The Viral Load of Epstein-Barr Virus in Blood of Children after Hematopoietic Stem Cell Transplantation.

Objective: To detect the Epstein-Barr virus (EBV) viral load of children after hematopoietic stem cell transplantation (HSCT) using chip digital PCR (cdPCR). Methods: The sensitivity of cdPCR was determined using EBV plasmids and the EBV B95-8 strain. The specificity of EBV cdPCR was evaluated using the EBV B95-8 strain and other herpesviruses (herpes simplex virus 1, herpes simplex virus 2, varicella zoster virus, human cytomegalovirus, human herpesvirus 6, and human herpesvirus 7). From May 2019 to September 2020, 64 serum samples of children following HSCT were collected. EBV infection and the viral load of serum samples were detected by cdPCR. The epidemiological characteristics of EBV infections were analyzed in HSCT patients. Results: The limit of detection of EBV cdPCR was 110 copies/mL, and the limit of detection of EBV quantitative PCR was 327 copies/mL for the pUC57-BALF5 plasmid. The result of EBV cdPCR was up to 121 copies/mL in the EBV B95-8 strain, and both were more sensitive than that of quantitative PCR. Using cdPCR, the incidence of EBV infection was 18.75% in 64 children after HSCT. The minimum EBV viral load was 140 copies/mL, and the maximum viral load was 3,209 copies/mL using cdPCR. The average hospital stay of children with EBV infection (184 ± 91 days) was longer than that of children without EBV infection (125 ± 79 days), P = 0.026. Conclusion: EBV cdPCR had good sensitivity and specificity. The incidence of EBV infection was 18.75% in 64 children after HSCT from May 2019 to September 2020. EBV cdPCR could therefore be a novel method to detect EBV viral load in children after HSCT.

Interaction between 14-3-3ß and PrP influences the dimerization of 14-3-3 and fibrillization of PrP106-126.

Proteins of the 14-3-3 family are universal participate in multiple cellular processes. However, their exact role in the pathogenesis of prion diseases remains unclear. In this study, we proposed that human PrP was able to form molecular complex with 14-3-3ß. The domains responsible for the interactions between PrP and 14-3-3ß were mapped at the segments of amino acid (aa) residues 106-126 within PrP and aa 1-38 within 14-3-3ß. Homology modeling revealed that the key aa residues for molecular interaction were D22 and D23 in 14-3-3ß as well as K110 in PrP. Mutations in these aa residues inhibited the interaction between the two proteins in vitro. Our results also showed that recombinant PrP encouraged 14-3-3ß dimer formation, whereas PrP106-126 peptide inhibited it. Recombinant 14-3-3ß disaggregated the mature PrP106-126 fibrils in vitro. Moreover, the PrP-14-3-3 protein complexes were observed in the brain tissues of normal and scrapie agent 263K infected hamsters. Colocalization of PrP and 14-3-3 was seen in the cytoplasm of human neuroblastoma cell line SH-SY5Y, as well as human cervical cancer cell line HeLa transiently expressing full-length human PrP. Our current data suggest the neuroprotection of PrPC and neuron damage caused by PrPSc may be associated with their functions of 14-3-3 dimerization regulation.

The prepared tau exon-specific antibodies revealed distinct profiles of tau in CSF of the patients with Creutzfeldt-Jakob disease.

BACKGROUND: The diagnostic value of CSF tau for Creutzfeldt-Jakob disease (CJD) has been widely evaluated, showing a markedly disease-relative manner. However, the profiles of tau isoforms in CSF of CJD patients remain unknown. Here, we prepared the exon-specific antibodies against the peptides encoded by exon-2, exon-3 and exon-10 of human tau protein and evaluated the reactive profiles of tau in CSF samples from the patients with probable CJD. METHODOLOGY/PRINCIPAL FINDINGS: Sequences encoding exon-2, exon-3 and exon-10 of human tau protein were cloned into a prokaryotic expression vector pGEX-2T. Using recombinant fusion proteins GST-E2, GST-E3 and GST-E10, three tau exon-specific antibodies were elicited. Reliable specificities of the prepared antibodies were obtained after a serial of purification processes, not only in recognizing the tau peptides encoded by exon-2, -3 and -10, but also in distinguishing six recombinant tau isoforms by Western blot and ELISA. Three predominant tau-specific bands were observed in CSF samples with the exon-specific and the commercial tau antibodies, respectively, showing different reactive profiles between the groups of probable CJD and non-CJD. A 65 KD band was detected only in the CSF samples from probable CJD patients, especially with the antibodies against exon-2 (Anti-tE2) and exon-10 (Anit-tE10). The appearances of 65 KD band in CSF correlated well with positive 14-3-3 in CSF and typical abnormality in EEG. Such band was not observed in the CSF samples of six tested genetic CJD patients. CONCLUSIONS/SIGNIFICANCE: Three exon-specific polyclonal antibodies were successfully prepared. Based on these antibodies, different CSF tau profiles in Western blots were observed between the groups of probable CJD and non-CJD. A disease-specific tau band emerged in the CSF samples from probable sporadic CJD, which may supply a new biomarker for screening sporadic CJD.

Manganese-induced changes of the biochemical characteristics of the recombinant wild-type and mutant PrPs.

Manganese may play some roles in the pathogenesis of prion diseases. In this study, recombinant human wild-type (WT) PrP and PrP mutants with deleted or inserted octarepeats were exposed to manganese, and their biochemical and biophysical characteristics were evaluated by proteinase K (PK) digestion, sedimentation experiments, transmission electron microscopy and circular dichroism. It demonstrated that incubation of manganese remarkably increased PK-resistances, protein aggregations and beta-sheet contents of the PrPs. Moreover, the PrP mutants of inserted or deleted octarepeats were much vulnerable to the influence of manganese, which showed obviously more aggregation and higher beta-sheet content than that of WT-PrP. It highlights that the effect of manganese on the PrP seems to lie on the incorrectness of the octarepeats numbers. The association of the octarepeats number of PrP with manganese may further provide insight into the unresolved biological function of PrP in the neurons.

[Molecular interaction between PrP protein and the signal protein 14-3-3 beta].

The molecular interaction between PrP and 14-3-3 beta and the possible interactional domain between two proteins were studied by co-immunoprecipitation, pull down and FRET assays. The results showed that PrP protein could interact with 14-3-3 beta in vitro and in vivo. The domain which responded for the interaction was located at C-terminal of PrP (amino acid residues 106 to 126). This study of the interaction between PrP and 14-3-3 protein further provided the insight into the potential role of 14-3-3 in the biological function of PrP and the pathogenesis of prion disease.

[Preparations of the specific antibodies against exon 2 and exon 3 of human tau protein].

OBJECTIVE: To prepare the specific antibodies against exon 2 and exon 3 of human tau protein. METHODS: Sequences encoding exon 2 and exon 3 of human tau protein were amplified from human peripheral blood DNA and cloned into a prokaryotic expression vector pGEX-2T. Fusion proteins GST-E2 and GST-E3 were expressed and purified from E. coli system. The antisera were elicited by immunization of the purified fusion proteins to rabbits and mice. The specific antibodies were purified by Protein G/A and CNBr-activated sepharose 4B coupled with GST protein. The specificity and sensitivity of the purified antibodies were evaluated by Western blotting and ELISA. RESULTS: Recombinant fusion proteins GST-E2 and GST-E3 were expressed and purified from E. coli, which showed Mr. 29 x 10(3). Various antisera were collected from the immunized experimental animals. Reliable immunoreactive specificity and titers of the purified antibodies against exon 2 and exon 3 of human tau protein were confirmed by Western blotting and ELISA after serial purification processes. CONCLUSION: Four specific antibodies against exon 2 and exon 3 of human tau protein have been successfully prepared, which provides basis for analyzing the role of tau in neurodegenerative diseases.

[Study on the phenomenon of splashes and sprays from virology].

OBJECTIVE: To investigate the phenomenon of accidental splashes and sprays from manipulation of recombinant virus material and to measure the approximate spilled distance when recombinant virus material inadvertently dropped in the biosafety laboratory. METHODS: first, two groups owning different experience simulated the course of accidental spills and splashes by recombinant adenovirus (rADV) which expressed green fluorescence protein (GFP), the GFP signal were observed in 96 well cell plate after spills appeared; Second, the routine two heights (75 cm and 110 cm) and capacity (1 ml, 1.5 ml, 4 ml and 8 ml) of virus were chose to simulate the experiment of unexpected dropping. RESULTS: First, the positive quantity of the first group owning 5 years' experience is much less than the second group owning 2 years' work experience, the former was 7 positive wells, the latter was 81 positive when they used the pipette to operation. Second, when the unclosed test tubes (1 ml, 1.5 ml, 4 ml and 8 ml recombinant virus) inadvertently dropped, the largest spill distance was 0.92 m, 1.57 m, 2.63 m and2.68 m respectively. CONCLUSION: The better experience is important to make sure safety when we make infectious material; the contaminated distance increased with the amount of recombinant virus material.

[The construction and identification of the PRNP vectors with ubiquitin or the lysosome-targeting signal].

OBJECTIVE: To evaluate PrP expression characteristic of PRNP nucleic acid vaccine vector with ubiquitin or the lysosome-targeting signal. METHODS: The gene of ubiquitin and lysosome-targeting signal were ligated to PRNP and pcDNA3.1 vector that is, pcDNA3.1-UPrP and pcDNA3.1-PrPL were constructed. The expression characteristics of PrP with two signals were evaluated by Western Blot and the localization was observed by indirect immune fluorescence. RESULTS: The protein expressed by pcDNA3.1-UPrP and pcDNA3.1-PrPL with ubiquitin and lysosome-targeting signal can be recognized by prion-specific antibody. The protein has three glycosylation molecules form as native PrP.PrP with ubiquitin was degraded gradually with time extension,whereas quantity of PrP with lysosome signal reduced in 48 h after transfection. The protein with two location signals can direct fusion proteins to cytoplasm. CONCLUSION: The PRNP vectors with ubiquitin or the lysosome-targeting signal were constructed and expressed in eukaryocyte successfully. There will be one of good foundation on PRNP nucleic acid vaccine.

[Investigating the risk of two model virus in the laboratory].

OBJECTIVE: To study the survival time of recombination rival in environment and inactivation ability of different disinfectant and ultraviolet radiation against virus. METHODS: NC membranes absorbed the recombinant adenovirus (rADV) or herpes simplex virus (rHSV) with green fluorescence protein (GFP) were laid, or immersed in various concentration of different disinfectants such as ethanol, sodium hypochlorite, lysol and geramine and then taked out them every 15 min, or exposed under ultraviolet radiation, then the NC membranes were adsorbed 1 h in cell, 37 degrees C 5% CO2 48 h. The results were observed under the fluorescence microscope. RESULTS: (1) the average survival time of rHSV under environment is less than 60 min, rADV is almost up to 2 h. (2) The infection ability of rHSV and rADV was inactived 15 min by both ethanol (100%, 70% and 50%) and sodium hypochlorite (5%, 2.5% and 1.25%). (3) Two virus can be killed by 0.1% bromogeramine. (4) Both 5% and 2.5% lysol, but rADV can not lost the infection on Vero Cell until 75 min by 1.25% Lysol. (5) The rHSV was inactivated under ultraviolet radiation, but rADV was not. CONCLUSION: The survival time of is different from both envelope rival and the no-envelope viral under nature environment and the inactivate ability of disinfectant also is different between two model virus; Disinfectant should be choose according to virus type.