Genomic Epidemiology of SARS-CoV-2 in Guangdong Province, China.

Coronavirus disease 2019 (COVID-19) is caused by SARS-CoV-2 infection and was first reported in central China in December 2019. Extensive molecular surveillance in Guangdong, China's most populous province, during early 2020 resulted in 1,388 reported RNA-positive cases from 1.6 million tests. In order to understand the molecular epidemiology and genetic diversity of SARS-CoV-2 in China, we generated 53 genomes from infected individuals in Guangdong using a combination of metagenomic sequencing and tiling amplicon approaches. Combined epidemiological and phylogenetic analyses indicate multiple independent introductions to Guangdong, although phylogenetic clustering is uncertain because of low virus genetic variation early in the pandemic. Our results illustrate how the timing, size, and duration of putative local transmission chains were constrained by national travel restrictions and by the province's large-scale intensive surveillance and intervention measures. Despite these successes, COVID-19 surveillance in Guangdong is still required, because the number of cases imported from other countries has increased.

Human angiotensin-converting enzyme 2-specific antisense oligonucleotides reduce infection with SARS-CoV-2 variants.

BACKGROUND: The Spike protein mutation severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) led to decreased protective effect of various vaccines and mAbs, suggesting that blocking SARS-CoV-2 infection by targeting host factors would make the therapy more resilient against virus mutations. Angiotensin-converting enzyme 2 (ACE2) is the host receptor of SARS-CoV-2 and its variants, as well as many other coronaviruses. Downregulation of ACE2 expression in the respiratory tract may prevent viral infection. Antisense oligonucleotides (ASOs) can be rationally designed on the basis of sequence data, require no delivery system, and can be administered locally. OBJECTIVE: We sought to design ASOs that can block SARS-CoV-2 by downregulating ACE2 in human airway. METHODS: ACE2-targeting ASOs were designed using a bioinformatic method and screened in cell lines. Human primary nasal epithelial cells cultured at the air-liquid interface and humanized ACE2 mice were used to detect the ACE2 reduction levels and the safety of ASOs. ASO-pretreated nasal epithelial cells and mice were infected and then used to detect the viral infection levels. RESULTS: ASOs reduced ACE2 expression on mRNA and protein level in cell lines and in human nasal epithelial cells. Furthermore, they efficiently suppressed virus replication of 3 different SARS-CoV-2 variants in human nasal epithelial cells. In vivo, ASOs also downregulated human ACE2 in humanized ACE2 mice and thereby reduced viral load, histopathologic changes in lungs, and increased survival of mice. CONCLUSIONS: ACE2-targeting ASOs can effectively block SARS-CoV-2 infection. Our study provides a new approach for blocking SARS-CoV-2 and other ACE2-targeting virus in high-risk populations.

Transmission Pattern of Measles Virus Circulating in China During 1993-2021: Genotyping Evidence Supports That China Is Approaching Measles Elimination.

BACKGROUND: To provide useful insights into measles elimination progress in China, measles surveillance data were reviewed, and the transmission patterns of measles viruses circulating in China during 1993-2021 were analyzed. METHODS: Measles incidence data from the National Notifiable Disease Reporting System of the China Center for Disease Control and Prevention were analyzed. A total of 17 570 strains were obtained from 30 of 31 provinces in mainland China during 1993-2021. The recommended genotyping window was amplified. Genotyping analysis was conducted for comparison with the reference strains. Phylogenetic analyses were performed to identify genetic relationships among different lineages within the genotypes. RESULTS: With high coverage of routine immunization and intensive supplementary immunization activities, measles incidence has shown a downward trend since 1993, despite 2 resurgences, reaching a historic low level in 2020-2021 (average 0.5 per million). During 1993-2021, 9 genotypes including domestic genotype H1; imported genotypes B3, D4, D8, D9, D11, G3, and H2; and vaccine-associated genotype A were identified. Among them, the genotype H1 strain circulated endemically in China for more than 25 years; the last strain was detected in Yunnan Province in September 2019. Multiple imported genotypes have been identified since 2009 showing different transmission patterns. Since April 2020, no imported strains have been detected, while vaccine-associated genotype A continues to be detected. CONCLUSIONS: The evidence of low incidence during 2020-2021 and virological surveillance data in this study confirm that China is currently approaching measles elimination.

Dynamic changes in polioviruses identified by environmental surveillance in Guangzhou, 2009-2021.

Polio cases can be missed by acute flaccid paralysis (AFP) case surveillance alone, emphasizing the importance of environmental surveillance (ES). In this study, to investigate the serotype distribution and epidemiological trends of poliovirus (PV), we characterized PV isolated from domestic sewage in Guangzhou City, Guangdong Province, China from 2009 to 2021. A total of 624 sewage samples were collected from the Liede Sewage Treatment Plant, and the positive rates of PV and non-polio enteroviruses were 66.67% (416/624) and 78.37% (489/624), respectively. After sewage sample treatment, each sewage sample was inoculated in six replicate tubes of three cell lines, and 3370 viruses were isolated during the 13-year surveillance period. Among these, 1086 isolates were identified as PV, including type 1 PV (21.36%), type 2 PV (29.19%), and type 3 PV (49.48%). Based on VP1 sequences, 1057 strains were identified as Sabin-like, 21 strains were high-mutant vaccines, and eight strains were vaccine-derived poliovirus (VDPV). The numbers and serotypes of PV isolates in sewage were influenced by the vaccine switch strategy. After type 2 OPV was removed from the trivalent oral PV (OPV) vaccine and a bivalent OPV (bOPV) was adopted in May 2016, the last type 2 PV strain was isolated from sewage, with no detection thereafter. Type 3 PV isolates increased significantly and became the dominant serotype. Before and after the second vaccine switch in January 2020, that is, from the first dose of IPV and second-fourth doses of bOPV to the first two doses of IPV and third-fourth doses of bOPV, there was also a statistical difference in PV positivity rates in sewage samples. Seven type 2 VDPVs and one type 3 VDPV were identified in sewage samples in 2009-2021, and phylogenetic analysis indicated that all VDPVs isolated from ES in Guangdong are newly discovered VDPVs, different from VDPV previously discovered in China, and were classified as ambiguous VDPV. It is noteworthy that no VDPV cases were reported in AFP case surveillance in the same period. In conclusion, continued PV ES in Guangzhou since April 2008 has been a useful supplement to AFP case surveillance, providing an important basis for evaluating the effectiveness of vaccine immunization strategies. ES improves early detection, prevention, and control; accordingly, this strategy can curb the circulation of VDPVs and provide a strong laboratory basis for maintaining a polio-free status.

Development and multi-center clinical trials of an up-converting phosphor technology-based point-of-care (UPT-POCT) assay for rapid COVID-19 diagnosis and prediction of protective effects.

BACKGROUND: Quantitative point-of-care testing assay for detecting antibodies is critical to COVID-19 control. In this study, we established an up-conversion phosphor technology-based point-of-care testing (UPT-POCT), a lateral flow assay, for rapid COVID-19 diagnosis, as well as prediction of seral neutralizing antibody (NAb) activity and protective effects. METHODS: UPT-POCT was developed targeting total antibodies against the receptor-binding domain (RBD) of SARS-CoV-2 spike protein. Using ELISA as a contrast method, we evaluated the quantitation accuracy with NAb and serum samples. Cutoff for serum samples was determined through 70 healthy and 140 COVID-19 patients. We evaluated the cross-reactions with antibodies against other viruses. Then, we performed multi-center clinical trials of UPT-POCT, including 782 patients with 387 clinically confirmed COVID-19 cases. Furthermore, RBD-specific antibody levels were detected using UPT-POCT and microneutralization assay for samples from both patients and vaccinees. Specifically, the antibodies of recovered patients with recurrent positive (RP) reverse transcriptase-polymerase chain reaction test results were discussed. RESULTS: The ratios of signal intensities between the test and control bands on the lateral flow strip, namely, T/C ratios, was defined as the results of UPT-POCT. T/C ratios had excellent correlations with concentrations of NAb, as well as OD values of ELISA for serum samples. The sensitivity and specificity of UPT-POCT were 89.15% and 99.75% for 782 cases in seven hospitals in China, respectively. We evaluated RBD-specific antibodies for 528 seral samples from 213 recovered and 99 RP COVID-19 patients, along with 35 seral samples from inactivated SARS-CoV-2 vaccinees, and we discovered that the total RBD-specific antibody level indicated by T/C ratios of UPT-POCT was significantly related to the NAb titers in both COVID-19 patients (r = 0.9404, n = 527; ρ = 0.6836, n = 528) and the vaccinees (r = 0.9063, ρ = 0.7642, n = 35), and it was highly relevant to the protection rate against RP (r = 0.9886, n = 312). CONCLUSION: This study reveals that the UPT-POCT for quantitative detection of total RBD-specific antibody could be employed as a surrogate method for rapid COVID-19 diagnosis and prediction of protective effects.

Comparison of model-specific histopathology in mouse models of COVID-19.

A novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been identified as the causative agent of the current coronavirus disease 2019 pandemic. Development of animal models that parallel the clinical and pathologic features of disease are highly essential to understanding the pathogenesis of SARS-CoV-2 infection and the development of therapeutics and prophylactics. Several mouse models that express the human angiotensin converting enzyme 2 (hACE2) have been created, including transgenic and knock-in strains, and viral vector-mediated delivery of hACE2. However, the comparative pathology of these mouse models infected with SARS-CoV-2 are unknown. Here, we perform systematic comparisons of the mouse models including K18-hACE2 mice, KI-hACE2 mice, Ad5-hACE2 mice and CAG-hACE2 mice, which revealed differences in the distribution of lesions and the characteristics of pneumonia induced. Based on these observations, the hACE2 mouse models meet different needs of SARS-CoV-2 researches. The similarities or differences among the model-specific pathologies may help in better understanding the pathogenic process of SARS-CoV-2 infection and aiding in the development of effective medications and prophylactic treatments for SARS-CoV-2.

Identification of a neutralizing linear epitope within the VP1 protein of coxsackievirus A10.

BACKGROUND: Coxsackievirus A10 (CV-A10) is a leading cause of hand, foot, and mouth disease (HFMD). It is necessary to identify neutralizing epitopes to investigate and develop an epitope-based vaccine against CV-A10. The viral protein VP1 is the immunodominant capsid protein and contains the critical neutralizing epitope. However, neutralizing epitopes within VP1 protein of CV-A10 have not been well characterized. METHODS: Bioinformatics techniques were applied to predict linear epitopes on the CV-A10 VP1 protein. The advanced structural features of epitopes were analyzed by three-dimensional (3D) modeling. The anticipated epitope peptides were synthesized and used to immunize mice as antigens. ELISA and micro-neutralization assay were used to determine the specific IgG antibody and neutralizing antibody titers. The protective efficacy of the epitope peptides in vivo was evaluated using a passive immunization/challenge assay. RESULTS: Three linear epitopes (EP3, EP4, and EP5) were predicted on CV-A10 VP1, all spatially exposed on the capsid surface, and exhibited adequate immunogenicity. However, only EP4, corresponding to residues 162-176 of VP1, demonstrated potent neutralization against CV-A10. To determine the neutralizing capacity of EP4 further, EP4 double-peptide was synthesized and injected into mice. The mean neutralizing antibody titer of the anti-EP4 double-peptide sera was 1:50.79, which provided 40% protection against lethal infection with CV-A10 in neonatal mice. In addition, sequence and advanced structural analysis revealed that EP4 was highly conserved among representative strains of CV-A10 and localized in the EF loop region of VP1, like EV-A71 SP55 or CV-A16 PEP55. CONCLUSIONS: These data demonstrate that EP4 is a specific linear neutralizing epitope on CV-A10 VP1. Its protective efficacy can be enhanced by increasing its copy number, which will be the foundation for developing a CV-A10 epitope-based vaccine.

Ubiquitin-Modified Proteome of SARS-CoV-2-Infected Host Cells Reveals Insights into Virus-Host Interaction and Pathogenesis.

The outbreak of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has posed a serious threat to global public health. The mechanism of pathogenesis and the host immune response to SARS-CoV-2 infection are largely unknown. In the present study, we applied a quantitative proteomic technology to identify and quantify the ubiquitination changes that occur in both the virus and the Vero E6 cells during SARS-CoV-2 infection. By applying label-free, quantitative liquid chromatography with tandem mass spectrometry proteomics, 8943 lysine ubiquitination sites on 3086 proteins were identified, of which 138 sites on 104 proteins were quantified as significantly upregulated, while 828 sites on 447 proteins were downregulated at 72 h post-infection. Bioinformatics analysis suggested that SARS-CoV-2 infection might modulate host immune responses through the ubiquitination of important proteins, including USP5, IQGAP1, TRIM28, and Hsp90. Ubiquitination modification was also observed on 11 SAR-CoV-2 proteins, including proteins involved in virus replication and inhibition of the host innate immune response. Our study provides new insights into the interaction between SARS-CoV-2 and the host as well as potential targets for the prevention and treatment of COVID-19.

Identification of Common Deletions in the Spike Protein of Severe Acute Respiratory Syndrome Coronavirus 2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel coronavirus first identified in December 2019. Notable features that make SARS-CoV-2 distinct from most other previously identified betacoronaviruses include a receptor binding domain and a unique insertion of 12 nucleotides or 4 amino acids (PRRA) at the S1/S2 boundary. In this study, we identified two deletion variants of SARS-CoV-2 that either directly affect the polybasic cleavage site itself (NSPRRAR) or a flanking sequence (QTQTN). These deletions were verified by multiple sequencing methods. In vitro results showed that the deletion of NSPRRAR likely does not affect virus replication in Vero and Vero-E6 cells; however, the deletion of QTQTN may restrict late-phase viral replication. The deletion of QTQTN was detected in 3 of 68 clinical samples and 12 of 24 in vitro-isolated viruses, while the deletion of NSPRRAR was identified in 3 in vitro-isolated viruses. Our data indicate that (i) there may be distinct selection pressures on SARS-CoV-2 replication or infection in vitro and in vivo; (ii) an efficient mechanism for deleting this region from the viral genome may exist, given that the deletion variant is commonly detected after two rounds of cell passage; and (iii) the PRRA insertion, which is unique to SARS-CoV-2, is not fixed during virus replication in vitro These findings provide information to aid further investigation of SARS-CoV-2 infection mechanisms and a better understanding of the NSPRRAR deletion variant observed here.IMPORTANCE The spike protein determines the infectivity and host range of coronaviruses. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has two unique features in its spike protein, the receptor binding domain and an insertion of 12 nucleotides at the S1/S2 boundary resulting in a furin-like cleavage site. Here, we identified two deletion variants of SARS-CoV-2 that either directly affect the furin-like cleavage site itself (NSPRRAR) or a flanking sequence (QTQTN), and we investigated these deletions in cell isolates and clinical samples. The absence of the polybasic cleavage site in SARS-CoV-2 did not affect virus replication in Vero or Vero-E6 cells. Our data indicate the PRRAR sequence and the flanking QTQTN sequence are not fixed in vitro; thus, there appears to be distinct selection pressures on SARS-CoV-2 sequences in vitro and in vivo Further investigation of the mechanism of generating these deletion variants and their infectivity in different animal models would improve our understanding of the origin and evolution of this virus.

Molecular surveillance of coxsackievirus A16 in southern China, 2008-2019.

A national surveillance system on hand, foot, and mouth disease (HFMD) was launched in 2008 in China. Since then, millions of HFMD cases have been reported each year, with enterovirus A71 (EV-A71), coxsackievirus A16 (CV-A16), and coxsackievirus A6 (CV-A6) as the major causative pathogens. Long-term surveillance of viral infection rates and genetic changes is essential for understanding the disease epidemiology pattern. Here, we analyzed molecular surveillance data on CV-A16 covering a period of 12 years (2008-2019) in Guangdong, China, one of the regions reporting the largest number of HFMD cases. Full VP1 sequences of 456 strains were determined to examine the genetic diversity and changes in the distribution of CV-A16 variants. Our study revealed an irregular pattern of CV-A16 infections in Guangdong. Different from the cyclic epidemics observed in some Asia-Pacific regions, there was a continuously high CV-A16 infection rate from 2008 to 2014, and after a period of lower epidemic activity in 2015-2017, an upsurge of CV-A16 infection was observed in 2018-2019. Cocirculation of subgenotypes B1a and B1b was observed, but while subgenotype B1a was predominant from 2008 to 2012, it appears to have been replaced by B1b, which has circulated as the predominant subgenotype since 2013. Phylogenetic analysis showed that most of the circulating CV-A16 strains are endemic, with occasional transmission between neighboring regions. The re-emergence of B1a in 2016-2019 in Guangdong was likely the result of introduction(s) from Southeast Asia. These results highlight the importance of continuous molecular surveillance from different areas, which will improve our understanding of the origin of the epidemic and facilitate the development of strategies for HFMD disease control.

High-coverage SARS-CoV-2 genome sequences acquired by target capture sequencing.

In this study, we designed a set of SARS-CoV-2 enrichment probes to increase the capacity for sequence-based virus detection and obtain the comprehensive genome sequence at the same time. This universal SARS-CoV-2 enrichment probe set contains 502 120 nt single-stranded DNA biotin-labeled probes designed based on all available SARS-CoV-2 viral sequences and it can be used to enrich for SARS-CoV-2 sequences without prior knowledge of type or subtype. Following the CDC health and safety guidelines, marked enrichment was demonstrated in a virus strain sample from cell culture, three nasopharyngeal swab samples (cycle threshold [Ct ] values: 32.36, 36.72, and 38.44) from patients diagnosed with COVID-19 (positive control) and four throat swab samples from patients without COVID-19 (negative controls), respectively. Moreover, based on these high-quality sequences, we discuss the heterozygosity and viral expression during coronavirus replication and its phylogenetic relationship with other selected high-quality samples from the Genome Variation Map. Therefore, this universal SARS-CoV-2 enrichment probe system can capture and enrich SARS-CoV-2 viral sequences selectively and effectively in different samples, especially clinical swab samples with a relatively low concentration of viral particles.

Association of GII.P16-GII.2 Recombinant Norovirus Strain with Increased Norovirus Outbreaks, Guangdong, China, 2016.

An unusual prevalence of recombinant GII.2 noroviruses (GII.P16-GII.2) in Guangdong, China, at the end of 2016 caused a sharp increase in outbreaks of acute gastroenteritis. This event was another non-GII.4 epidemic that emerged after the GII.17 viruses in 2014 and 2015 and warrants global surveillance.

The Evolution and Transmission of Epidemic GII.17 Noroviruses.

BACKGROUND: In recent decades, the GII.4 norovirus genotype has predominated in epidemics worldwide and been associated with an increased rate of evolutionary change. In 2014, a novel GII.17 variant emerged and persisted, causing large outbreaks of gastroenteritis in China and sporadic infections globally. The origin, evolution, and transmission history of this new variant are largely unknown. METHODS: We generated 103 full capsid and 8 whole-genome sequences of GII.17 strains collected between August 2013 and November 2015 in Guangdong, China. Phylogenetic analyses were performed by integrating our data with those for all publically available GII.17 sequences. RESULTS: The novel emergent lineage GII.17_Kawasaki_2014 most likely originated from Africa around 2001 and evolved at a rate of 5.6 × 10(-3) substitutions/site/year. Within this lineage, a new variant containing several important amino acid changes emerged around August 2013 and caused extensive epidemics in 2014-2015. The phylodynamic and epidemic history of the GII.17_Kawasaki lineage shows similarities with the pattern observed for GII.4 norovirus evolution. Virus movements from Hong Kong to neighboring coastal cities were frequently observed. CONCLUSIONS: Our results provide new insights into GII.17 norovirus evolution and transmission and highlight the potential for a rare norovirus genotype to rapidly replace existing strains and cause local epidemics.

Nationwide distribution of varicella-zoster virus clades in China.

BACKGROUND: In 2010, a universal nomenclature for varicella-zoster virus (VZV) clades was established, which is very useful in the monitoring of viral evolution, recombination, spread and genetic diversity. Currently, information about VZV clades has been disclosed worldwide, however, there are limited data regarding the characterization of circulating VZV clades in China, even where varicella remains widely epidemic. METHODS: From 2008 to 2012, clinical samples with varicella or zoster were collected in General Hospital in eight provinces and analyzed by PCR, restriction endonuclease digestion and sequencing. The viral clades were determined by analysis of five single nucleotide polymorphisms (SNPs) within the 447-bp fragment of open reading frame (ORF) 22, and the restriction fragment length polymorphisms (RFLPs) of ORF 38 (PstI), ORF 54 (BglI) and ORF 62 (SmaI) were evaluated to understand genetic diversity of VZV and determinate varicella vaccine adverse event (VVAE). RESULTS: Seventy-seven varicella and 11 zoster samples were identified as being positive for VZV. The five SNPs profile showed that the majority of VZV strains belonged to clade 2, but clade 5 and clade 4 strains were also found in Guangdong. The RFLPs analysis of the DNA fragments of ORF 38, 54 and 62 showed that 85 of these samples were characterized as PstI + BglI + SamI-, and the remaining three VZV strains from varicella patients were characterized as PstI-BglI + SamI+ which is the genetic profile of VVAEs. CONCLUSIONS: The study suggested that the predominant clade 2 VZVs had been continually circulating since at least the 1950s in China. Nearly all VZV strains except VVAEs possessed the genetic profile of PstI + BglI + Sam-. However, the other clades were also found to be co-circulating with clade 2, especially in the border regions. These results highlighted the need for the constant and broad use of virologic surveillance to provide an important genetic baseline for varicella control and vaccination programs in China.

Gastroenteritis Outbreaks Caused by Norovirus GII.17, Guangdong Province, China, 2014-2015.

In the past decade, the most prevalent norovirus genotype causing viral gastroenteritis outbreaks worldwide, including China, has been GII.4. In winter 2014-15, norovirus outbreaks in Guangdong, China, increased. Sequence analysis indicated that 82% of the outbreaks were caused by a norovirus GII.17 variant.

Elucidation of echovirus 30's origin and transmission during the 2012 aseptic meningitis outbreak in Guangdong, China, through continuing environmental surveillance.

An aseptic meningitis outbreak occurred in Luoding City of Guangdong, China, in 2012, and echovirus type 30 (ECHO30) was identified as the major causative pathogen. Environmental surveillance indicated that ECHO30 was detected in the sewage of a neighboring city, Guangzhou, from 2010 to 2012 and also in Luoding City sewage samples (6/43, 14%) collected after the outbreak. In order to track the potential origin of the outbreak viral strains, we sequenced the VP1 genes of 29 viral strains from clinical patients and environmental samples. Sequence alignments and phylogenetic analyses based on VP1 gene sequences revealed that virus strains isolated from the sewage of Guangzhou and Luoding cities matched well the clinical strains from the outbreak, with high nucleotide sequence similarity (98.5% to 100%) and similar cluster distribution. Five ECHO30 clinical strains were clustered with the Guangdong environmental strains but diverged from strains from other regions, suggesting that this subcluster of viruses most likely originated from the circulating virus in Guangdong rather than having been more recently imported from other regions. These findings underscore the importance of long-term, continuous environmental surveillance and genetic analysis to monitor circulating enteroviruses.

Serological investigation on the prevalence of poliovirus in Guangdong province: A cross-sectional study.

In 2019, we conducted a cross-sectional study for polio virus seroprevalence in Guangdong province, China. We assessed the positivity rates of poliomyelitis NA and GMT in serum across various demographic groups, and the current findings were compared with pre-switch data from 2014. Using multistage random sampling method, four counties/districts were randomly selected per city, and within each, one general hospital and two township hospitals were chosen. Healthy individuals coming for medical checkups or vaccination were invited. A total of 1318 individual samples were collected and tested. In non-newborn population, age-dependent positivity rates ranged from 77.8% to 100% for PV1 NA and 70.3% to 98.9% for PV3 NA (p < .01). The lowest GMT values for both types (17.03 and 8.46) occurred in the 20 to <30 years age group, while peak GMTs for PV1 and PV3 were observed in 1 to <2 (340.14) and 0 to <1-year (168.90) age groups, respectively. GMTs for PV1 (P = .002) and PV3 (P = .007) in Eastern Guangdong were lower than those in the other three regions. Male participants showed higher GMTs than females (P = .016 and .033, respectively). In newborn population, both males and females showed higher PV1 NA positivity rates and GMTs compared to PV3 (p < .05). Post-switch PV3 NA positivity rates were higher than pre-switch rates (p = .016). GMTs of both PV1 and PV3 were significantly higher post-switch (p < .001). The positivity rates of NAs and GMTs remain high level, which play an important role in resisting poliomyelitis infection. Effect of the converted immunization program was more pronounced than that before.

Prevalence of nonpolio enteroviruses in the sewage of Guangzhou city, China, from 2009 to 2012.

The human-pathogenic viruses in urban sewage have been extensively monitored to obtain information on circulating viruses in human communities. Enteroviruses (EVs) excreted by patients who present with diverse clinical syndromes can remain infectious in the environment for several weeks, and limited data on circulating environmental EVs are available. A 4-year (2009 to 2012) surveillance study was conducted to detect nonpolio enteroviruses (NPEVs) in the urban sewage of Guangzhou city, China. After the viruses in the sewage samples were concentrated and isolated, molecular identification was used to detect and type the NPEVs. During the 4-year study, 17 different NPEV serotypes were identified in the sewage of Guangzhou city. The most common serotypes were echovirus 11 (ECHO11), ECHO6, ECHO7, and ECHO12 and coxsackie group B viruses 5 (CVB5) and CVB3. The predominant serotypes were influenced by spatial and temporal factors and differed each year. CVB5 was commonly detected in 2009 and 2010 but was rarely isolated in 2011 and 2012. In contrast, CVB3 was not observed in 2009 and 2010 but was increasingly detected in 2011 and 2012. Our study provides an overview of the serotype distribution and circulation patterns of NPEVs in the sewage of Guangzhou, China. In the absence of a systematic EV disease surveillance system, the detection and characterization of sewage-borne NPEVs will help us better understand the changes in EV disease trends and the epidemic background of circulating EVs, which could help interpret the EV trends and warn of future outbreaks in this area.

Prevalence of Non-Polio Enteroviruses in the Sewage of Guangzhou City, China, from 2013 to 2021.

Continuous surveillance of enteroviruses (EVs) in urban domestic sewage can timely reflect the circulation of EVs in the environment and crowds, and play a predictive and early warning role in EV-related diseases. To better understand the long-term epidemiological trends of circulating EVs and EV-related diseases, we conducted a 9-year (2013 to 2021) surveillance study of non-polio EVs (NPEVs) in urban sewage in Guangzhou city, China. After concentrating and isolating the viruses from the sewage samples, NPEVs were detected and molecular typing was performed. Twenty-one different NPEV serotypes were identified. The most isolated EVs were echovirus 11 (E11), followed by coxsackievirus (CV) B5, E6, and CVB3. EV species B prevailed in sewage samples, but variations in the annual frequency of different serotypes were also observed in different seasons, due to spatial and temporal factors. E11 and E6 were detected continuously before 2017, and the number of isolates was relatively stable during the surveillance period. However, after their explosive growth in 2018 and 2019, their numbers suddenly decreased significantly. CVB3 and CVB5 had alternating trends; CVB5 was most frequently detected in 2013 to 2014 and 2017 to 2018, while CVB3 was most frequently detected in 2015 to 2016 and 2020 to 2021. Phylogenetic analysis showed that at least two different transmission chains of CVB3 and CVB5 were prevalent in Guangzhou City. Our results show that in the absence of a comprehensive and systematic EV-related disease surveillance system in China, environmental surveillance is a powerful and effective tool to strengthen and further investigate the invisible transmission of EVs in the population. IMPORTANCE This study surveilled urban sewage samples from north China for 9 years to monitor enteroviruses. Samples were collected, processed, and viral identification and molecular typing were performed. We detected 21 different non-polio enteroviruses (NPEVs) with yearly variations in prevalence and peak seasons. In addition, this study is very important for understanding the epidemiology of EVs during the COVID-19 pandemic, as the detection frequency and serotypes of EVs in sewage changed considerably around 2020. We believe that our study makes a significant contribution to the literature because our results strongly suggest that environmental surveillance is an exceptionally important tool, which can be employed to detect and monitor organisms of public health concern, which would otherwise be missed and under-reported by case-based surveillance systems alone.

Emergence and continuous evolution of genotype 1E rubella viruses in China.

In China, rubella vaccination was introduced into the national immunization program in 2008, and a rubella epidemic occurred in the same year. In order to know whether changes in the genotypic distribution of rubella viruses have occurred in the postvaccination era, we investigate in detail the epidemiological profile of rubella in China and estimate the evolutionary rate, molecular clock phylogeny, and demographic history of the predominant rubella virus genotypes circulating in China using Bayesian Markov chain Monte Carlo phylodynamic analyses. 1E was found to be the predominant rubella virus genotype since its initial isolation in China in 2001, and no genotypic shift has occurred since then. The results suggest that the global 1E genotype may have diverged in 1995 and that it has evolved at a mutation rate of 1.65 × 10(-3) per site per year. The Chinese 1E rubella virus isolates were grouped into either cluster 1 or cluster 2, which likely originated in 1997 and 2006, respectively. Cluster 1 viruses were found in all provinces examined in this study and had a mutation rate of 1.90 × 10(-3) per site per year. The effective number of infections remained constant until 2007, and along with the introduction of rubella vaccine into the national immunization program, although the circulation of cluster 1 viruses has not been interrupted, some viral lineages have disappeared, and the epidemic started a decline that led to a decrease in the effective population size. Cluster 2 viruses were found only in Hainan Province, likely because of importation.