role as a relevant etiologic agent in severe cases of this disease.

VP7 and VP8* genetic characterization of group A rotavirus genotype G12P[8]: Emergence and spreading in the Eastern Brazilian coast in 2014

Group A rotavirus (RVA) genotype G12 is habitually associated with diarrhea disease (DD) in African children and recently its detection has increased worldwide. A total of 970 stool samples collected from individuals with DD in the Northeastern, Southeastern, and Southern Brazilian regions, Eastern coast, were analyzed and 321 (33%) were positive for RVA and of these, 241 (75%) genotyped as G12P[8]. The rate of RVA positivity was higher among children aged 5-10 years old (60%). All RVA infections observed in adults aged >21 years were G12P[8] (n = 27) showing that this genotype affected older age groups during the year of 2014 in Brazil. Phylogenetic analysis of VP7 and VP8* G12P[8] strains demonstrated an elevated similarity among Brazilian and G12-III prototypes strains circulating worldwide recently, suggesting that this lineage is associated with the global spread of the G12 genotype, considered as the 6th most prevalent human RVA genotype nowadays; while other G12 lineages remain sporadically detected and usually detected in association with other P genotypes. VP8* analysis revealed that Brazilian strains belong to P[8]-3 lineage, the single P[8] lineage presently detected in the country. No major nucleotide/amino acid disparities were observed among strains recovered from children and adults for VP7 and VP8* genes. These data are essential to support the surveillance studies, particularly in countries where the RVA vaccine was introduced in their National Immunization Program enabling identification of potential alterations in the epidemiological profile that can impact its efficacy in vaccination programs. J. Med. Virol. 89:64-70, 2017. © 2016 Wiley Periodicals, Inc.

Detection of the emerging rotavirus G12P[8] genotype at high frequency in brazil in 2014: Successive replacement of predominant strains after vaccine introduction

The continuum characterization of rotavirus (RVA) genotypes is essential to understand how vaccine introduction could impact virus epidemiology. In the present study, an unexpected rapid changing pattern of RVA genotypes distribution in Brazilian population during three followed seasons is described. From January/2012 to December/2014, a total of 3441 fecal specimens were collected from collaborating centers across Southern, Southeastern and Midwest of Brazil. All specimens were screened for RVA using ELISA, and genotyped by RT-PCR. Differences in proportions were tested using Chi-Squares. A p-value of less than 0.05 was considered statistically significant. RVA was detected in 19.7% (677/3441). Among RVA positive cases (n=677), a total of 652 (96.3%) samples were successfully amplified by RT-PCR. G3P[8] remained prevalent in 2012 (37.6%, 69/185) and 2013 (40.1%, 74/186) (χ(2)=0.107, p=0.743), but declined markedly in 2014 (3.5%, 10/281) (χ(2)=71.770, p=0.000). G12P[8] was second highest strain in 2012 (22.7%, 42/185), decrease rapidly in 2013 (2.7%, 5/186) (χ(2)=26.224, p=0.000) and re-emerged as the predominant genotype in 2014 (86.6%, 243/281) (χ(2)=118.299, p=0.000). From July/2014, G12P[8] was the single genotype detected in all regions studied. The sudden emergence, spread and predominance of G12P[8] strain in Brazil, raised the hypothesis of a possible G12 outbreak being in progress. Nationally, the long term decline in gastroenteritis hospitalization observed in the country after RVA vaccine introduction was confirmed. Nevertheless, the sharp increase in diarrhea hospitalization prevalence from 2013 to 2014 observed in Southern and Southeastern regions is consistent with what appears to be an outbreak of G12P[8]. Continued surveillance is needed to verify the effectiveness of the RotarixTM vaccine in Brazil together with potential emergence of unusual genotypes.

Detection of Common, Emerging and Uncommon VP4, and VP7 Human Group A Rotavirus Genotypes from Urban Sewage Samples in Uruguay

Environmental approach has proven to be a useful tool for epidemiological studies demonstrating through environmental studies the diversity of viruses circulating in a given population. The aim of this study was to perform a phylogenetic characterization of the group A rotavirus (RVA) glycoprotein (G)- and protease-sensitive (P)-genotypes obtained from sewage samples (n = 116) collected in six cities of Uruguay during March 2011 to April 2013. A worldwide standardized semi-nested multiplex RT-PCR (SNM RT-PCR) protocol directed against VP4 and VP7 genes were conducted for RVA detection and consensual DNA fragments were submitted to nucleotide sequencing. P and/or G genotype was successfully determined by phylogenetic analysis in 61% (n = 37) of the positive samples obtained by SNM RT-PCR (n = 61). The RVA genotypes were as follow: G1 (n = 2), G2 (n = 14), G3 (n = 5), G12 (n = 2), P[4] (n = 4), P[8] (n = 16), and P[3] (n = 2). Interestingly, through phylogenetic analysis, emerging, and uncommon human genotypes could be detected. Results obtained from the comparison of RVA genotypes detected in the current study and Uruguayan RVA strains previously described for contemporary clinical pediatric cases showed that monitoring sewage may be a good screening option for a rapid and economical overview of the circulating genotypes in the surrounding human population and a useful approximation to study RVA epidemiology in a future vaccine monitoring program. The present study represents the first report in Uruguay that describes the phylogenetic diversity of RVA from urban sewage samples.

Burden of Norovirus and Rotavirus in Children After Rotavirus Vaccine Introduction, Cochabamba, Bolivia

The effectiveness of rotavirus vaccine in the field may set the stage for a changing landscape of diarrheal illness affecting children worldwide. Norovirus and rotavirus are the two major viral enteropathogens of childhood. This study describes the prevalence of norovirus and rotavirus 2 years after widespread rotavirus vaccination in Cochabamba, Bolivia. Stool samples from hospitalized children with acute gastroenteritis (AGE) and outpatients aged 5-24 months without AGE were recruited from an urban hospital serving Bolivia's third largest city. Both viruses were genotyped, and norovirus GII.4 was further sequenced. Norovirus was found much more frequently than rotavirus. Norovirus was detected in 69/201 (34.3%) of specimens from children with AGE and 13/71 (18.3%) of those without diarrhea. Rotavirus was detected in 38/201 (18.9%) of diarrheal specimens and 3/71 (4.2%) of non-diarrheal specimens. Norovirus GII was identified in 97.8% of norovirus-positive samples; GII.4 was the most common genotype (71.4% of typed specimens). Rotavirus G3P[8] was the most prevalent rotavirus genotype (44.0% of typed specimens) and G2P[4] was second most prevalent (16.0% of typed specimens). This community is likely part of a trend toward norovirus predominance over rotavirus in children after widespread vaccination against rotavirus.

High prevalence of G12P[8] rotavirus strains in Rio Branco, Acre, Western Amazon, in the post-rotavirus vaccine introduction period

The present study aimed to provide a molecular characterization of circulating rotavirus (RVA) strains in Rio Branco, Acre, in the post-rotavirus vaccination period, particularly with regard to the emerging, increasingly prevalent G12P[8] genotype. A total of 488 fecal specimens from diarrheic and non-diarrheic children were obtained between January and December 2012. RVA detection was initially performed using enzyme-linked immunosorbent assay (ELISA) method, followed by reverse-transcription polymerase chain reaction (RT-PCR) using specific primers. RVA was detected in 18.3% (44/241) of the children with acute diarrhea and in 1.2% (3/247) of the non-diarrheic children (P < 0.001), with overall RVA-positivity of 9.6% (47/488). The most common genotype was G2P[4] with 43.2% (19/44) of the diarrheic cases, followed by G12P[8] (27.3%, 12/44), G3P[6] (18.2%, 8/44), G3P[8] (4.5%, 2/44), and G12P[6] (2.3%, 1/44). G12 samples belonged to lineage III and were from children aged 4-52 months. All of these children had acute diarrhea associated with fever (83.3%, 10/12) and vomiting (66.7%, 8/12). Most of the cases occurred in August (58.3%, 7/12), 75% (9/12) of which having received the full vaccination scheme with Rotarix™. For the first time G12 was reported at relative high prevalence in Brazil. Our findings warrant further monitoring studies on the molecular characterization of circulating RVA strains after rotavirus vaccine introduction in Brazil and elsewhere, since the occurrence of either unusual our emerging genotypes may pose a challenge to vaccination strategies.

Impact of vaccination on the molecular epidemiology and evolution of group A rotaviruses in Latin America and factors affecting vaccine efficacy

Despite high rotavirus (RV) vaccine coverage (∼83%) and good effectiveness (∼77%) against RV-diarrhea hospitalization, RV is still contributing to the burden of diarrhea that persists in hospital settings in several Latin American countries, where RV vaccination is being implemented. Due to the extensive genomic and antigenic diversity, among co-circulating human RV, a major concern has been that the introduction of RV vaccination could exert selection pressure leading to higher prevalence of strains not included in the vaccines and/or emergence of new strains, thus, reducing the efficacy of vaccination. Here we review the molecular epidemiology of RV in Latin America and explore issues of RV evolution and selection in light of vaccination. We further explore etiologies behind the large burden of diarrhea remaining after vaccination in some countries and discuss plausible reasons for vaccine failures.