Diversity Of Noroviruses Research Articles

Characterization of cross-reactive, non-neutralizing monoclonal antibodies against a pandemic GII.4 norovirus variant.

To gain insights into the overall immune responses to human norovirus, we characterized non-neutralizing, cross-reactive monoclonal antibodies (mAbs) developed against a pandemic GII.4 norovirus. We determined the binding epitope of an antibody that exhibited cross-reactivity against all tested noroviruses, which makes it a useful tool for research and diagnostics. The epitope of two additional non-neutralizing mAbs was mapped to a less conserved region on the viral capsid protein, explaining their cross-reactivity patterns. Often overlooked, the role of non-neutralizing, cross-reactive mAbs merits further research to facilitate our understanding of immunity to norovirus infection and disease.

Long Amplicon Nanopore Sequencing for Dual-Typing RdRp and VP1 Genes of Norovirus Genogroups I and II in Wastewater

Noroviruses (NoVs) are the leading cause of non-bacterial gastroenteritis with societal costs of US$60.3 billion per annum. Development of a long amplicon nanopore-based method for dual-typing the RNA-dependent RNA polymerase (RdRp) and major structural protein (VP1) regions from a single RNA fragment could improve existing norovirus typing methods. Application to wastewater-based epidemiology (WBE) and environmental testing could enable the discovery of novel types and improve outbreak tracking and source apportionment. Here, we have developed such a method with a consensus-based bioinformatics pipeline and optimised reverse transcription (RT) and PCR procedures. Inhibitor removal and LunaScript® RT gave robust amplification of the ≈ 1000 bp RdRP + VP1 amplicon for both the GI and GII PCR assays. Platinum™ Taq polymerase showed good sensitivity and reduced levels non-specific amplification (NSA) when compared to other polymerases. Optimised PCR annealing temperatures significantly reduced NSA (51.3 and 42.4% for GI and GII), increased yield (86.5% for GII) and increased taxa richness (57.7%) for GII. Analysis of three NoV positive faecal samples showed 100% nucleotide similarity with Sanger sequencing. Eight GI genotypes, 11 polymerase types (p-types) and 13 combinations were detected in wastewater along with 4 GII genotypes, 4 p-types and 8 combinations; highlighting the diversity of norovirus taxa present in wastewater in England. The most common genotypes detected in clinical samples were all detected in wastewater while we also frequently detected several GI genotypes not reported in the clinical data. Application of this method into a WBE scheme, therefore, may allow for more accurate measurement of norovirus diversity within the population.

Identification of Enteric Pathogen Reservoirs and Transmission Pathways Associated with Short Childhood Stature in the Kolkata Indian Site of the Global Enteric Multicenter Study.

Age-stratified path analyses modeled associations between enteric pathogen reservoirs, transmission pathways and height-for-age z-scores (HAZ) to identify determinants of childhood growth in the Kolkata, India site of the Global Enteric Multicenter Study (GEMS). Models tested direct associations of potential pathogen reservoirs with HAZ at 60-day follow-up in separate moderate and severe diarrhea (MSD) case and control cohorts or indirectly when mediated by enteric infections. In the MSD cohort, rotavirus and typical EPEC (tEPEC) infections among children 0-11 months of age and ST-ETEC infections among children 12-23 months of age were associated with lower HAZ. Handwashing after defecating and before cooking reduced impaired growth through reductions in rotavirus and tEPEC infections. Water storage increased rotavirus and ST-ETEC infection risks, resulting in increased impaired growth, but was reduced with reported child feces disposal. The GII norovirus variant was inversely associated with HAZ among children 12-59 months of age in the control cohort. Reported handwashing before the handling of children reduced GII infections and impaired growth. Boiling water and the disposal of children's feces mediated by stored water were positively associated with HAZ. The targeting of pathogen-specific reservoirs and transmission pathways may more effectively improve childhood linear growth in South Asian urban communities.

The viral trends and genotype diversity of norovirus in the wastewater of Shenzhen, China

Norovirus (NoV) is the primary cause of acute gastroenteritis (AGE) on a global scale. Numerous studies have demonstrated the immense potential of wastewater surveillance in monitoring the prevalence and spread of NoV within communities. This study employed a one-step reverse transcription-quantitative PCR to quantify NoV GI/GII in wastewater samples (n = 2574), which were collected once or twice a week from 38 wastewater treatment plants from March 2023 to February 2024 in Shenzhen. The concentrations of NoV GI and GII ranged from 5.0 × 104 to 1.7 × 106 copies/L and 4.1 × 105 to 4.5 × 106 copies/L, respectively. The concentrations of NoV GII were higher than those of NoV GI. Spearman's correlation analysis revealed a moderate correlation between the concentration of NoV in wastewater and the detection rates of NoV infections in sentinel hospitals. Baseline values were established for NoV concentrations in Shenzhen's wastewater, providing a crucial reference point for implementing early warning systems and nonpharmaceutical interventions to mitigate the impact of potential outbreaks. A total of 24 NoV genotypes were identified in 100 wastewater samples by sequencing. Nine genotypes of NoV GI were detected, with the major genotypes being GI.4 (38.6 %) and GI.3 (21.8 %); Fifteen genotypes of NoV GII were identified, with GII.4 (53.6 %) and GII.17 (26.0 %) being dominant. The trends in the relative abundance of NoV GI/GII were significantly different, and the trends in the relative abundance of NoV GII.4 over time were similar across all districts, suggesting a potential risk of cross-regional spread. Our findings underscore the effectiveness of wastewater surveillance in reflecting population-level NoV infections, capturing the diverse array of NoV genotypes, and utilizing NoV RNA in wastewater as a specific indicator to supplement clinical surveillance data, ultimately enhancing our ability to predict the timing and intensity of NoV epidemics.

Molecular Epidemiology of Human Norovirus Variants from Outbreaks in Zhejiang Province, China, during 2021

Molecular Epidemiology of Human Norovirus Variants from Outbreaks in Zhejiang Province, China, during 2021

Genetic diversity and distribution of noroviruses among all age groups of patients with diarrhea in Amhara National Regional State, Ethiopia.

Norovirus (NoV) is the leading cause of diarrheal disease worldwide and the impact is high in developing countries, including Ethiopia. Moreover, there is a significant and fluctuating global genetic diversity that varies across diverse environments over time. Nevertheless, there is a scarcity of data on the genetic diversity of NoV in Ethiopia. This study was aimed to assess the genetic diversity and distribution of NoVs circulating in the Amhara National Regional State, Ethiopia, by considering all age groups. A total of 519 fecal samples were collected from diarrheal patients from May 01/2021 to November 30/ 2021. The fecal samples were screened for the presence of NoVs using real-time RT-PCR by targeting a portion of the major capsid protein coding region. The positive samples were further amplified using conventional RT-PCR, and sequenced. The positivity rate of NoV was (8.9%; 46/519). The detection rate of NoV genogroup II (GII) and genogroup I (GI) was 38 (82.6%) and 8 (17.4%), respectively. Overall, five distinct GII (GII.3, GII.6, GII.10, GII.17, and GII.21) and two GI (GI.3 and GI.5) genotypes were detected. Within the GII types, GII.3 was the predominant (34.2%) followed by GII.21 (15.8%), GII.17 (10.5%), GII.6 and GII.10 each (2.6%). Norovirus GII.21 is reported for the first time in Ethiopia. The genetic diversity and distribution of NoVs were significantly different across the four sampling sits and age groups. The phylogenetic analysis revealed close relatedness of the current strains with published strains from Ethiopia and elsewhere. The distribution and genetic diversity of NoV was considerably high, with predominance of non-GII.4 genotypes. The GII.21 genotype is a new add on the growing evidences on the genetic diversity of NoVs in Ethiopia. Future nationwide surveillance studies are necessary to gain comprehensive data in Ethiopia.

Molecular epidemiology and genetic diversity of norovirus among hospitalized patients with acute gastroenteritis in Shandong, China, 2016-2018.

Norovirus (NoV) infection is a leading cause of acute gastroenteritis (AGE) for people of all ages. Here, we reported the molecular epidemiology and genetic diversity of NoVs among hospitalized patients with AGE between 2016 and 2018 in Shandong Province, China. Two thousand sixty-nine AGE patients from sentinel hospitals were enrolled. The stool samples were collected and tested for NoVs by real-time RT-PCR. The RNA-dependent RNA polymerase (RdRp) and capsid gene of 163 strains were amplified and sequenced for genotyping. Phylogenetic analyses and genomic characterization were conducted with the VP1 and RdRp region of the full genome sequences. Four hundred seventy two(21.76%) samples were NoV-positive. The positive rate in 2016 was higher than those of 2017 and 2018. We observed diverse NoV genotypes. GII.2[P16] emerged in January 2017 and became the dominant genotype between May and June 2017. Phylogenetic analyses showed that our GII.2[P16] genomes clustered in the SC1 in VP1 region, while they belonged to the Emerging GⅡ.P16 (2015-2017) clade in RdRp region. Our GⅡ.4 strains displayed two amino acid mutations, positions R297H and D372N, in epitope A of the VP1 region. Our study highlighted that NoV is an important pathogen of viral AGE in Shandong and, therefore, it is necessary to strengthen its surveillance.

Norovirus evolves as one or more distinct clonal populations in immunocompromised hosts.

Noroviruses are an important cause of chronic diarrhea in patients with compromised immune systems. Presently, there are no effective therapies to clear the virus, which can persist for years in the intestinal tract. The goal of our study was to develop a better understanding of the norovirus strains that are associated with these long-term infections. With the remarkable diversity of norovirus strains detected in the immunocompromised patient cohort we studied, it appears that most, if not all, noroviruses circulating in nature may have the capacity to establish a chronic infection when a person is unable to mount an effective immune response. Our work is the most comprehensive genetic data set generated to date in which near full-length genomes from noroviruses associated with chronic infection were analyzed by high-resolution next-generation sequencing. Analysis of this data set led to our discovery that certain patients in our cohort were shedding noroviruses that could be subdivided into distinct haplotypes or populations of viruses that were co-evolving independently. The ability to track haplotypes of noroviruses during chronic infection will allow us to fine-tune our understanding of how the virus adapts and maintains itself in the human host, and how selective pressures such as antiviral drugs can affect these distinct populations.

Emergence of GII.4 Sydney[P16]-like Norovirus-Associated Gastroenteritis, China, 2020-2022.

Newly evolved GII.4 Sydney[P16] norovirus with multiple residue mutations, already circulating in parts of China, became predominant and caused an abrupt increase in diagnosed norovirus cases among children with gastroenteritis in Shanghai during 2021-2022. Findings highlight the need for continuous long-term monitoring for GII.4 Sydney[P16] and emergent GII.4 norovirus variants.

Fucose Binding Cancels out Mechanical Differences between Distinct Human Noroviruses.

The majority of nonbacterial gastroenteritis in humans and livestock is caused by noroviruses. Like most RNA viruses, frequent mutations result in various norovirus variants. The strain-dependent binding profiles of noroviruses to fucose are supposed to facilitate norovirus infection. It remains unclear, however, what the molecular mechanism behind strain-dependent functioning is. In this study, by applying atomic force microscopy (AFM) nanoindentation technology, we studied norovirus-like particles (noroVLPs) of three distinct human norovirus variants. We found differences in viral mechanical properties even between the norovirus variants from the same genogroup. The noroVLPs were then subjected to fucose treatment. Surprisingly, after fucose treatment, the previously found considerable differences in viral mechanical properties among these variants were diminished. We attribute a dynamic switch of the norovirus P domain upon fucose binding to the reduced differences in viral mechanical properties across the tested norovirus variants. These findings shed light on the mechanisms used by norovirus capsids to adapt to environmental changes and, possibly, increase cell infection. Hereby, a new step towards connecting viral mechanical properties to viral prevalence is taken.

Development of enhanced primer sets for detection of Norovirus and Hepatitis A in food samples from Guayaquil (Ecuador) by reverse transcriptase-heminested PCR

Norovirus (NV) is an infectious biological agent that causes gastrointestinal problems of the original nonbacterial appearance of foodborne illnesses. The genotype of NV responsible for the most frequent NV disease outbreaks is GII, accounting for 60–80% of the cases. Moreover, original and new NV variants are continuously emerging, concurrent with the recent global increase in NV infections. Hepatitis A virus (HAV) is another foodborne pathogen frequently implicated in acute gastroenteritis cases around the world. The virus is transmitted among humans via the fecal-oral route, and infection by HAV causes the most severe form of viral illness acquired from foods. In this study, we implemented primer sets to detect NV genotypes I and II. We also developed primer sets for the detection of HAV. The primers were used in a heminested reverse transcriptase PCR (hnRT-PCR) protocol that was rapid and sensitive for detecting NVG1, NVGII and HAV virus in food. The hnRT-PCR was applied successfully to strawberries and spinach obtained from a local fresh-food market, where we could see NVGI, NVGII and HAV. Keywords: Norovirus1; Hepatitis A2; gastroenteritis3; genotypes4; NVG15; NVGII6; hnRT-PCR7.

High prevalence of norovirus GII.4 Sydney among children with acute gastroenteritis in Bangladesh, 2018–2021

BackgroundActive molecular surveillance and rapid diagnosis method to track an outbreak of norovirus in Bangladesh is lacking. This study aims to determine the genotypic diversity, molecular epidemiology and evaluate a rapid diagnosis method. MethodsA total of 404 fecal specimens were collected from children aged below 60 months from January 2018 to December 2021. All samples were analyzed by reverse transcriptase polymerase chain reaction molecular sequencing of partial VP1 nucleotide. Immunochromatography kit (IC, IP Rota/Noro) was evaluated against reference test method. ResultsWe found norovirus in 6.7 % (27 of 404) fecal specimens. A wide diversity of norovirus genotype including GII.3, GII.4, GII.5, GII.6, GII.7, and GII.9 were detected. Norovirus strain GII.4 Sydney-2012 was the most predominant (74 %, 20 of 27) followed by GII.7 (7.4 %), GII.9 (7.4 %), GII.3 (3.7 %), GII.5 (3.7 %) and GII.6 (3.7 %), respectively. Co-infection of rotavirus and norovirus (19 [4.7 %] of 404) was the most prevalent. We found higher odds of prolonged health impact [OR 1.93 (95 % CI 0.87–3.12) (p = .001)] among patients with co-infection. The incidence of norovirus was significant among the children below 24 months (p = 0.001). Significant relation of temperature with the cases of norovirus was detected (p = 0.001). The IC kit provided high specificity (99.3 %) and sensitivity (100 %) for the detection of norovirus. ConclusionsThis study will provide an integrated insight on the genotypic diversity and rapid identification method of norovirus in Bangladesh.

Epidemiology and genetic diversity of norovirus GII genogroups among children in Hubei, China, 2017–2019

Norovirus (NoV) is an important cause of viral acute gastroenteritis (AGE). To gain insights into the epidemiological characteristics and genetic diversity of NoV among children in Hubei, 1216 stool samples from children (≤ 5 years) obtained under AGE surveillance from January 2017 to December 2019 were analyzed. The results showed that NoV was responsible for 14.64% of AGE cases, with the highest detection rate in children aged 7–12 months (19.76%). Statistically significant differences were found between male and female infection rates (χ2 ​= ​8.108, P ​= ​0.004). Genetic analysis of RdRp and VP1 sequences showed that NoV GII genotypes were GII.4 Sydney [P31] (34.35%), GII.3 [P12] (25.95%), GII.2 [P16] (22.90%), GII.4 Sydney [P16] (12.98%), GII.17 [P17] (2.29%), GII.6 [P7] and GII.3 [P16] (each at 0.76%). GII.17 [P17] variants were divided into the Kawasaki323-like lineage and the Kawasaki308-like lineage. A unique recombination event was detected between strains of GII.4 Sydney 2012 and GII.4 Sydney 2016. Significantly, all GII.P16 sequences associated with GII.4/GII.2 obtained in Hubei were correlated with novel GII.2 [P16] variants that re-emerged in Germany in 2016. Antigenic site analysis of complete VP1 sequences from all GII.4 variants from Hubei identified notable variable residues of antibody epitopes. Genotyping under continuous AGE surveillance and observation of the antigenic sites of VP1 are important monitoring strategies for emerging NoV strains.

Development of enhanced primer sets for detection of Norovirus and Hepatitis A in food samples from Guayaquil (Ecuador) by reverse transcriptase-heminested PCR

Norovirus (NV) is an infectious biological agent that causes gastrointestinal problems of the original nonbacterial appearance of foodborne illnesses. The genotype of NV responsible for the most frequent NV disease outbreaks is GII, accounting for 60–80% of the cases. Moreover, original and new NV variants are continuously emerging, concurrent with the recent global increase in NV infections. Hepatitis A virus (HAV) is another foodborne pathogen frequently implicated in acute gastroenteritis cases around the world. The virus is transmitted among humans via the fecal-oral route, and infection by HAV causes the most severe form of viral illness acquired from foods. In this study, we implemented primer sets to detect NV genotypes I and II. We also developed primer sets for the detection of HAV. The primers were used in a heminested reverse transcriptase PCR (hnRT-PCR) protocol that was rapid and sensitive for detecting NVG1, NVGII and HAV virus in food. The hnRT-PCR was applied successfully to strawberries and spinach obtained from a local fresh-food market, where we could see NVGI, NVGII and HAV. Keywords: Norovirus1; Hepatitis A2; gastroenteritis3; genotypes4; NVG15; NVGII6; hnRT-PCR7.

Excess acute diarrhoea cases attributed to norovirus variants in Beijing, China between 2011 and 2018.

New norovirus (NoV) variants emerge often leading to increased acute gastroenteritis outbreaks and outpatient visits. However, these increases are rarely quantified. Between September 2011 and August 2018, we included a total of 133 131 acute diarrhoea cases in 11 enteric disease outpatient clinics which were open all year round in Beijing. Over the same period, the etiology surveillance for acute diarrhoea was conducted, a total of 13 139 specimens were collected and tested, and 16.84% (2213/13 139) of all specimens were NoV-positive. The partial VP1 genes were successfully sequenced in 965 NoV strains. GII.4 Sydney, GII.17, and GII.2 predominated in 2012-2013, 2014-2015, and 2016-2017, respectively. We estimated the excess NoV-associated acute diarrhoea cases using the adjusted Serfling regression model, and three excess periods were found, corresponding to the predominance periods of GII.4 Sydney, GII.17 and GII.2, respectively, represented increases of 180.5% (95% confidence interval [CI]: 115.0%-246.0%), 114.7% (95% CI: 66.4%-163.1%) and 152.6% (95% CI: 100.2%-205.0%), compared with the baseline level. New NoV variants often caused an excess in their first year of predominance, and the excess periods of NoV-associated acute diarrhoea cases coincided with the predominance periods of NoV variants.

Genetic Diversity of Norovirus in Children with Acute Gastroenteritis in Southwest Nigeria, 2015–2017

Norovirus (NoV) is a leading cause of viral gastroenteritis globally, especially in children below five years. Epidemiological studies on the diversity of NoV in middle- and low-income countries, including Nigeria, are limited. This study aimed to determine the genetic diversity of NoV in children below five years with acute gastroenteritis at three hospitals in Ogun State, Nigeria. A total of 331 fecal samples were collected from February 2015 to April 2017, while 175 were randomly selected and analyzed using RT-PCR, partial sequencing and phylogenetic analyses of both the polymerase (RdRp) and capsid (VP1) genes. NoV was detected in 5.1% (9/175; RdRp) and 2.3% (4/175; VP1) of samples, with 55.6% (5/9) co-infection with other enteric viruses. A diverse genotype distribution was identified, and GII.P4 was the dominant RdRp genotype detected (66.7%), with two genetic clusters, followed by GII.P31 (22.2%). The rare GII.P30 genotype (11.1%) was detected at a low rate for the first time in Nigeria. Based on the VP1 gene, GII.4 was the dominant genotype (75%), with two variants, Sydney 2012 and possibly New Orleans 2009, co-circulating during the study. Interestingly, both intergenotypic, GII.12(P4) and GII.4 New Orleans(P31), and intra-genotypic, GII.4 Sydney(P4) and GII.4 New Orleans(P4), putative recombinant strains were observed. This finding suggests the first likely report of GII.4 New Orleans(P31) in Nigeria. In addition, GII.12(P4) was first described in Africa and globally in this study, to the best of our knowledge. This study provided insights into the genetic diversity of NoV circulating in Nigeria, which would be useful for ongoing and future vaccine design and monitoring of emerging genotypes and recombinant strains.

Rare Recombinant GI.5[P4] Norovirus That Caused a Large Foodborne Outbreak of Gastroenteritis in a Hotel in Spain in 2021.

Noroviruses are among the most important causes of acute gastroenteritis (AGE). In summer 2021, a large outbreak of norovirus infections affecting 163 patients, including 15 norovirus-confirmed food handlers, occurred in a hotel in Murcia in southeast Spain. A rare GI.5[P4] norovirus strain was identified as the cause of the outbreak. The epidemiological investigation determined that norovirus transmission might have been initiated through an infected food handler. The food safety inspection found that some symptomatic food handlers continued working during illness. Molecular investigation with whole-genome and ORF1 sequencing provided enhanced genetic discrimination over ORF2 sequencing alone and enabled differentiation of the GI.5[P4] strains into separate subclusters, suggesting different chains of transmission. These recombinant viruses have been identified circulating globally over the last 5 years, warranting further global surveillance. IMPORTANCE Due to the large genetic diversity of noroviruses, it is important to enhance the discriminatory power of typing techniques to differentiate strains when investigating outbreaks and elucidating transmission chains. This study highlights the importance of (i) using whole-genome sequencing to ensure genetic differentiation of GI noroviruses to track chains of transmission during outbreak investigations and (ii) the adherence of symptomatic food handlers to work exclusion rules and strict hand hygiene practices. To our knowledge, this study provides the first full-length genome sequences of GI.5[P4] strains apart from the prototype strain.

Molecular epidemiology and evolution of human noroviruses

Noroviruses are the most common viral cause of acute gastroenteritis after the introduction of rotavirus vaccines. Norovirus infection can cause severe symptoms in vulnerable populations including young children and the elderly. Thus, it is still a leading cause of death from diarrhea in children in developing countries. Recent advancement of genomics platforms facilitated understanding of the epidemiology of norovirus, while the whole picture of norovirus diversity is still undetermined. Currently, there are no approved vaccines for norovirus, but state-of-the-art norovirus cultivation systems could elucidate the antigenic diversity of this fast-evolving virus. In this review, we will summarize the historical and latest findings of norovirus epidemiology, diversity, and evolution.

Multiple Novel Human Norovirus Recombinants Identified in Wastewater in Pretoria, South Africa by Next-Generation Sequencing.

The genogroup II genotype 4 (GII.4) noroviruses are a major cause of viral gastroenteritis. Since the emergence of the Sydney_2012 variant, no novel norovirus GII.4 variants have been reported. The high diversity of noroviruses and periodic emergence of novel strains necessitates continuous global surveillance. The aim of this study was to assess the diversity of noroviruses in selected wastewater samples from Pretoria, South Africa (SA) using amplicon-based next-generation sequencing (NGS). Between June 2018 and August 2020, 200 raw sewage and final effluent samples were collected fortnightly from two wastewater treatment plants in Pretoria. Viruses were recovered using skimmed milk flocculation and glass wool adsorption-elution virus recovery methods and screened for noroviruses using a one-step real-time reverse-transcription PCR (RT-PCR). The norovirus BC genotyping region (570-579 bp) was amplified from detected norovirus strains and subjected to Illumina MiSeq NGS. Noroviruses were detected in 81% (162/200) of samples. The majority (89%, 89/100) of raw sewage samples were positive for at least one norovirus, compared with 73% (73/100) of final effluent samples. Overall, a total of 89 different GI and GII RdRp-capsid combinations were identified, including 51 putative novel recombinants, 34 previously reported RdRp-capsid combinations, one emerging novel recombinant and three Sanger-sequencing confirmed novel recombinants.

The emergence of recombinant norovirus GII.12[P16] and predominance of GII.3[P12] strains in pediatric patients with acute gastroenteritis in Thailand, 2019-2020.

Norovirus (NoV) and sapovirus (SaV) are important pathogens that cause acute gastroenteritis (AGE) in all age groups, commonly in children worldwide. Recently, a number of studies have reported a wide variety of NoV recombinant strains. This study aimed to investigate the distribution of NoV and SaV recombinant strains circulating in Chiang Mai, Thailand, during 2019-2020. One hundred and twenty-four NoV and seven SaV strains detected in children admitted to the hospital with AGE were included in this study. The partialRNA-dependent RNA-polymerase(RdRp)/VP1 regions of these NoV and SaV strains were analyzed by phylogenetic analysis, Simplot, and RDP software. Overall, eight recombination patterns of NoV were detected. NoV GII.4[P16] was the most common strain detected (39.1%), followed by GII.3[P12] (25.0%), GII.4[P31] (17.2%), and other recombinant strains were detected at a lower rate. NoV GII.12[P16] strains were detected for the first time in Thailand. For SaV, none of the recombinant strains was detected. All SaV strains, GI.1/GI.1, GI.2/GI.2, and GII.5/GII.5, exhibited VP1 genotype corresponded to RdRp genotype. In conclusion, this study demonstrates the distribution and diversity of NoV and SaV recombinant strains circulating in pediatric patients with AGE in Chiang Mai, during 2019-2020 with the emergence of NoV GII.3[P12] and GII.12[P16].