Objective: To investigate the prevalence of Dengue virus (DENV) infection among voluntary blood donors in Xishuangbanna Dai Autonomous Prefecture, and to evaluate the necessity of implementing nucleic acid testing (NAT) for blood donors during the rainy season (May-October). Methods: Prior to initiating donor screening, the Xishuangbanna Central Blood Center conducted in-house validation of reagent performance and participated in external quality assessment (EQA) organized by the National Center for Clinical Laboratories (NCCL). During the surveillance period (August-October 2024), a total of 2 919 donor samples were screened using a 6-sample mini-pool NAT strategy. Daily internal quality controls were recorded. Samples that tested positive in pooled screening were deconvoluted and retested in duplicate; only those reactive in both replicate wells were sent to the NCCL for confirmatory testing. At NCCL, samples underwent re-testing using five domestic NAT reagents, as well as serological assays for NS1 antigen and DENV-specific IgG/IgM. Confirmed positive samples were further characterized by serotyping, envelope (E) gene sequencing, and phylogenetic analysis using the maximum likelihood method. Results: The DENV NAT reagent demonstrated consistent detection of 40 copies/mL controls in individual donor (ID)-NAT test (mean CT: 35.61±0.40). During the 63-day quality control monitoring, DENV detection remained stable (mean CT: 22.53±0.72). The center achieved full marks in EQA assessments for 2023 and 2024. Three reactive pools were identified in initial screening, and subsequent individual testing confirmed three DENV RNA-positive donors (sample numbers: 2401, 2402, and 2403). The confirmatory test results from NCCL were: all five NAT platforms consistently detected DENV RNA in the three samples; for serological tests, 2 samples (2402, 2403) were positive for NS1 antigen, while all three samples were negative for both IgG and IgM antibodies. DENV serotyping reagents identified DENV-2 in all cases, which were further confirmed as DENV-2 Genotype Ⅱ-Cosmopolitan by E gene sequencing. Phylogenetic analysis indicated that samples 2401 and 2402 clustered with Southeast Asian strains (Thailand/MZ636802.1, Laos/PQ775621.1), while sample 2403 closely matched a previously reported local Yunnan strain (PV544686.1). Conclusion: DENV-2 infection was detected among blood donors in Xishuangbanna during the rainy season, indicating concurrent risks of imported and local transmission. We recommend implementing pooled NAT screening for blood donors in high-risk areas during dengue epidemic seasons, along with strengthened laboratory quality control, to enhance blood safety.

Objective To screen a Madin-Darby canine kidney (MDCK) cell line for H5N1 influ-enza virus isolation and to evaluate its safety in vaccine production. Methods MDCK cells were cloned by the method of limiting dilution. Hemagglutination test was used to screen MDCK cells that were suitable for H5N1 influenza virus production. Tests for analyzing the characteristics, extraneous agents, endogenous agents and tumorigenicity of MDCK cells were performed according to Chinese Pharmacopeia Volume Ⅲ. Results A total of 108 MDCK cell lines were obtained and three of them were selected after hemagglutina-tion test. G1 cells were chosen following further screening with tumorigenicity test and receptor abundance analysis. The average number of chromosomes of the MDCK-G1 cells was 78±4. No bacteria, fungi or myco-plasma contamination was detected. In experimental group, each nude mouse was injected with 1×107/ml viable cells to observe their tumorigenicity. Twelve weeks after cell injection, no node was found at injection sites or in gross anatomy. There was no significant difference between the experimental and negative control groups. The result of the tumorigenicity test was negative. No node formation was found after injecting nude mice with cell lysate or cellular DNA collected from equivalent amount of cells. It was indicated that the MDCK-G1 cells were of low-oncogenic potential. Conclusions The MDCK-G1 cell line could be used as a substrate to produce H5N1 influenza virus vaccine.

Objective We aimed to use 1H-MRS to characterize metabolite concentrations in the bilateral hippo?campus in GPI patient. Methods Metabolite ratios in the bilateral hippocampus were compared between patients with GPI (n=52) and Normal Control (NC) (n=38). Clinical neurological tests were measured in all subjects and were correlat?ed to the metabolite concentrations. Results The GPI patients showed significantly lower concentrations of N-acetylas?partate(NAA)/creatine(Cr) ratios in the bilateral hippocampus region compared to the NC subjects. There was significant?ly difference in the NAA/Cr ratios between the mild GPI dementia and the severe GPI dementia groups on the left hippo?campus region. We found that the NAA/Cr ratios concentrations were positively correlated with Mini Mental state Exami?nation (MMSE) and Montreal Cognitive Assessment scale (MoCA) scores in the left hippocampus region and the mI/Cr ra?tios concentrations were positively correlated. Conclusions GPI Patients have neuronal dysfunction in the bilateral hippo?campus. The severity of cognitive impairments is associated with the severity of the damage in the left side.

Objective To explore the plasma levels of soluble CD40 (sCD40) and soluble CD40 ligand (sCD40L) in the patients with Alzheimer’s disease (AD) and those with amnestic mild cognitive impairment (aMCI). Methods The levels of plasma sCD40 and sCD40L were measured in 20 patients with AD, 35 patients with aMCI, and 32 cognitively normal controls (NC) using commercially available ELISAs. The cognitive function of AD and aMCI patients was mea?sured by mini-mental state examination (MMSE). Results There were significant differences in plasma sCD40 among AD, aMCI and NC groups (P<0.05) as the medians (the upper and lower quartiles) of plasma levels were 123.3 (97.4, 149.5) pg/mL, 102.9 (63.6, 124.0) pg/mL and 70.66 (51.0, 90.8) pg/mL, respectively. There were significant differences in plasma sCD40L among AD, aMCI and NC groups (P<0.05) as plasma levels were 537.0 (316.0, 1134.0) pg/mL, 316.0 (190.0,546.0) pg/mL and 167.0 (107.5,478.0) pg/mL. A negative correlation between the plasma concentrations of sCD40L and the MMSE scores was found in aMCI patients (r=-0.736, P<0.001). Conclusions There are relevant chang?es of plasma sCD40 and sCD40L levels in patients with AD and aMCI. The present results suggest that plasma levels of sCD40 and sCD40L may be appropriate biomarkers for AD patients and indicate that CD40-CD40L signaling may be in?volved in AD pathophysiology.