Evaluation of real-time RT-PCR assays for detection and quantification of norovirus genogroups I and II

Validation of one-step reverse transcription digital PCR assays for Norovirus GI

Regular monitoring of Norovirus presence in environmental and food samples is crucial due to its high transmission rates and outbreak potential. For detecting Norovirus GI, reverse transcription qPCR method is commonly used, but its sensitivity can be affected by assay performance. This study shows significantly reduced assay performance in digital PCR or qPCR when using primers targeting Norovirus GI genome 5291-5319 (NC_001959), located on the hairpin of the predicted RNA structure. It is highly recommended to avoid this region in commercial kit development or diagnosis to minimizing potential risk of false negatives.

Detection accuracy and clinical applications of DP-TOF mass spectrometry

OBJECTIVE

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is currently used in clinical microbiology laboratories. This study aimed to determine whether dual-polarity time-of-flight mass spectrometry (DP-TOF MS) could be applied to clinical nucleotide detection.

METHODS

This prospective study included 40 healthy individuals and 110 patients diagnosed with cardiovascular diseases. We used DP-TOF MS and Sanger sequencing to evaluate 17 loci across 11 genes associated with cardiovascular drug responses. In addition, we used DP-TOF MS to test 998 retrospectively collected clinical DNA samples with known results.

RESULTS

A, T, and G nucleotide detection by DP-TOF MS and Sanger sequencing revealed 100% concordance, whereas the C nucleotide concordance was 99.86%. Genotyping based on the results of the two methods showed 99.96% concordance. Regarding clinical applications, DP-TOF MS yielded a 99.91% concordance rate for known loci. The minimum detection limit for DNA was 0.4 ng; the inter-assay and intra-assay precision rates were both 100%. Anti-interference analysis showed that aerosol contamination greater than 1013 copies/µL in the laboratory environment could influence the results of DP-TOF MS.

CONCLUSIONS

The DP-TOF MS platform displayed good detection performance, as demonstrated by its 99.96% concordance rate with Sanger sequencing. Thus, it may be applied to clinical nucleotide detection.

Development and Evaluation of a Rapid GII Norovirus Detection Method Based on CRISPR-Cas12a

Norovirus is highly infectious and rapidly transmissible and represents a major pathogen of sporadic cases and outbreaks of acute gastroenteritis worldwide, causing a substantial disease burden. Recent years have witnessed a dramatic increase in norovirus outbreaks in China, significantly higher than in previous years, among which GII norovirus is the predominant prevalent strain. Therefore, rapid norovirus diagnosis is critical for clinical treatment and transmission control. Hence, we developed a molecular assay based on RPA combined with the CRISPER-CAS12a technique targeting the conserved region of the GII norovirus genome, the results of which could be displayed by fluorescence curves and immunochromatographic lateral-flow test strips. The reaction only required approximately 50 min, and the results were visible by the naked eye with a sensitivity reaching 102 copies/μl. Also, our method does not cross-react with other common pathogens that cause intestinal diarrhea. Furthermore, this assay was easy to perform and inexpensive, which could be widely applied for detecting norovirus in settings including medical institutions at all levels, particularly township health centers in low-resource areas.

Spatial Distribution and Enrichment Dynamics of Foodborne Norovirus in Oyster Tissues

The prevalence of norovirus in oysters poses a significant threat to food safety, necessitating a comprehensive understanding of contamination patterns. This study explores the temporal dynamics of norovirus distribution in various oyster tissues over a contamination period ranging from 6 to 96 h. Four tissues-the gill, palp, digestive gland, and stomach-were subjected to systematic monitoring using RT-qPCR for absolute quantification. Results revealed rapid norovirus detection in all tissues six hours post-contamination, with subsequent variations in detection rates. Gill and digestive gland tissues exhibited a peak in detection at 12-24 h, aligning with the oyster's gastrointestinal circulatory system. The digestive gland, distinguished by specific enrichment and adsorption capabilities, demonstrated the highest virus concentration at 48 h. In contrast, the stomach displayed a reemergence of norovirus. Beyond 72 h, detection remained exclusive to the digestive gland, with Ct values comparable to earlier time points. At 96 h, a limited amount of norovirus was detected in the digestive gland, emphasizing the importance for timely monitoring. In addition to providing critical insights into optimal detection strategies, these findings highlight the time-related characteristics of norovirus contamination in oysters. The study identifies the digestive gland as a key target for reliable monitoring, providing valuable data to improve protocols for reducing hazards associated with oyster consumption and foodborne norovirus infections. This research contributes to the understanding of norovirus dynamics in oyster tissues and reinforces current efforts aimed at ensuring food safety and public health.

Human Norovirus Detection: How Much Are We Prepared?

Norovirus (NoV) is known to be the second nonbacterial enteric pathogen after rotavirus that causes acute gastroenteritis. They can be spread from person to person through fecal-oral routes. Infection can lead to severe diarrhea, causing stomach pain, vomiting, and nausea. Rapid detection of NoV can control huge economic and productive losses. Genotyping various emerging NoV strains is important to compare the severity among different strains. Conventional immunological and molecular methods have evolved and contributed to developing detection techniques. Immunological (enzyme-linked immunosorbent assay) and molecular detection (reverse transcriptase polymerase chain reaction [RT-PCR], RT-quantitative PCR, loop-mediated isothermal amplification, nucleic acid sequence-based alignment, recombinase polymerase amplification) methods have been mainly used. The development of biosensors using aptasensor, affinity peptides, nanoparticles, microfluidics, and so on, are currently the most researched topics. The availability of next-generation sequencing technologies has greatly influenced the diagnosis of NoV. The complementation of advanced technologies is helpful in identification of new variants. In this study, techniques that are useful in detecting NoV are discussed. This review has investigated the availability of recent methods used in the detection, present status, and futuristic plan of action in case of outbreak and pandemic.

Performance evaluation of QuantStudio 1 plus real-time PCR instrument for clinical laboratory analysis: A proof-of-concept study

Objective

The real-time PCR system is one of the most powerful research tools available in the life sciences field. The aim of this study was to preliminarily evaluate the analytical performance of QuantStudio 1 Plus real-time PCR system (QS 1 plus) for clinical procedures.

Methods

The consistency of QS 1 plus with the reference system in terms of various clinical procedures was evaluated. For qualitative data, the Kappa test was used to analyze the agreement of the results. For the quantitative data, Passing-Bablok regression analysis and Bland-Altman plot analysis were used to assess the concordance between QS 1 plus and the reference instrument.

Results

Passing-Bablok regression showed an excellent agreement between the QS 1 plus and LC 480 systems for HBV DNA quantification (y = 0.928 + 0.970x), whereas Bland-Altman plot analysis showed very small mean deviations between the two systems. The QS 1 plus yielded perfectly consistent results with the reference instrument for methylenetetrahydrofolate reductase (MTHFR) C677T melting curve genotyping analysis, MTHFR C677T genotyping analysis, Norovirus RNA negative/positive analysis, influenza B virus (Flu B) RNA negative/positive analysis, Mycobacterium tuberculosis (MTB) DNA negative/positive analysis, Human Papillomavirus (HPV) genotyping analysis, epidermal growth factor receptor (EGFR) gene mutation analysis. Both the relative quantitative analysis and the relative quantitative analysis (standard curve) confirmed the satisfactory concordance between the QS 1 plus instrument and the ABI 7500 instrument by Passing-Bablok regression analysis (y = 0.180 + 0.817x and y = 0.012 + 1.000x, respectively) and Bland-Altman plot analysis.

Conclusions

Our research has proven that QS 1 plus is adaptable to most test procedures in the clinical laboratory. This may provide the basis for its further application.

Efficient SARS-CoV-2 Surveillance during the Pandemic-Endemic Transition Using PCR-Based Genotyping Assays

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants of concern (VOC) pose an increased risk to public health due to higher transmissibility and/or immune escape. In this study, we assessed the performance of a custom TaqMan SARS-CoV-2 mutation panel consisting of 10 selected real-time PCR (RT-PCR) genotyping assays compared to whole-genome sequencing (WGS) for identification of 5 VOC circulating in The Netherlands. SARS-CoV-2 positive samples (N = 664), collected during routine PCR screening (15 ≤ CT ≤ 32) between May-July 2021 and December 2021-January 2022, were selected and analyzed using the RT-PCR genotyping assays. VOC lineage was determined based on the detected mutation profile. In parallel, all samples underwent WGS with the Ion AmpliSeq SARS-CoV-2 research panel. Among 664 SARS-CoV-2 positive samples, the RT-PCR genotyping assays classified 31.2% as Alpha (N = 207); 48.9% as Delta (N = 325); 19.4% as Omicron (N = 129), 0.3% as Beta (N = 2), and 1 sample as a non-VOC. Matching results were obtained using WGS in 100% of the samples. RT-PCR genotyping assays enable accurate detection of SARS-CoV-2 VOC. Furthermore, they are easily implementable, and the costs and turnaround time are significantly reduced compared to WGS. For this reason, a higher proportion of SARS-CoV-2 positive cases in the VOC surveillance testing can be included, while reserving valuable WGS resources for identification of new variants. Therefore, RT-PCR genotyping assays would be a powerful method to include in SARS-CoV-2 surveillance testing. IMPORTANCE The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) genome changes constantly. It is estimated that there are thousands of variants of SARS-CoV-2 by now. Some of those variants, variants of concern (VOC), pose an increased risk to public health due to higher transmissibility and/or immune escape. Pathogen surveillance helps researchers, epidemiologists, and public health officials to monitor the evolution of infectious diseases agents, alert on the spread of pathogens, and develop counter measures like vaccines. The technique used for the pathogen surveillance is called sequence analysis which makes it possible to examine the building blocks of SARS-CoV-2. In this study, a new PCR method based on the detection of specific changes of those building blocks is presented. This method enables a fast, accurate and cheap determination of different SARS-CoV-2 VOC. Therefore, it would be a powerful method to include in SARS-CoV-2 surveillance testing.

SGAEMDA: Predicting miRNA-Disease Associations Based on Stacked Graph Autoencoder

MicroRNA (miRNA)-disease association (MDA) prediction is critical for disease prevention, diagnosis, and treatment. Traditional MDA wet experiments, on the other hand, are inefficient and costly.Therefore, we proposed a multi-layer collaborative unsupervised training base model called SGAEMDA (Stacked Graph Autoencoder-Based Prediction of Potential miRNA-Disease Associations). First, from the original miRNA and disease data, we defined two types of initial features: similarity features and association features. Second, stacked graph autoencoder is then used to learn unsupervised low-dimensional representations of meaningful higher-order similarity features, and we concatenate the association features with the learned low-dimensional representations to obtain the final miRNA-disease pair features. Finally, we used a multilayer perceptron (MLP) to predict scores for unknown miRNA-disease associations. SGAEMDA achieved a mean area under the ROC curve of 0.9585 and 0.9516 in 5-fold and 10-fold cross-validation, which is significantly higher than the other baseline methods. Furthermore, case studies have shown that SGAEMDA can accurately predict candidate miRNAs for brain, breast, colon, and kidney neoplasms.

Ultrasensitive and visual detection of human norovirus genotype GII.4 or GII.17 using CRISPR-Cas12a assay

Background

Integrating CRISPR-Cas12a sensors with isothermal signal amplification can be exploited to develop low-cost, disposable, and ultrasensitive assays for the diagnostics of human pathogens.

Methods

RT-RAA-Cas12a-mediated real-time or end-point fluorescent and lateral flow strip (LFS) assays for direct detection of norovirus (NOV) genotype GII.4 or GII.17 were explored.

Results

The results showed that our RT-RAA-Cas12a-mediated fluorescent and LFS assay could detect NOV GII.4 or GII.17 by targeting the viral protein 1 gene. Our RT-RAA-Cas12a-mediated fluorescent and LFS assay can specifically detect NOV GII.4 or GII.17 with no cross-reactivity for other related viruses. The low limit of detection could reach 0.1 copies/μL within approximately 30–40 min, and the results were visualized using an ultraviolet light illuminator or on a LFS without complex equipment. In addition, our RT-RAA-Cas12a-mediated fluorescent and LFS assay provided a visual and faster alternative to real-time RT-PCR assay, with 95.7% and 94.3% positive predictive agreement and 100% negative predictive agreement.

Conclusions

Together, our RT-RAA-Cas12a-mediated approach would have a great potential for point-of-care diagnostics of NOV GII.4 and/or GII.17 in resource-limited settings.

MicroRNA-203a-3p may prevent the development of thyroid papillary carcinoma via repressing MAP3K1 and activating autophagy

Background

Papillary thyroid carcinoma (PTC) grows slowly but has a great risk of metastasis. MicroRNAs are well known as vital tumor‐related gene regulators. In PTC, the role of miR‐203a‐3p and the underlying mechanisms remain not completely understood.

Methods

We conducted CCK8 assay, wound healing assay, transwell experiment and flow cytometry analyses to investigate the function of miRNA‐203a‐3p. The interaction of miRNA‐203a‐3p with its gene MAP3K1 was characterized by quantitative real‐time polymerase chain reaction, western blotting and luciferase assay.

Results

We found that the levels of miRNA‐203a‐3p were statistically decreased in PTC tissues. When mimics were delivered to TPC‐1 and KTC‐1 cells to upregulate miR‐203a‐3p, it was observed that cell proliferation, metastatic abilities and cell cycle process were prevented but cell apoptosis was enhanced. Furthermore, we proved the interaction between MAP3K1 and miR‐203a‐3p. Intriguingly, similar to miR‐203a‐3p mimics, siMAP3K1 showed a tumor‐suppressive effect, and this effect could be reversed when miR‐203a‐3p was simultaneously inhibited. Finally, selected autophagy‐linked proteins such as LC3 Beclin‐1 were detected and found to be increased when miR‐203a‐3p was upregulated or MAP3K1 was inhibited.

Conclusion

Overall, miR‐203a‐3p inhibits the oncogenic characteristics of TPC‐1 and KTC‐1 cells via suppressing MAP3K1 and activating autophagy. Our findings might enrich the understanding and the therapeutic strategies of PTC.

Clinical significance and intestinal microbiota composition in immunocompromised children with norovirus gastroenteritis

Background

Norovirus (NoV) infection is common in pediatric patients with immunodeficiency and is more likely to cause severe disease. Objective Our study aims to figure out the clinical differences and distribution of intestinal microbiota in immunocompromised children with NoV gastroenteritis.

Methods

Pediatric patients admitted to Shang-Ho Hospital with diagnosis of acute gastroenteritis including different immune status were enrolled and their medical records were reviewed. NoV gastroenteritis was validated using RT-PCR molecular methods. Viral shedding period was determined by real-time RT-PCR assays. Intestinal microbiota enrichment analysis was carried out by next generation sequencing after fecal DNA extraction and subsequent Linear Discriminant Analysis (LDA) Effect Size (LEfSe) method.

Results

Significantly higher frequency of diarrhea [mean, (IQR), 3.8 (3–5) /day] and longer viral shedding time [mean, IQR, 8.5 (5–13) days] was found in immunocompromised NoV infections than in immunocompetent patients without NoV infections (p = 0.013*) and immunocompetent patients with NoV infections (p = 0.030**). The fever prevalence was significantly lower in immunocompromised NoV infections than in different immune or infection status. Intestinal microbiota metagenomics analysis showed no significant community richness difference while the LEfSe analysis showed a significant difference in commensal richness at the phylum level, the family level, and the genus level in patients under different immune status.

Conclusion

We evaluated the clinical significances and microbiota composition in immunocompromised children with norovirus gastroenteritis. This will further facilitate studies of the interaction between the intestinal microbiota in such patients with precise determination of their bacterial infection control and probiotic supplements strategy.

Multiplex PCR method for the detection of human norovirus, Salmonella spp., Shigella spp., and shiga toxin producing Escherichia coli in blackberry, coriander, lettuce and strawberry

A multiplex PCR method was developed for the simultaneous detection of murine norovirus (MNV-1) as a surrogate for human norovirus (HuNoV) GI and GII, Salmonella spp., Shigella spp., and Shiga toxin producing Escherichia coli (STEC) in fresh produce. The toxicity of the glycine buffer on bacterial pathogens viability was evaluated. The growth of each of the three pathogens (previously stressed) was evaluated at 35 and 41.5 °C in modified buffered peptone water (mBPW) and trypticase soy broth (TSB), supplemented with vancomycin, novobiocin and brilliant green at two concentration levels. The selected conditions for simultaneous enrichment were: 41.5 °C/mBPW/supplemented with 8 ppm vancomycin, 0.6 ppm novobiocin and 0.2 ppm brilliant green. The pathogens and aerobic plate count (APC) growth was evaluated in the enrichment of lettuce, coriander, strawberry and blackberry under the best enrichment conditions. Starting from 1 to 10 CFU/mL, Salmonella reached from 7.63 to 8.91, Shigella 6.81 to 7.76 and STEC 7.43 to 9.27 log CFU/mL. The population reached for the APC was 5.11-6.56 log CFU/mL. Simultaneous detection by PCR was done using designed primers targeting invA, ipaH, stx1 and stx2 genes, and MNV-1. The detection sensitivity was 10-100 PFU for the MNV-1 and 1-10 CFU for each pathogenic bacteria. This protocol takes 6 h for MNV-1 and 24 h for Salmonella spp., Shigella spp., and STEC detection from the same food portion. In total, 200 samples were analyzed from retail markets from Queretaro, Mexico. Two strawberry samples were positive for HuNoV GI and one lettuce sample was positive for STEC. In conclusion, the method developed in this study is capable of detecting HuNoV GI and GII, Salmonella spp., Shigella spp and STEC from the same fresh produce sample.

Diagnostic Accuracy of Immunochromatographic Tests for the Detection of Norovirus in Stool Specimens: a Systematic Review and Meta-Analysis

Noroviruses are the leading cause of acute gastroenteritis in all age groups and constitute a major health and economic burden worldwide. This systematic review and meta-analysis aimed to determine the diagnostic accuracy of immunochromatographic tests (ICTs) for the detection of norovirus in stool specimens, which has not been performed previously. In this systematic review and meta-analysis (registered on PROSPERO, CRD42020186911), we searched Medline/PubMed, Embase, Cochrane Library, and Web of Science for all studies published up to 16 May 2020. The values for sensitivity, specificity, positive likelihood ratio (LR+), negative likelihood ratio (LR-), and diagnostic odds ratio (DOR) of ICTs with 95% confidence interval (CI) were pooled using a bivariate random-effects model. The summary receiver operating characteristic curve and area under the curve were used to summarize overall test accuracy. We included 43 studies describing 7,428 samples. The overall estimates of sensitivity, specificity, LR+, LR-, DOR, and accuracy of ICT for diagnosing norovirus were 0.61 (95% CI, 0.54 to 0.67), 0.97 (95% CI, 0.95 to 0.98), 17.08 (95% CI, 11.15 to 26.18), 0.40 (95% CI, 0.34 to 0.46), 53.9 (95% CI, 31.32 to 92.78), and 0.928, respectively. Significant differences in pooled sensitivities were noted between age groups and in pooled DOR and LR+ between genogroups of included samples. ICT provides low sensitivity but high specificity and accuracy for detecting norovirus. Thus, an ICT for norovirus can be a rapid and convenient way for identifying patients early; however, a negative result cannot rule out norovirus infection and should be confirmed by a reference test.

Viral shedding in gastroenteritis in children caused by variants and novel recombinant norovirus infections

Human norovirus (NoV) is the leading cause of acute gastroenteritis and the rapid transmission of NoV renders infection control problematic. Our study aimed to investigate viral shedding in gastroenteritis in children caused by variants of emerging norovirus strains infections.We used RNA-dependent RNA polymerase (RdRp) sequencing to measure NoV genome copies in stool to understand the relationship between the clinical manifestations and viral shedding in hospitalized patients. The near full-length NoV genome sequence was amplified via reverse transcription-polymerase chain reaction (RT-PCR) and NoV recombination was analyzed using the Recombination Analysis Tool (RAT).From January 2015 to March 2018, 77 fecal specimens were collected from hospitalized pediatric patients with confirmed NoV gastroenteritis. The NoV genotypes were GII.4 (n = 22), non-GII.4 (n = 14), GII.4 Sydney (n = 21), and GII.P16-GII.2 (n = 20). Viral load increased from days 2 to 9 from the illness onset, resulting in an irregular plateau without peaks. After day 9, the viral load declined gradually and most viral shedding in feces ceased by day 15. The average viral load was highest in GII.4 Sydney followed by GII.P16-GII.2 infections and lowest in non-GII.4 infections. GII.4 unclassified infections showed the longest viral shedding time, followed by GII.4 Sydney infections, GII.P16-GII.2 recombinant infection resulted in the shortest duration. NoVs evolved to form a group of GII.P16-GII.2 variants during the 2017 to 2018 period.The viral load and shedding period and was different in variants of NoV infections in children. High mutation rate of emerging and re-emerging variants was observed to an enhanced epidemic risk rendering continuous surveillance.

Development of a reverse transcription (RT) polymerase chain reaction (PCR) method for the detection of human norovirus in bivalve molluscs

Noroviruses are significant seafood-borne pathogens, commonly associated with the consumption of filter feeding bivalve molluscs. Here, we report the development of a reverse transcription polymerase chain reaction (RT-PCR) method using primers based on the RNA-dependent RNA polymerase gene of norovirus genogroup II (NoV GII). Samples of bivalves were processed for the concentration of virus and extraction of RNA, followed by reverse transcription PCR. A total of 50 molluscan shellfish samples were analyzed, of which 16 samples yielded positive amplifications of norovirus nucleic acid. The PCR method described here, involving a single set of primers, is useful for rapid screening of shellfish for NoV GII.

Prediction of Potential miRNA-Disease Associations Through a Novel Unsupervised Deep Learning Framework with Variational Autoencoder

The important role of microRNAs (miRNAs) in the formation, development, diagnosis, and treatment of diseases has attracted much attention among researchers recently. In this study, we present an unsupervised deep learning model of the variational autoencoder for MiRNA–disease association prediction (VAEMDA). Through combining the integrated miRNA similarity and the integrated disease similarity with known miRNA–disease associations, respectively, we constructed two spliced matrices. These matrices were applied to train the variational autoencoder (VAE), respectively. The final predicted association scores between miRNAs and diseases were obtained by integrating the scores from the two trained VAE models. Unlike previous models, VAEMDA can avoid noise introduced by the random selection of negative samples and reveal associations between miRNAs and diseases from the perspective of data distribution. Compared with previous methods, VAEMDA obtained higher area under the receiver operating characteristics curves (AUCs) of 0.9118, 0.8652, and 0.9091 ± 0.0065 in global leave-one-out cross validation (LOOCV), local LOOCV, and five-fold cross validation, respectively. Further, the AUCs of VAEMDA were 0.8250 and 0.8237 in global leave-one-disease-out cross validation (LODOCV), and local LODOCV, respectively. In three different types of case studies on three important diseases, the results showed that most of the top 50 potentially associated miRNAs were verified by databases and the literature.

Age, primary symptoms, and genotype characteristics of norovirus outbreaks in Shanghai schools in 2017

Sixty norovirus outbreaks that occurred in Pudong District, Shanghai in 2017 and affected 959 people were summarised. Of the outbreaks, 29 (48.3%), 27 (45.0%), and 4 (6.7%) occurred in kindergartens, primary schools, and middle schools, respectively. Although the total number of outbreaks peaked in March (13/60, 21.7%), outbreaks in kindergartens and primary schools peaked in April (6/29, 20.7%) and March (8/27, 29.6%), respectively. Primary schools had the highest median number of cases per outbreak (19) and the highest proportion of cases (54.6%). The male-to-female case ratio differed among school classifications, with the highest male case ratio (69.2%) occurring in middle schools. Primary symptoms also differed across the school classifications. Molecular virology analysis showed that a single viral strain caused each outbreak at each school. In turn, 50.6, 28.8, and 20.6% of cases were infected by GII.4, GII.2, and GII.17, respectively. Vomiting was seen in 98.2, 97.3, and 88.6% of the subjects infected with noroviruses GII.17, GII.4, and GII.2, respectively, and nausea in 73.6, 43.9, and 39.0%. In conclusion, noroviruses mainly affect primary school and kindergarten students. GII.4, GII.2, and GII.17 are the main epidemic strains in the local area, and the primary symptoms differed by age and genotype.

Genetic Diversity Among Genogroup II Noroviruses and Progressive Emergence of GII.17 in Wastewaters in Italy (2011-2016) Revealed by Next-Generation and Sanger Sequencing

Noroviruses (NoV) are a major cause of gastroenteritis worldwide. Recently, a novel variant of NoV GII.17 (GII.P17_GII.17 NoV), termed Kawasaki 2014, has been increasingly reported in NoV outbreaks in Asia, and has also been described in Europe and North America. In this study, sewage samples were investigated to study the occurrence and genetic diversity of NoV genogroup II (GII) along a 6-year period. Moreover, the spread of GII.17 strains (first appearance and occurrence along time) was specifically assessed. A total of 122 sewage samples collected from 2011 to 2016 from four wastewater treatment plants in Rome (Italy) were initially tested using real-time RT-(q)PCR for GII NoV. Positive samples were subsequently subjected to genotypic characterization by RT-nested PCRs using broad-range primes targeting the region C of the capsid gene of GII NoV, and specific primers targeting the same region of GII.17 NoV. In total, eight different genotypes were detected with the broad-range assay: GII.1 (n = 6), GII.2 (n = 8), GII.3 (n = 3), GII.4 (n = 13), GII.6 (n = 3), GII.7 (n = 2), GII.13 (n = 2), and GII.17 (n = 3), with the latter two genotypes detected only in 2016. Specific amplification of GII.17 NoV was successful in 14 out of 110 positive samples, spanned over the years 2013-2016. The amplicons of the broad-range PCR, pooled per year, were further analyzed by next-generation sequencing (NGS) for a deeper analysis of the genotypes circulating in the study period. NGS confirmed the circulation of GII.17 NoV since 2013 and detected, beyond the eight genotypes identified by Sanger sequencing, three additional genotypes regarded as globally uncommon: GII.5, GII.16, and GII.21. This study provides evidence that GII.17 NoV Kawasaki has been circulating in the Italian population before its appearance and identification in clinical cases, and has become a major genotype in 2016. Our results confirm the usefulness of wastewater surveillance coupled with NGS to study the molecular epidemiology of NoV and to monitor the emergence of NoV strains.