Objective:To investigate the clinical manifestation, therapy, and prognosis of Susac syndrome and enhance the understanding of this disease.Methods:A case summary was made.The clinical data of two siblings with Susac syndrome treated at Children′s Medical Center, Peking University First Hospital in January 2024 were summarized.Reported cases of pediatric Susac syndrome were reviewed.Results:The onset of the disease in the two siblings was at the age of 3.00 and 6.75 years, with recurrent headaches, tinnitus, hearing loss and encephalopathy symptoms.Cranial magnetic resonance imaging showed multiple cerebral microbleeding and microinfarction lesions, " snowball like" in the corpus callosum and diffuse white matter edema in the brain.Audiometry revealed sensorineural hearing loss.In one case, ophthalmic fluorescein angiography revealed ischemic changes due to branch retinal artery occlusions.No pathogenic variants were detected in gene testing.This child was diagnosed with Susac syndrome, and the symptoms were improved after treatment with Corticosteroids and Rituximab.No relapse was observed during the 9-month follow-up.A total of 20 pediatric cases of Susac syndrome were retrieved, including 18 reported previously and 2 cases from this study.There were 2 boys and 18 girls, with the age of onset ranging from 2.5 to 17.0 years.The common initial symptoms included headache (19 cases), vertigo and tinnitus or hearing loss (9 cases), and vision impairment or visual field defect (4 cases). The symptoms were improved after immunotherapy.Conclusions:With a low incidence, Susac syndrome is rare in children and difficult to diagnose.There may be a genetic predisposition in such disease.Early diagnosis and immunotherapy can low the relapse and improve the prognosis.

Objective:To identify strain-specific features of Klebsiella pneumoniae by analyzing metagenomics next generation sequencing (mNGS) data, thereby expanding the downstream applications of mNGS. Methods:The sequences of K.pneumoniae strains were organized from both the self-built database of the long-term multi-center research cohort in China established by the Peking University People′s Hospital from 2009 to 2020 (with 2 345 sequences) and the public databases (with 19 648 sequences). The existing large-scale databases were compressed, and a set of strains representative of clonal groups were screened. A strain genome information library was constructed based on k-mer features, and the most matching representative sequences in the database were searched for the raw mNGS data. The search results of the self-built library and public library were merged and optimized to update the prediction of antimicrobial-resistance characteristics and avoid the impact of uneven data distribution on the results. A total of 314 clinical samples from patients with K.pneumoniae detected by mNGS in the Clinical Microbiology Laboratory of Peking University People′s Hospital from 2022 to 2024 were retrospectively collected, and 101 samples with positive clinical culture results were selected to validate the prediction results. The antimicrobial-resistance phenotypes were verified by clinical antimicrobial susceptibility test results. Whole-genome sequencing was performed on the culture strains of 14 samples randomly selected using random numbers to verify the genotypes. Single nucleotide polymorphism distance analysis was used to verify the occurrence of outbreak events. The χ2 test and Mann-Whitney U test were used for statistical analysis. Results:A representative strain sequence k-mer feature library containing self-built and public sub-libraries was constructed. The library construction required only about 1 hour with <3 GB storage, with a high compression ratio and low update cost. Using k-mer-based analysis, mNGS data achieved precise strain characterization within 4 minutes and and <5 GB memory occupation. There was a significant difference in the antimicrobial-resistance rates to more than half of the antibiotics between the self-built database (90.8%, 2 130/2 345) and the public database (22.7%, 4 457/19 648) ( χ2=4 634.1, P<0.001). After optimizing the search results, the mean category agreement, sensitivity, and specificity of the prediction for eight antibiotics reached 84.8% (323/381), 78.9% (131/166), and 91.2% (196/215), respectively. The target genotypes were successfully detected in 10 out of 12 samples, and two outbreak events (2 samples per event) were successfully identified. Conclusions:An independent analysis process adapted to the needs of identifying the features of K. pneumoniae strains in mNGS data was developed. This process requires minimal computational resources and processing time and can directly achieve the simultaneous analysis of the antimicrobial-resistance phenotypes of K. pneumoniae at the strain level and their corresponding genomic characteristic profiles based on the raw mNGS reads.

The continuous emergence of SARS-CoV-2 variants as well as other potential future coronavirus has challenged the effectiveness of current COVID-19 vaccines. Therefore, there remains a need for alternative antivirals that target processes less susceptible to mutations, such as the formation of six-helix bundle (6-HB) during the viral fusion step of host cell entry. In this study, a novel high-throughput screening (HTS) assay employing a yeast-two-hybrid (Y2H) system was established to identify inhibitors of HR1/HR2 interaction. The compound IMB-9C, which achieved single-digit micromolar inhibition of SARS-CoV-2 and its Omicron variants with low cytotoxicity, was selected. IMB-9C effectively blocks the HR1/HR2 interaction in vitro and inhibits SARS-CoV-2-S-mediated cell-cell fusion. It binds to both HR1 and HR2 through non-covalent interaction and influences the secondary structure of HR1/HR2 complex. In addition, virtual docking and site-mutagenesis results suggest that amino acid residues A930, I931, K933, T941, and L945 are critical for IMB-9C binding to HR1. Collectively, in this study, we have developed a novel screening method for HR1/HR2 interaction inhibitors and identified IMB-9C as a potential antiviral small molecule against COVID-19 and its variants.

Objective:To investigate the clinical manifestation, therapy, and prognosis of Susac syndrome and enhance the understanding of this disease.Methods:A case summary was made.The clinical data of two siblings with Susac syndrome treated at Children′s Medical Center, Peking University First Hospital in January 2024 were summarized.Reported cases of pediatric Susac syndrome were reviewed.Results:The onset of the disease in the two siblings was at the age of 3.00 and 6.75 years, with recurrent headaches, tinnitus, hearing loss and encephalopathy symptoms.Cranial magnetic resonance imaging showed multiple cerebral microbleeding and microinfarction lesions, " snowball like" in the corpus callosum and diffuse white matter edema in the brain.Audiometry revealed sensorineural hearing loss.In one case, ophthalmic fluorescein angiography revealed ischemic changes due to branch retinal artery occlusions.No pathogenic variants were detected in gene testing.This child was diagnosed with Susac syndrome, and the symptoms were improved after treatment with Corticosteroids and Rituximab.No relapse was observed during the 9-month follow-up.A total of 20 pediatric cases of Susac syndrome were retrieved, including 18 reported previously and 2 cases from this study.There were 2 boys and 18 girls, with the age of onset ranging from 2.5 to 17.0 years.The common initial symptoms included headache (19 cases), vertigo and tinnitus or hearing loss (9 cases), and vision impairment or visual field defect (4 cases). The symptoms were improved after immunotherapy.Conclusions:With a low incidence, Susac syndrome is rare in children and difficult to diagnose.There may be a genetic predisposition in such disease.Early diagnosis and immunotherapy can low the relapse and improve the prognosis.

Objective:To identify strain-specific features of Klebsiella pneumoniae by analyzing metagenomics next generation sequencing (mNGS) data, thereby expanding the downstream applications of mNGS. Methods:The sequences of K.pneumoniae strains were organized from both the self-built database of the long-term multi-center research cohort in China established by the Peking University People′s Hospital from 2009 to 2020 (with 2 345 sequences) and the public databases (with 19 648 sequences). The existing large-scale databases were compressed, and a set of strains representative of clonal groups were screened. A strain genome information library was constructed based on k-mer features, and the most matching representative sequences in the database were searched for the raw mNGS data. The search results of the self-built library and public library were merged and optimized to update the prediction of antimicrobial-resistance characteristics and avoid the impact of uneven data distribution on the results. A total of 314 clinical samples from patients with K.pneumoniae detected by mNGS in the Clinical Microbiology Laboratory of Peking University People′s Hospital from 2022 to 2024 were retrospectively collected, and 101 samples with positive clinical culture results were selected to validate the prediction results. The antimicrobial-resistance phenotypes were verified by clinical antimicrobial susceptibility test results. Whole-genome sequencing was performed on the culture strains of 14 samples randomly selected using random numbers to verify the genotypes. Single nucleotide polymorphism distance analysis was used to verify the occurrence of outbreak events. The χ2 test and Mann-Whitney U test were used for statistical analysis. Results:A representative strain sequence k-mer feature library containing self-built and public sub-libraries was constructed. The library construction required only about 1 hour with <3 GB storage, with a high compression ratio and low update cost. Using k-mer-based analysis, mNGS data achieved precise strain characterization within 4 minutes and and <5 GB memory occupation. There was a significant difference in the antimicrobial-resistance rates to more than half of the antibiotics between the self-built database (90.8%, 2 130/2 345) and the public database (22.7%, 4 457/19 648) ( χ2=4 634.1, P<0.001). After optimizing the search results, the mean category agreement, sensitivity, and specificity of the prediction for eight antibiotics reached 84.8% (323/381), 78.9% (131/166), and 91.2% (196/215), respectively. The target genotypes were successfully detected in 10 out of 12 samples, and two outbreak events (2 samples per event) were successfully identified. Conclusions:An independent analysis process adapted to the needs of identifying the features of K. pneumoniae strains in mNGS data was developed. This process requires minimal computational resources and processing time and can directly achieve the simultaneous analysis of the antimicrobial-resistance phenotypes of K. pneumoniae at the strain level and their corresponding genomic characteristic profiles based on the raw mNGS reads.

Viral infection can induce endoplasmic reticulum stress(ERS)and unfolded protein re-sponse(UPR)in host cells,resulting in perturbation of endoplasmic reticulum homeostasis.To e-lucidate the action mechanism of isochlorogenic acid A(IAA)in regulating peste des petits rumi-nant virus(PPRV)-induced ERS and UPR,MTT assay,indirect immunofluorescence assay and Western blot were used to evaluate the anti-PPRV activity of IAA,and the effects of IAA on PPRV-induced ERS and PERK signaling pathway were studied by Western blot and quantitative real-time PCR.The results showed that the PPRV replication and virus-induced cytopathic in LDG-2 cells were significantly inhibited,and the survival rate of virus-infected cells was significantly in-creased due to IAA treatment.Compared with the virus control group,the expression levels of GRP78 and p-eIF2α,the ratios of p-PERK/PERK and p-eIF2α/eIF2α in IAA treated PPRV-infec-ted cells were significantly decreased.The expression level of GADD153 significantly decreased at 24,36 h,and significantly increased at 48,60 h.Furthermore,treatment with ERS inhibitor 4-PBA could significantly suppress the expression levels of GRP78,PPRV-N protein and GADD153 in PPRV-infected cells,and the ratios of p-eIF2α/eIF2α and p-PERK/PERK in PPRV-infected cells were also significantly decreased caused by treatment with IAA or 4-PBA and IAA combination.These findings implicated that the PPRV-induced ERS could be alleviated by inhibiting activation of the PERK-eIF2α-GADD1 53 signaling pathway,which led to restriction of PPRV replication in host cells.

Viral infection can induce endoplasmic reticulum stress(ERS)and unfolded protein reac-tion(UPR)in host cells.This study aims to further explore the effects of ERS induced by pest des petits ruminants virus(PPRV)infection on UPR signaling pathway,virus replication and apopto-sis of host cells.MTT assay,indirect immunofluorescence assay(IFA)and Western blot were used to observe the proliferation of PPRV in goat kidney cells(LDG-2).Western blot and real-time flu-orescence quantitative PCR(qRT-PCR)were used to observe the effects of PPRV infection on the expression levels of GRP78,PERK and its downstream signal molecules,apoptosis-related proteins Bcl-2 and Bax.The result indicated that the cell survival rate was significantly declined with evident cytopathic effect at 36 h post-infection,and the expression level of PPRV-N protein tended to be elevated,and was significantly higher than that of cell control at 30 h post-infection.Meanwhile,the expression levels of GRP78,p-eIF2α and GADD153,the ratio of p-PERK/PERK and p-eIF2α/eIF2α were significantly increased.Moreover,the expression levels of PPRV-N protein,GRP78,p-eIF2α and GADD1 53,the ratio of p-eIF2α/eIF2α and p-PERK/PERK were significantly decreased in PPRV-infected cells due to 4-PBA treatment.The expression level of apoptosis-related Bcl-2 was down-regulated,Bax was up-regulated,and the ratio of Bcl-2/Bax was significantly decreased.Therefore,the activation of PERK/eIF2α/GADD153 signaling pathway could be induced by PPRV infection resulting in alleviating of virus-induced ERS,which is beneficial to viral replication.Bloc-king PPRV-induced ERS could inhibit the activation of PERK signaling pathway and virus replica-tion.PPRV infection and prolonged ERS can induce apoptosis of LDG-2 cells.

MTT assay,indirect immunofluorescence assay(IFA)and real-time fluorescence quanti-tative PCR(qRT-PCR)were used to observe the proliferation of PPRV in goat kidney cells(LDG-2).Western blot and qRT-PCR were used to evaluate the effects of PPRV infection on the expres-sion levels of TLR2,MyD88,NF-κB signaling pathway-related factors and their downstream in-flammatory factors.The results indicated that the significantly decreased cell survival rate and ob-vious cytopathic effect were observed at 36 h post PPRV infection,and the mRNA expression level of PPRV-N gene was significantly up-regulated.At the same time,the expression levels of TLR2,MyD88,p-p65 and p-IκBα,the ratio of p-p65/p65 and p-IκBα/IκBα and the mRNA expression levels of downstream inflammatory factors TNFα,IL-1β,IL-4 and IL-10 were significantly increased.Mo-reover,the expression levels of PPRV-N mRNA,TLR2,MyD88,p-p65 and p-IκBα,the ratio of p-p65/p65 and p-IκBα/IκBα and the mRNA expression levels of downstream inflammatory factors IL-1β and IL-4 in PPRV-infected cells were significantly decreased in the presence of the inhibitor C29 of TLR2.These findings implied that the TLR2/MyD88/NF-κBα signaling pathway can be activated by PPRV infection,which is beneficial to the replication and spread of the virus.Blocking down the activation of TLR2 can inhibit MyD88/NF-κB signaling pathway and viral replication in PPRV-infected cells.

Objective:To analyze the gene sequence of varicella-zoster virus (VZV) in Liaoning Province, and determine the prevailing dominant genotypes and nucleotide and amino acid variations.Methods:The open reading frames (ORFs) of 31 VZV strains from 2017 to 2020 in Liaoning Province were analyzed by PCR, including 1, 6, 12, 16, 17, 21, 22, 35, 37, 38, 50, 54, 55, 56, 60 and 66. The amplified products were sequenced, combined with single nucleotide polymorphism (SNP) and phylogenetic tree to determine the virus genotype, and the variation of nucleotides and amino acids at different sites was analyzed.Results:All 31 VZV strains in Liaoning Province were Clade 2 genotype. Compared with Clade 2 genotype reference strains, the 31 strains had nucleotide and amino acid homology of 99.6%-100.0% and 98.7%-100.0%, respectively, and the genetic distance was 0-0.002. Compared with V-Oka vaccine strain, the 31 strains all had site mutation, which led to amino acid changes, including one strain with ACCTCCCAA deletion at 541-549 sites of ORF1 and two strains with inserted CGG at the 780-781 site of ORF1; the 31 VZV strains had point mutations at 24 sites, including 15 synonymous mutations, 9 missense mutations, 20 mutations in the coding region, 4 mutations outside the coding region, 13 synonymous mutations in the coding region and 7 missense mutations in the coding region. The missense mutations in the coding region included a base mutation of C→T at site 731, a base mutation of C→T at site 790, a base mutation of C→T at site 791, a base mutation of A→G at site 17829, a base mutation of G→A at site 24567, a base mutation of T→C at site 98261, a base mutation of A→C at site 101579, which leaded to the amino acid changes of Arginine→Lysine, Arginine→Glutamine, Arginine→Glutamine, Histidine→Arginine, Arginine→Glutamine, Tyrosine→Histidine, Leucine→Arginine.Conclusions:Clade 2 genotype is the dominant genotype of VZV in Liaoning Province in recent years, and the gene sequences of VZV strains in Liaoning Province is highly conserved. Studying the characteristics of VZV gene is of great significance for studying the molecular epidemiology of VZV in Liaoning Province, and provides important scientific basis for varicella control and vaccination plan.

Objective:To analyze the gene sequence of varicella-zoster virus (VZV) in Liaoning Province, and determine the prevailing dominant genotypes and nucleotide and amino acid variations.Methods:The open reading frames (ORFs) of 31 VZV strains from 2017 to 2020 in Liaoning Province were analyzed by PCR, including 1, 6, 12, 16, 17, 21, 22, 35, 37, 38, 50, 54, 55, 56, 60 and 66. The amplified products were sequenced, combined with single nucleotide polymorphism (SNP) and phylogenetic tree to determine the virus genotype, and the variation of nucleotides and amino acids at different sites was analyzed.Results:All 31 VZV strains in Liaoning Province were Clade 2 genotype. Compared with Clade 2 genotype reference strains, the 31 strains had nucleotide and amino acid homology of 99.6%-100.0% and 98.7%-100.0%, respectively, and the genetic distance was 0-0.002. Compared with V-Oka vaccine strain, the 31 strains all had site mutation, which led to amino acid changes, including one strain with ACCTCCCAA deletion at 541-549 sites of ORF1 and two strains with inserted CGG at the 780-781 site of ORF1; the 31 VZV strains had point mutations at 24 sites, including 15 synonymous mutations, 9 missense mutations, 20 mutations in the coding region, 4 mutations outside the coding region, 13 synonymous mutations in the coding region and 7 missense mutations in the coding region. The missense mutations in the coding region included a base mutation of C→T at site 731, a base mutation of C→T at site 790, a base mutation of C→T at site 791, a base mutation of A→G at site 17829, a base mutation of G→A at site 24567, a base mutation of T→C at site 98261, a base mutation of A→C at site 101579, which leaded to the amino acid changes of Arginine→Lysine, Arginine→Glutamine, Arginine→Glutamine, Histidine→Arginine, Arginine→Glutamine, Tyrosine→Histidine, Leucine→Arginine.Conclusions:Clade 2 genotype is the dominant genotype of VZV in Liaoning Province in recent years, and the gene sequences of VZV strains in Liaoning Province is highly conserved. Studying the characteristics of VZV gene is of great significance for studying the molecular epidemiology of VZV in Liaoning Province, and provides important scientific basis for varicella control and vaccination plan.