Reassortment and genomic analysis of a G9P[8]-E2 rotavirus isolated in China.

OBJECTIVE: To isolate a prevalent G9P[8] group A rotavirus (RVA) (N4006) in China and investigate its genomic and evolutionary characteristics, with the goal of facilitating the development of a new rotavirus vaccine. METHODS: The RVA G9P[8] genotype from a diarrhea sample was passaged in MA104 cells. The virus was evaluated by TEM, polyacrylamide gel electrophoresis, and indirect immunofluorescence assay. The complete genome of virus was obtained by RT-PCR and sequencing. The genomic and evolutionary characteristics of the virus were evaluated by nucleic acid sequence analysis with MEGA ver. 5.0.5 and DNASTAR software. The neutralizing epitopes of VP7 and VP4 (VP5* and VP8*) were analyzed using BioEdit ver. 7.0.9.0 and PyMOL ver. 2.5.2. RESULTS: The RVA N4006 (G9P[8] genotype) was adapted in MA104 cells with a high titer (105.5 PFU/mL). Whole-genome sequence analysis showed N4006 to be a reassortant rotavirus of Wa-like G9P[8] RVA and the NSP4 gene of DS-1-like G2P[4] RVA, with the genotype constellation G9-P[8]-I1-R1-C1-M1-A1-N1-T1-E2-H1 (G9P[8]-E2). Phylogenetic analysis indicated that N4006 had a common ancestor with Japanese G9P[8]-E2 rotavirus. Neutralizing epitope analysis showed that VP7, VP5*, and VP8* of N4006 had low homology with vaccine viruses of the same genotype and marked differences with vaccine viruses of other genotypes. CONCLUSION: The RVA G9P[8] genotype with the G9-P[8]-I1-R1-C1-M1-A1-N1-T1-E2-H1 (G9P[8]-E2) constellation predominates in China and may originate from reassortment between Japanese G9P[8] with Japanese DS-1-like G2P[4] rotaviruses. The antigenic variation of N4006 with the vaccine virus necessitates an evaluation of the effect of the rotavirus vaccine on G9P[8]-E2 genotype rotavirus.

The induction and suppression of type I and type III interferons by human group H rotavirus.

Group H Rotavirus (RVH) is associated with human diarrhea gastroenteritis. The interferon (IFN) response induced by RVH remains unclear. In this study, we first studied the characteristic feature of RVH and found J19 strain of RVH grew less efficiently compared with the G6P1 strain of RVA. Next, we found that infection with the J19 virus resulted in the secretion of IFN-λ1, but not IFN-ß, while both IFN-ß and IFN-λ1 could inhibit J19 replication significantly in Caco-2 cells. NSP1 played an important role in the suppression of type I and type III IFN response, and NSP5 protein significantly inhibited activation of IFN-λ1. J19 NSP1 suppressed the induction of IFN-ß obviously than G6P1 NSP1, while G6P1 NSP1 reduced IFN-λ1 induction to the greatest extent compared with G9P8, Wa, and J19 NSP1s. Our studies reveal the propagation feature of RVH and interferon induction and suppression by group H rotavirus.

Genomic and evolutionary characteristics of G9P[8], the dominant group a rotavirus in China (2016-2018).

G9P[8] became the predominant rotavirus A (RVA) genotype in China in 2012. To evaluate its genetic composition at the whole-genome level, 115 G9P[8] RVA strains isolated from children under 5 years old were sequenced and characterized. All 13 strains in 2016 and 2017 and an additional 54 strains in 2018 were genotyped as G9-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1. The other 48 strains in 2018 were all genotyped as G9-P[8]-I1-R1-C1-M1-A1-N1-T1-E2-H1, with the NSP4 gene characterized as a DS-1-like genotype. The time of the most recent common ancestor (tMRCA) and evolution rates of the VP7, VP4, and NSP4 (E1 and E2) genes of these strains were estimated by Bayesian evolutionary dynamics analysis. We estimated the evolution rates (nt substitutions per site per year) as 1.38 × 10-3 [the 95% highest posterior density (HPD) was 1.09-1.72 × 10-3] for VP7, 0.87 × 10-3 (95% HPD: 0.75-1.00 × 10-3) for VP4, 0.56 × 10-3 (95% HPD: 0.41-0.73 × 10-3) for NSP4-E1, and 1.35 × 10-3 (95% HPD: 0.92-1.86 × 10-3) for NSP4-E2. The tMRCA was estimated to be 1935.4 (95% HPD: 1892.4-1961.3) for VP7, 1894.3 (95% HPD: 1850.5-1937.8) for VP4, 1929.4 (95% HPD: 1892.4-1961.3) for NSP4-E1, and 1969.2 (95% HPD: 1942.2-1985.3) for NSP4-E2. The baseline genetic information in this study is expected to improve our understanding of the genomic and evolutionary characteristics of the rotavirus genome. Furthermore, it will provide a basis for the development of next-generation rotavirus vaccines for humans.

Phylogenetic analysis of the viral proteins VP4/VP7 of circulating human rotavirus strains in China from 2016 to 2019 and comparison of their antigenic epitopes with those of vaccine strains.

Group A rotaviruses (RVAs) are the most common etiological agents of severe acute diarrhea among children under 5 years old worldwide. At present, two live-attenuated RVA vaccines, LLR (G10P[15]) and RotaTeq (G1-G4, G6 P[8], P[5]), have been introduced to mainland China. Although RVA vaccines can provide homotypic and partially heterotypic protection against several strains, it is necessary to explore the genetic and antigenic variations between circulating RVAs and vaccine strains. In this study, we sequenced viral protein VP7 and VP4 outer capsid proteins of 50 RVA strains circulating in China from 2016 to 2019. The VP7 and VP4 sequences of almost all strains showed high homology to those of previously reported human strains and vaccine strains of the same genotype. However, in the presumed antigenic epitopes of the VP7 and VP4, multiple amino acid variations were found, regardless of the G and P genotypes of these strains. Moreover, all circulating G3 RVA strains in China potentially possess an extra N-linked glycosylation site compared with the G3 strain of RotaTeq. The potential N-linked glycosylation site at residues 69-71 was found in all G9 strains in China but not in the G9 strain of the Rotavac or Rotasill vaccine. These variations in antigenic sites might result in the selection of strains that escape the RVA neutralizing-antibody pressure imposed by vaccines. Furthermore, the G4 and P[6] genotypes in this study showed high homology to those of porcine strains, indicating the transmission of G4 and P[6] genotypes from pigs to humans in China. More genetic surveillance with antigenic evaluation in prevalent RVAs is necessary for developing and implementing rotavirus vaccines in China.

Genomic and evolutionary characteristics of G3P[8] group a rotavirus strains in China, 2016 to 2018.

Rotavirus A (RVA) G3P[8] is sporadically detected in China, although G9P[8] predominates. To evaluate their genetic composition at the whole-genome level, 24 G3P[8] RVA strains isolated from children under five years were sequenced and characterized. The 24 strains were genotyped as G3-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1, indicating the Wa-like genotype constellation. A maximum clade credibility (MCC) tree for VP7 indicated that G3 had an estimated mean evolutionary rate of 7.279 × 10-4 substitutions/site/year; thus, 3-5 years would pass from the generation of an ancestor virus to the epidemic spread of that virus throughout China. Considering the ongoing prevalence as well as rapid evolution, it is important to monitor G3P[8] RVA epidemics; continuous nationwide surveillance is essential.

Structural and functional characterization of bovine G1P[5] rotavirus VP8* protein.

The widely used rotavirus (RV) vaccine, Rotateq, contained reassortment strains of human and bovine G1/2/3/4P[5] RVs. The functional and structural features of bovine G1P[5] VP8* were investigated. Bovine G1P[5] VP8* was identified to interact with sialic acids and sialic acid-containing glycans. In addition, P[5] VP8* recognized α-Gal histo-blood group antigens (HBGAs). Bovine G1P[5] VP8* did not hemagglutinate the tested red blood cells. The crystal structure of P[5] VP8* was determined at 1.7 Å. Structural superimposition revealed that P[5] VP8* was most close to human P[8] VP8*, while much further to VP8*s of porcine P[7] and rhesus P[3]. Sequence alignment showed that amino acids of the putative glycan binding site in P[5] VP8* were different to those in P[3]/P[7] VP8*s, indicating that P[5] VP8* may interact with glycans using different mechanism. This study provided more understanding of P[5] RV infection and the interactions of RV VP8* and glycans.

Structural Basis of Glycan Recognition of Rotavirus.

Rotavirus (RV) is an important pathogen causing acute gastroenteritis in young humans and animals. Attachment to the host receptor is a crucial step for the virus infection. The recent advances in illustrating the interactions between RV and glycans promoted our understanding of the host range and epidemiology of RVs. VP8*, the distal region of the RV outer capsid spike protein VP4, played a critical role in the glycan recognition. Group A RVs were classified into different P genotypes based on the VP4 sequences and recognized glycans in a P genotype-dependent manner. Glycans including sialic acid, gangliosides, histo-blood group antigens (HBGAs), and mucin cores have been reported to interact with RV VP8*s. The glycan binding specificities of VP8*s of different RV genotypes have been studied. Here, we mainly discussed the structural basis for the interactions between RV VP8*s and glycans, which provided molecular insights into the receptor recognition and host tropism, offering new clues to the design of RV vaccine and anti-viral agents.

The Functional Characterization of Bat and Human P[3] Rotavirus VP8*s.

P[3] rotavirus (RV) has been identified in many species, including human, simian, dog, and bat. Several glycans, including sialic acid, histo-blood group antigens (HBGAs) are reported as RV attachment factors. The glycan binding specificity of different P[3] RV VP8*s were investigated in this study. Human HCR3A and dog P[3] RV VP8*s recognized glycans with terminal sialic acid and hemagglutinated the red blood cells, while bat P[3] VP8* showed neither binding to glycans nor hemagglutination. However, the bat P[3] VP8* mutant of C189Y obtained the ability to hemagglutinate the red blood cells, while human P[3] HCR3A/M2-102 mutants of Y189C lost the ability. Sequence alignment and structural analysis indicated that residue 189 played an important role in the ligand recognition and may contribute to the cross-species transmission. Structural superimposition exhibited that bat P[3] VP8* model was quite different from the simian P[3] Rhesus rotavirus (RRV) P[3] VP8*, indicating that bat P[3] RV was relatively distinct and partially contributed to the no binding to tested glycans. These results promote our understanding of P[3] VP8*/glycans interactions and the potential transmission of bat/human P[3] RVs, offering more insight into the RV infection and prevalence.

Infection status and circulating strains of rotaviruses in Chinese children younger than 5-years old from 2011 to 2018: systematic review and meta-analysis.

To evaluate rotavirus (RV) disease burden and circulating strains of RV among Chinese children younger than 5-years old who had diarrhea from 2011 to 2018. PubMed, Web of Science, Embase, CNKI and WANFANG databases were systematically searched to identify studies that reported RV prevalence in mainland China. After data extraction, a fixed-effects model or a random-effects model was applied to estimate RV positivity and proportions of G and P types. Statistical analysis was conducted using R software. We initially reviewed 1323 studies, and identified 69 studies that were eligible. The overall proportion of RV gastroenteritis (RVGE) among children under 5-years old who presented with diarrhea and sought medical care was 34.0% (95% CI: 31.3, 36.8), and RV positivity was higher among inpatients (39.7%) than outpatients (23.9%). Western areas of China had the highest proportion of RVGE (42.7%), and RV positivity was highest for children who were 6 months-old to 2 years-old. The most prevalent G types were G3 (26.1%), G9 (17.5%), and G1 (12.8%), the most prevalent P type was P[8] (56.8%) and the most prevalent G-P combination was G9P[8] (20.9%). RV continues to be a main cause of acute gastroenteritis in Chinese children who are younger than 5 years old. Following the introduction of an RV vaccine in 2011, monitoring of the disease burden of RV diarrhea and circulating strains in China remain important for assessments of vaccine efficacy.

Human group A rotavirus P[25] VP8* specifically binds to A-type histo-blood group antigen.

Rotavirus (RV) is a common cause of acute gastroenteritis in young children. While P[8] and P[4] are the most prevalent RV genotypes in humans, other genotypes are also reported in human infections occasionally, including human P[25]. The glycan binding and structural characteristics of human P[25] were explored in our study. Human P[25] VP8* recognized type A histo-blood group antigen (HBGA) in the glycan microarray/oligosaccharide binding assay and could specifically hemagglutinate type A blood cells. Moreover, the P[25] VP8* structure was determined at 2.6 Å, revealing a similar conformation and a conserved putative glycan binding site as that of P[14] VP8*. This study provided further knowledge of the glycan binding and structural features of P[25] RV VP8*, promoting our understanding of the infection, prevalence, and host range of the P[III] RVs.

A novel picornavirus identified in wild Macaca mulatta in China.

The discovery of novel viruses in wild animals allows the prediction of their potential threat to the health of humans and other animals. We report a highly divergent picornavirus (tentatively named "mobovirus A"), identified in a fecal sample from Macaca mulatta in Yunnan province, China, using viral metagenomic analysis, with viral loads of 2 × 107 copies/g. The complete genomic sequence of mobovirus A is 8,325 nucleotides in length. Phylogenetic analysis showed that it clustered with Guangxi changeable lizard picornavirus 1 and Guangxi Chinese leopard gecko picornavirus, with less than 38%, 40%, and 40% amino acid identity in the P1, P2, and P3 protein, respectively. The viruses in this cluster were most closely related to members of the genera Harkavirus, Tremovirus and Hepatovirus. Genomic analysis revealed that mobovirus A has the typical genomic organization and motifs of a picornavirus. Additionally, its codon usage bias complements that of M. mulatta, suggesting that this feature is not restricted only to hepatoviruses. Thus, according to the guidelines of the Picornaviridae Study Group of the International Committee on Taxonomy of Viruses, mobovirus A should be considered a member of a new genus (tentatively named for Monkey-borne virus, "Mobovirus") in the family Picornaviridae. These data will facilitate the understanding of the genetic diversity and evolution of picornaviruses. Further studies are needed to understand the epidemiology and potential pathogenicity of the virus in M. mulatta.

Structural Basis of Glycan Recognition in Globally Predominant Human P[8] Rotavirus.

Rotavirus (RV) causes acute gastroenteritis in infants and children worldwide. Recent studies showed that glycans such as histo-blood group antigens (HBGAs) function as cell attachment factors affecting RV host susceptibility and prevalence. P[8] is the predominant RV genotype in humans, but the structural basis of how P[8] RVs interact with glycan ligands remains elusive. In this study, we characterized the interactions between P[8] VP8*s and glycans which showed that VP8*, the RV glycan binding domain, recognized both mucin core 2 and H type 1 antigens according to the ELISA-based oligosaccharide binding assays. Importantly, we determined the structural basis of P[8] RV-glycans interaction from the crystal structures of a Rotateq P[8] VP8* in complex with core 2 and H type 1 glycans at 1.8 Å and 2.3 Å, respectively, revealing a common binding pocket and similar binding mode. Structural and sequence analysis demonstrated that the glycan binding site is conserved among RVs in the P[II] genogroup, while genotype-specific amino acid variations determined different glycan binding preference. Our data elucidated the detailed structural basis of the interactions between human P[8] RVs and different host glycan factors, shedding light on RV infection, epidemiology, and development of anti-viral agents.

Profiling of Human Milk Oligosaccharides for Lewis Epitopes and Secretor Status by Electrostatic Repulsion Hydrophilic Interaction Chromatography Coupled with Negative-Ion Electrospray Tandem Mass Spectrometry.

Human milk oligosaccharides (HMOs) are one of the most abundant ingredients in breast milk, and they play a beneficial role for newborns and are important for infant health. The peripheral fucosylated sequences of HMOs, such as the histo-blood group ABH(O) and Lewis a, b, x, and y antigens, are determined by the expression of the secretor (Se) and Lewis (Le) genes in the mammary gland, and are often the recognition motifs and serve as decoy receptors for microbes. In this work, we developed a method for determination of secretor status and Lewis blood phenotype and assignment of Lewis blood-group epitopes. The method was based on electrostatic repulsion/hydrophilic interaction chromatography coupled with tandem mass spectrometry (ERLIC-MS/MS). A specifically designed stationary phase, aspartic acid-bonded silica (ABS), was used to separate the acidic and neutral HMOs by electrostatic repulsion followed by HILIC. Negative-ion electrospray MS/MS was then used for analysis of secretor status and Lewis blood phenotypes and assignment of important epitopes of HMOs from the lactating mothers by selecting a specific set of unique fragment ions.

GII.13/21 Noroviruses Recognize Glycans with a Terminal ß-Galactose via an Unconventional Glycan Binding Site.

Human noroviruses (huNoVs) recognize histo-blood group antigens (HBGAs) as host susceptibility factors. GII.13 and GII.21 huNoVs form a unique genetic lineage that emerged from mainstream GII NoVs via development of a new, nonconventional glycan binding site (GBS) that binds Lea antigen. This previous finding raised the question of whether the new GII.13/21 GBS really has such a narrow glycan binding spectrum. In this study, we provide solid phenotypic and structural evidence indicating that this new GBS recognizes a group of glycans with a common terminal ß-galactose (ß-Gal). First, we found that P domain proteins of GII.13/21 huNoVs circulating at different times bound three glycans sharing a common terminal ß-Gal, including Lec, lactose, and mucin core 2. Second, we solved the crystal structures of the GII.13 P dimers in complex with Lec and mucin core 2, which showed that ß-Gal is the major binding saccharide. Third, nonfat milk and lactose blocked the GII.13/21 P domain-glycan binding, which may explain the low prevalence of GII.13/21 viruses. Our data provide new insight into the host interactions and epidemiology of huNoVs, which would help in the control and prevention of NoV-associated diseases.IMPORTANCE Evidence from both phenotypic binding assay and structural study support the observed interactions of human noroviruses (huNoVs) with histo-blood group antigens (HBGAs) as receptors or attachment factors, affecting their host susceptibility. GII.13 and GII.21 genotypes form a unique genetic lineage that differs from the mainstream GII huNoVs in their unconventional glycan binding site. Unlike the previous findings that GII.13/21 genotypes recognize only Lea antigen, we found in this study that they can interact with a group of glycans with a common terminal ß-Gal, including Lec, lactose, and mucin core 2. However, this wide glycan binding spectrum in a unique binding mode of the GII.13/21 huNoVs appears not to increase their prevalence, probably due to the existence of decoy glycan receptors in human gastrointestinal tract limiting their infection. Our findings shed light on the host interaction and epidemiology of huNoVs, which would impact the strategy of huNoV control and prevention.

Glycan binding patterns of human rotavirus P[10] VP8* protein.

BACKGROUND: Rotaviruses (RVs) are a major cause of acute children gastroenteritis. The rotavirus P [10] belongs to P[I] genogroup of group A rotaviruses that mainly infect animals, while the rotavirus P [10] was mainly identified from human infection. The rotavirus P [10] is an unusual genotype and the recognition pattern of cellular receptors remains unclear. METHODS: We expressed and purified the RV P [10] VP8* protein and investigated the saliva and oligosaccharide binding profiles of the protein. A homology model of the P [10] VP8* core protein was built and the superimposition structural analysis of P [10] VP8* protein on P [19] VP8* in complex with mucin core 2 was performed to explore the possible docking structural basis of P [10] VP8* and mucin cores. RESULTS: Our data showed that rotavirus P [10] VP8* protein bound to all ABO secretor and non-secretor saliva. The rotavirus P [10] could bind strongly to mucin core 2 and weakly to mucin core 4. The homology modeling indicated that RV P [10] VP8* binds to mucin core 2 using a potential glycan binding site that is the same to P [19] VP8* belonging to P[II] genogroup. CONCLUSION: Our results suggested an interaction of rotavirus P [10] VP8* protein with mucin core 2 and mucin core 4. These findings offer potential for elucidating the mechanism of RV A host specificity, evolution and epidemiology.

Glycan Binding Specificity and Mechanism of Human and Porcine P[6]/P[19] Rotavirus VP8*s.

Rotaviruses (RVs), which cause severe gastroenteritis in infants and children, recognize glycan ligands in a genotype-dependent manner via the distal VP8* head of the spike protein VP4. However, the glycan binding mechanisms remain elusive for the P[II] genogroup RVs, including the widely prevalent human RVs (P[8], P[4], and P[6]) and a rare P[19] RV. In this study, we characterized the glycan binding specificities of human and porcine P[6]/P[19] RV VP8*s and found that the P[II] genogroup RV VP8*s could commonly interact with mucin core 2, which may play an important role in RV evolution and cross-species transmission. We determined the first P[6] VP8* structure, as well as the complex structures of human P[19] VP8*, with core 2 and lacto-N-tetraose (LNT). A glycan binding site was identified in human P[19] VP8*. Structural superimposition and sequence alignment revealed the conservation of the glycan binding site in the P[II] genogroup RV VP8*s. Our data provide significant insight into the glycan binding specificity and glycan binding mechanism of the P[II] genogroup RV VP8*s, which could help in understanding RV evolution, transmission, and epidemiology and in vaccine development.IMPORTANCE Rotaviruses (RVs), belonging to the family Reoviridae, are double-stranded RNA viruses that cause acute gastroenteritis in children and animals worldwide. Depending on the phylogeny of the VP8* sequences, P[6] and P[19] RVs are grouped into genogroup II, together with P[4] and P[8], which are widely prevalent in humans. In this study, we characterized the glycan binding specificities of human and porcine P[6]/P[19] RV VP8*s, determined the crystal structure of P[6] VP8*, and uncovered the glycan binding pattern in P[19] VP8*, revealing a conserved glycan binding site in the VP8*s of P[II] genogroup RVs by structural superimposition and sequence alignment. Our data suggested that mucin core 2 may play an important role in P[II] RV evolution and cross-species transmission. These data provide insight into the cell attachment, infection, epidemiology, and evolution of P[II] genogroup RVs, which could help in developing control and prevention strategies against RVs.

Human Group C Rotavirus VP8*s Recognize Type A Histo-Blood Group Antigens as Ligands.

Group/species C rotaviruses (RVCs) have been identified as important pathogens of acute gastroenteritis (AGE) in children, family-based outbreaks, as well as animal infections. However, little is known regarding their host-specific interaction, infection, and pathogenesis. In this study, we performed serial studies to characterize the function and structural features of a human G4P[2] RVC VP8* that is responsible for the host receptor interaction. Glycan microarrays demonstrated that the human RVC VP8* recognizes type A histo-blood group antigens (HBGAs), which was confirmed by synthetic glycan-/saliva-based binding assays and hemagglutination of red blood cells, establishing a paradigm of RVC VP8*-glycan interactions. Furthermore, the high-resolution crystal structure of the human RVC VP8* was solved, showing a typical galectin-like structure consisting of two ß-sheets but with significant differences from cogent proteins of group A rotaviruses (RVAs). The VP8* in complex with a type A trisaccharide displays a novel ligand binding site that consists of a particular set of amino acid residues of the C-D, G-H, and K-L loops. RVC VP8* interacts with type A HBGAs through a unique mechanism compared with that used by RVAs. Our findings shed light on the host-virus interaction and the coevolution of RVCs and will facilitate the development of specific antivirals and vaccines.IMPORTANCE Group/species C rotaviruses (RVCs), members of Reoviridae family, infect both humans and animals, but our knowledge about the host factors that control host susceptibility and specificity is rudimentary. In this work, we characterized the glycan binding specificity and structural basis of a human RVC that recognizes type A HBGAs. We found that human RVC VP8*, the rotavirus host ligand binding domain that shares only ∼15% homology with the VP8* domains of RVAs, recognizes type A HBGA at an as-yet-unknown glycan binding site through a mechanism distinct from that used by RVAs. Our new advancements provide insights into RVC-cell attachment, the critical step of virus infection, which will in turn help the development of control and prevention strategies against RVs.

Faecal shedding of rotavirus vaccine in Chinese children after vaccination with Lanzhou lamb rotavirus vaccine.

Lanzhou lamb rotavirus vaccine (LLR) is an oral live attenuated vaccine first licensed in China in 2000. To date, > 60 million doses of LLR have been distributed to children. However, very little is known about faecal shedding of LLR in children. Therefore, faecal samples (n = 1,184) were collected from 114 children for 15 days post-vaccination in September-November 2011/2012. Faecal shedding and viral loads were determined by an enzyme immunoassay kit (EIA) and real-time RT-PCR. The complete genome was sequenced and the vaccine strain was isolated by culture in MA104 cells. Approximately 14.0% (16/114) of children had rotavirus-positive samples by EIA for at least 1 day post-vaccination. Viral loads in EIA-positive samples ranged from < 1.0 × 103 to 1.9 × 108 copies/g. Faecal shedding occurred as early as post-vaccination day 2 and as late as post-vaccination day 13 and peaked on post-vaccination day 5-10. One LLR strain was isolated by culture in MA104 cells. Sequence analysis showed 99% identity with LLR prototype strain. Faecal shedding of LLR in stool is common within 15 days of LLR vaccination, indicating vaccine strains can replicate in human enteric tissues.

Quantitative detection of human Malawi polyomavirus in nasopharyngeal aspirates, sera, and feces in Beijing, China, using real-time TaqMan-based PCR.

BACKGROUND: Human Malawi polyomavirus (MWPyV) was discovered in 2012, but its prevalence and clinical characteristics are largely unknown. METHODS: We used real-time TaqMan-based PCR to detect MWPyV in the feces (n = 174) of children with diarrhea, nasopharyngeal aspirates (n = 887) from children with respiratory infections, and sera (n = 200) from healthy adults, and analyzed its clinical characteristics statistically. All the MWPyV-positive specimens were also screened for other common respiratory viruses. RESULTS: Sixteen specimens were positive for MWPyV, including 13 (1.47%) respiratory samples and three (1.7%) fecal samples. The samples were all co-infected with other respiratory viruses, most commonly with influenza viruses (69.2%) and human coronaviruses (30.7%). The MWPyV-positive children were diagnosed with bronchopneumonia or viral diarrhea. They ranged in age from 12 days to 9 years, and the most frequent symptoms were cough and fever. CONCLUSIONS: Real-time PCR is an effective tool for the detection of MWPyV in different types of samples. MWPyV infection mainly occurs in young children, and fecal-oral transmission is a possible route of its transmission.