Duration of SARS-CoV-2 RNA shedding and factors associated with prolonged viral shedding in patients with COVID-19.

To investigate the factors associated with the duration of severe acute respiratory syndrome coronavirus 2 RNA shedding in patients with coronavirus disease 2019 (COVID-19). A retrospective cohort of COVID-19 patients admitted to a designated hospital in Beijing was analyzed to study the factors affecting the duration of viral shedding. The median duration of viral shedding was 11 days (IQR, 8-14.3 days) as measured from illness onset. Univariate regression analysis showed that disease severity, corticosteroid therapy, fever (temperature>38.5°C), and time from onset to hospitalization were associated with prolonged duration of viral shedding (P < .05). Multivariate regression analysis showed that fever (temperature>38.5°C) (OR, 5.1, 95%CI: 1.5-18.1), corticosteroid therapy (OR, 6.3, 95%CI: 1.5-27.8), and time from onset to hospitalization (OR, 1.8, 95%CI: 1.19-2.7) were associated with increased odds of prolonged duration of viral shedding. Corticosteroid treatment, fever (temperature>38.5°C), and longer time from onset to hospitalization were associated with prolonged viral shedding in COVID-19 patients.

Pathological Findings in Myasthenia Gravis Patients with Thymic Hyperplasia and Thymoma.

Thymectomy is routinely carried out in patients with myasthenia gravis (MG) and thymomas. However, there is still a dispute as to whether MG patients with thymic hyperplasia should undergo thymectomy. We aimed to investigate the pathological findings in the thymus in patients with co-existing MG and thymic hyperplasia or thymomas treated with thymectomy, as well as effects of immunosuppression. Thirty-three patients with MG were selected and grouped accordingly: patients with no thymic abnormalities, patients with thymic hyperplasia, and patients with thymomas. All patients were treated with methylprednisolone alongside immunosuppression. A separate cohort of 24 MG patients with thymic hyperplasia or thymomas and treated with thymectomy were selected. As controls, 5 patients with thymomas or thymic carcinoma without MG were selected. Expression of CD5, extracellular regulated protein kinases1/2 mitogen activated protein kinase (ERK1/2MAPKs) and CD95 ligand (FasL) in the thymus was examined. Methylprednisolone and immunosuppressive therapy are highly effective in MG patients with normal thymus tissue and MG patients with thymic hyperplasia compared to MG patients with thymomas alone. CD5 expression was highest in MG patients with thymic hyperplasia, correlating with expression of ERK1/2MAPKs. FasL expression was similar across all groups. Thymomas may be distinguished from thymic hyperplasia by expression of CD5 and ERK1/2MAPKs. Thymectomy is the preferred treatment for MG patients with thymomas but may not be necessary in MG patients with thymic hyperplasia who are treated with immunosuppressive therapy.

Hippocampal immediate early gene transcription in the rat fluid percussion traumatic brain injury model.

Traumatic brain injury (TBI) is one of the leading causes of neurological disability and death in the USA across all age groups, ethnicities, and incomes. In addition to the short-term morbidity and mortality, TBI leads to epilepsy and severe neurocognitive symptoms, both of which are referenced to post-traumatic hippocampal dysfunction, although the mechanisms of such hippocampal dysfunction are incompletely understood. Here, we study the temporal profile of the transcription of three select immediate early gene (IEG) markers of neuronal hyperactivation, plasticity, and injury, c-fos, brain-derived neurotrophic factor (BDNF), and Bax, in the acute period following the epileptogenic lateral fluid percussion injury in a rodent TBI model. We found that lateral fluid percussion injury leads to enhanced expression of the selected IEGs within 24 h of TBI. Specifically, BDNF and c-fos increase maximally 1-6 h after TBI in the ipsilesional hippocampus, whereas Bax increases in the hippocampus bilaterally in this time window. Antagonism of the N-methyl-D-aspartate-type glutamate receptor by MK801 attenuates the increase in BDNF and Bax, which underscores a therapeutic role for N-methyl-D-aspartate-type glutamate receptor antagonism in the acute post-traumatic time period and suggests a value to a hippocampal IEG readout as an outcome after injury or acute therapeutic intervention.

Expression of L protein of Hantaan virus 84FLi strain and its application for recovery of minigenomes.

Hantaan virus (HTNV) is an Old World hantavirus associated with hemorrhagic fever with renal syndrome (HFRS). To visualize the localization of the L protein of HTNV strain 84FLi within cells, a fusion protein composed of enhanced green fluorescent protein and L protein, EGFP-L, was expressed in Vero cells. The 273 KDa expressed fusion protein of EGFP-L localized in the perinuclear region. We also described the development of a reverse genetics system for HTNV strain 84FLi. The RNA polymerase I (pol I)-mediated transcription system was used to generate artificial viral RNA genome segments (minigenomes), which contained the chloramphenicol acetyltransferase (CAT) reporter gene in antisense (virus RNA) or sense (virus-complementary RNA) orientation flanked by the noncoding regions of HTNV 84FLi L segment. CAT could be detected in cells after transfection, indicating the successful encapsidation, transcription and replication of the pol I-derived minigenomes. The passaged transfer of CAT demonstrates that recombinant virus containing packaged pol I-derived minigenomes has been produced. This system may be helpful in studying the gene function and pathogenesis of HTNV.

[Identification of a functional ITAM-like sequence within G1 cytoplasmic tail of Hantaan virus].

The G1 cytoplasmic tail of Hantaan virus (HTNV) harbors a highly conserved region, which is homologous to immunoreceptor tyrosine-based activation motifs (ITAM) and is termed the ITAM-like sequence. To demonstrate the potential signal-transducing activity of G1 ITAM-like sequence resembling the canonical ITAM within immune and endothelial cells, a series of experiments were performed to define its interaction with cellular kinases. The synthesized G1 ITAM-like peptide was shown to coprecipitate with cellular phosphoprotein complexes by an immune-complex kinase assay. Mutational analyses showed that this ITAM-like sequence was a substrate for the Src family kinase Fyn, and two conserved tyrosine residues were required for coprecipitating Lyn, Syk, and ZAP-70 kinases. These findings demonstrated that HTNV envelope glycoprotein G1 contains a functional ITAM-like sequence in its cytoplasmic tail, which can bind critical cellular kinases that regulate immune and endothelial cell functions.

Aberrant activation of CDK5 is involved in the pathogenesis of OPIDN.

Exposure to triorthocresyl phosphate (TOCP) may result in a late neurological complication, i.e. organophosphate-induced delayed neuropathy (OPIDN). The aim of this study was to examine changes in levels of cyclin-dependent kinase 5 (CDK5) and of its activator, p35/p25, in the spinal cord of hens treated by TOCP. After exposure to a single dose of TOCP, groups of adult hens were examined in 3, 5, 7, 9, 14, and 18 days after exposure. CDK5, p35/p25 expression and distribution in the lumbar spinal cord were evaluated by immunohistochemistry and Western blotting. The hens showed signs of OPIDN around day 9 after exposure. The number of p (phosphorylated) -CDK5 and p35 positive cells increased significantly. Co-localization and mislocalization of p-CDK5 and p35/p25 was identified and became evident in neurons around the 9th day. Meanwhile, CDK5, p-CDK5, p35, p25 protein levels and p25/p35 ratio were increased, and peaked around the 9th day, then decreased. Some hens' unilateral common peroneal was treated by roscovitine 3 days after TOCP exposure. Axonal transport of these nerves was faster than of their opposite side and of those simply treated by TOCP. These findings indicate aberrant activation of CDK5 may be involved in the pathogenesis of OPIDN.

Expression of dendritic cell-specific intercellular adhesion molecule 3 grabbing nonintegrin on dendritic cells generated from human peripheral blood monocytes.

AIM: To generate dendritic cells (DCs) from human peripheral blood and to detect the expression of dendritic cell-specific intercellular adhesion molecule 3 grabbing nonintegrin (DC-SIGN; CD209) for the further study of DC-SIGN in hepatitis C virus (HCV) transmission. METHODS: Peripheral blood monocytes were isolated from blood of healthy individuals by Ficoll-Hypaque sedimentation and cultured in complete medium containing rhGM-CSF and rhIL-4. Cells were cultured for seven days, with cytokine addition every two days to obtain immature DCs. Characteristics of the cultured cells were observed under light and scanning microscope, and the expression of DC-SIGN was detected by immunofluorescence staining. RESULTS: After seven-day culture, a large number of cells with typical characteristics of DCs appeared. Their characteristics were observed under light and scanning electron microscope. These cells had a variety of cell shapes such as those of bipolar elongate cells, elaborate stellate cells and DCs. DC-SIGN was detected by immunofluorescence staining and its expression level on cultivated dendritic cells was high. CONCLUSION: DCs with a high expression of DC-SIGN can be generated from human peripheral blood monocytes in complete medium containing rhGM-CSF and rhIL-4.

Cellular entry of Hantaan virus A9 strain: specific interactions with beta3 integrins and a novel 70kDa protein.

Cellular entry of pathogenic hantaviruses had been shown to be mediated by beta3 integrins. However, no direct evidence exists that hantavirus binds to beta3 integrins, and integrin beta3 subunit is not expressed on some cells permissive to hantavirus infection. In this report, utilizing beta3-integrin-transfected CHO cells, we demonstrated that integrin beta3 subunit renders CHO cells susceptible to Chinese Hantaan virus (HTN) strain A9 (isolated in China), and the viral infection was correspondingly inhibited by antibodies to alphavbeta3, alphaIIbbeta3, beta3, and alphav integrins. Furthermore, virus overlay protein-binding assay and 'quarternary Western' analysis indicate that HTN A9 directly interacts with beta3 integrins and an unidentified 70kDa protein. These findings indicate that beta3 integrins play a crucial role in cellular entry of HTN A9 via specific interactions with the virus. In addition, a novel 70kDa protein may serves as a candidate receptor or alternative cellular component for interaction with HTN.

[Exosome: Trojan horse in immunotherapy].

Exosomes are small membrane-bound vesicles that are secreted by a multitude of eukaryocytes as a consequence of fusion of multivesicular bodies with the plasma membrane. Exosomes can play critical roles in different physiological processes depending on their origins. Exosomes secreted from professional antigen-presenting cells are enriched in MHC class I and II complexes, costimulatory molecules, hsp 70 and hsp 90 chaperones, therefore exosomes, like Trojan horse, are of importance of immunoregulation in vivo and in vitro. The review will present current trends of research on the fundamental properties, production and purification of exosomes, and will focus on their implementation in cancer and virus immunotherapy as a novel cell-free peptide-based vaccine.

[Spinal cord neuronal apoptosis induced by triorthocresyl phosphate poisoning in hens].

OBJECTIVE: To investigate the role of neuronal apoptosis in organophosphorus poisoning-induced delayed neuropathy (OPIDN) and its dynamic pathological changes. METHODS: To establish OPIDN animal model, triorthocresyl phosphate (TOCP)was given to hens with a single dose (1 000 mg/kg, im). Changes of neuropathology, number of neurons and apoptotic cells in the third lumbar spinal cord were observed by HE, Nissl and TUNEL methods 3, 5, 7, 10, 14, 18 days after injection. RESULTS: The hens showed OPIDN typical signs (progressive ataxia and hypotonia) about 9 days after TOCP exposure. HE staining revealed dark red nucleus in neurons of anterior horn of lumbar spinal cord 5 days after exposure, but this phenomenon disappeared 18 days later. Nissl method showed that the number of neurons in anterior horn of spinal cord decreased [from (82 +/- 4) cell/mm(2) to (66 +/- 6) cell/mm(2)]. TUNEL positive cells began to appear [(22 +/- 2) cell/mm(2)] 5 days after TOCP exposure, and reached the peak [(27 +/- 3) cell/mm(2)] 7 days later, and disappeared 18 days later. CONCLUSION: Neuronal apoptosis in anterior horn of spinal cord of hens appeared in OPIDN, suggesting that cellular apoptosis may play an important role in the pathogenesis of OPIDN.

[The relationship between cellular infection by Hantaan virus and expression of beta3 integrin].

OBJECTIVE: To investigate the relationship between cellular entry of Hantaan virus (HTNV) and expression of beta3 integrin in beta3-integrin-deficient and HTNV-insusceptible China hamster ovary (CHO) cells. METHODS: Eukaryotic expression vector encoding human integrin beta3 and eukaryotic expression vector harboring human integrin alphav or alphaIIb subunit cDNA were transfected into HTNV non-permissive CHO cells individually or collectively. Screening for stable transfectant clones was performed using G418 selective (culture medium. The exogenous gene expression was analyzed qualitatively and quantitatively by immunofluorescence assay (IFA) and flow cytometry (FCM). Various modified CHO cells and untransfected CHO cells were infected using HTNV A9. At various time points after infection, HTNV antigens in infected cells were detected qualitatively and quantitatively by IFA, FCM. RESULTS: Highly-effective surface expression of beta3 integrin was measured in CHO/alphavbeta3 and CHO/alphaIIbbeta3, while weaker surface expression was detected in CHO/beta3 (P < 0.05). Expression of alphav or alphaIIb integrin in the individually transfected group was significantly lower than in the cotransfected group (P < 0.01) and the sites of localization changed. In contrast, effective surface expression was not seen when pcDNA3 was transfected alone. The infection rate of CHO/alphavbeta3 (60.1%) and CHO/alphaIIbbeta3 (55. 9%) cells were significantly higher than that of CHO/beta3 (38.7%) cells, while the infection rate of CHO/beta3 was significantly higher than that of CHO/alphav, CHO/pcDNA3 and CHO cells respectively. There was a close relationship between the positive percentage of HTNV A9-infected cells and expression of beta3 integrin. CONCLUSION: These results indicated that cellular entry of HTNV was related to the expression of beta3 integrin.

[Construction of human integrin beta3 subunit eukaryotic expression vector and efficient surface expression of integrin alphaIIbbeta3].

AIM: To establish efficient surface expression of Homo sapiens integrin alphaIIbbeta3 in beta3-integrin-deficient and HV-insusceptible CHO cells, so as to lay the foundation for the further study of cellular entry of hantavirus mediated by beta3 integrins. METHODS: Eukaryotic expression vector pcDNA3.1-beta3 harboring ORF region of human integrin beta3 subunit cDNA was constructed, then pcDNA3.1-beta3 and eukaryotic expression vector pBJ1-alphaIIb containing human integrin alphaIIb subunit cDNA were transfected into CHO cells alone or together. The expression of exogenous genes were analyzed by indirect immunofluorescence assay (IFA). RESULTS: The eukaryotic expression vector pcDNA3.1-beta3 was constructed successfully. IFA examination showed that surface expression of integrin alphaIIb beta3 was highly effective in cotransfection group, while surface expression was weak on CHO cells transfected with pcDNA3.1-beta3 alone,and no effective surface expression was found in pBJ1-alphaIIb-transfected group. CONCLUSION: Efficient surface expression of integrin alphaIIb beta3 requires expression of both subunits.