Season and side-chain length affect the occurrences and behaviors of phthalic acid esters in wastewater treatment plants.

Emerging pollutants (EPs) are prevalent in aquatic environments globally. Researchers strive to understand their occurrence and behavior prior to their release into the environment. In this study, we examined five wastewater treatment plants (WWTPs), collected 50 wastewater samples and 10 sludge samples. We explored the sources and destinations of phthalic acid esters (PAEs) within these WWTPs using mass balance equations. Wastewater treatment diminished the frequency and concentration of PAEs, and decreased the fraction of short-chain PAEs. We confirmed the increased concentration of PAEs post-primary treatment and modified the mass balance equation. Calculations suggest that weaker "the mix" in winter than in summer and stronger sedimentation in winter than in summer resulted in high efficiency of PAEs removal by winter wastewater treatment. The mass flux of biodegradation was influenced by the combination of biodegradation efficiency and the strength of the particular type of PAEs collected, with no seasonal differences. Mass fluxes for sludge sedimentation were mainly influenced by season and were higher in winter than in summer. This study enhances our understanding of emerging pollutants in manual treatment facilities and offers insights for optimizing wastewater treatment methods for water professionals.

Analysis and improvement of human-induced vibration comfort of articulated steel pedestrian bridges.

The effect of different pedestrian densities (0.2, 0.5, 1, 1.5 and 4.6 persons/m2) on a pedestrian bridge is studied, the comfort level is evaluated according to the acceleration peak, and the most sensitive part of the acceleration response employs tuned mass dampers (TMDs) for vibration control. The study shows that the bearing capacity level of the pedestrian bridge with articulated piers meets the standard. Compared with a pier rigid connection system, the structural dynamic characteristics of pier articulation do not change much, and the vertical frequency and peak acceleration in the span are slightly smaller. The comfort evaluation results of the bridge with articulated piers are the same as those of the bridge with a rigid pier. The TMD setting can effectively reduce the human-induced vibration time response, the vibration reduction efficiency can reach 52%, and the comfort level changes from CL2 to CL1 after vibration reduction.

The fate of phthalate acid esters in wastewater treatment plants and their impact on receiving waters.

Phthalates (PAEs) are gaining attention and being researched as an endocrine disruptor as global plastic use surge. There is an urgent need to explore the key factors affecting the removal of PAEs from wastewater and the impact of wastewater effluent on receiving water. Here we investigated the levels and distribution patterns of 16 typical PAEs in surface water and five wastewater treatment plants (WWTPs) along the Dongyang River from Yiwu, China, collecting 42 surface water and 31 wastewater samples. We found that influent PAEs concentration and treatment process were the key factors affecting the degradation efficiency of PAEs in primary and secondary treatment, respectively. In primary treatment, long-chain PAEs were more easily removed (and sometimes less likely to accumulate) than short-chain PAEs, regardless of the influent PAEs concentration (a key factor in primary treatment), while in secondary treatment, short-chain PAEs were easily removed regardless of the treatment process (a factor in secondary treatment). This was not the case for long-chain PAEs, which were only more readily removed in the A/A/O process. In addition, by comparing the significant differences between wastewater and surface water, we found that the total PAEs in the treated effluent were significantly lower than in surface water upstream and in built-up urban areas, indicating that wastewater discharges in the study area did not increase PAEs in the receiving water. Finally, river in the city center and artificial treatment facilities in the study area were identified as requiring priority attention. The results of this study can serve as a model for controlling PAEs in other similar developing cities in China and provide valuable information on the fate of endocrine disruptor from wastewater treatment in China and their impact on surface water.

Comparison of structural characteristics and combustibility analysis about hydrochar and pyrochar.

The structure characteristics and combustibility of pyrochar and hydrochar were compared using scanning electron microscopy, nitrogen adsorption, Fourier transform infrared spectrum, Raman spectrum and thermogravimetry. The random pore model was applied to analyze the combustion process of chars. With the temperature increasing, analysis of physical structure revealed that the pore structure of hydrochar was more developed than that of pyrochar. Meanwhile, the hydrothermal process had an advantage over pyrolysis in terms of removing oxygen-containing functional groups and improving the coal rank, mainly attributed to the existence of subcritical water. In addition, the high determination coefficient of random pore model indicated that the model could accurately obtain the kinetic parameters. The activation energies calculated of hydrochars were higher than that of pyrochars, indicating that carbon in hydrochar had a more structural stability. The pyrochar obtained after 220 °C was less combustible than hydrochar due to its severe pore collapse during the combustion process.

Study on Chemical Bond Dissociation and the Removal of Oxygen-Containing Functional Groups of Low-Rank Coal during Hydrothermal Carbonization: DFT Calculations.

The molecular structure model of lignite was constructed, and the dissociation and removal mechanism of different C-O bonds and oxygen-containing functional groups was investigated using density functional theory (DFT) calculations. First, the bond order and bond dissociation enthalpy (BDE) were analyzed to predict the strength of different chemical bonds, and differences in the BDE and bond order were related to the difference in the fragment structure and electronic effects. The first group to break during hydrothermal carbonization (HTC) is the methyl of Ph(CO)O-CH3, followed by the C-O of CH3-OC(O)OH; the hydroxyl in Ph-OH is the most thermally stable group, followed by the hydroxyl in CH3OC(O)-OH. In addition, the orbital localization analysis has also been carried out. All three chemical bonds of Ph(CO)OCH3 show the characteristics of σ bond, while Ph(C=O)OCH3 and Ph(CO)-OCH3 with the Mayer bond order (MBO) greater than 1 also contains certain π bond characteristics. The lignite van der Waals (vdW) surface electrostatic potential (ESP) was constructed and visualized, and the results showed that the oxygen-containing functional groups mainly contributed to the area with a large absolute ESP. Finally, weak interactions between water molecules and lignite at different sites were described by independent gradient model (IGM) analysis. Models A, B, and E formed weak interactions with the hydrogen bond as the main force; model E showed the weakest hydrogen bond, while model C showed van der Waals interaction as the dominant force. In addition, some steric effect was also observed in model D.

Multi-View Spatial-Temporal Graph Convolutional Networks With Domain Generalization for Sleep Stage Classification.

Sleep stage classification is essential for sleep assessment and disease diagnosis. Although previous attempts to classify sleep stages have achieved high classification performance, several challenges remain open: 1) How to effectively utilize time-varying spatial and temporal features from multi-channel brain signals remains challenging. Prior works have not been able to fully utilize the spatial topological information among brain regions. 2) Due to the many differences found in individual biological signals, how to overcome the differences of subjects and improve the generalization of deep neural networks is important. 3) Most deep learning methods ignore the interpretability of the model to the brain. To address the above challenges, we propose a multi-view spatial-temporal graph convolutional networks (MSTGCN) with domain generalization for sleep stage classification. Specifically, we construct two brain view graphs for MSTGCN based on the functional connectivity and physical distance proximity of the brain regions. The MSTGCN consists of graph convolutions for extracting spatial features and temporal convolutions for capturing the transition rules among sleep stages. In addition, attention mechanism is employed for capturing the most relevant spatial-temporal information for sleep stage classification. Finally, domain generalization and MSTGCN are integrated into a unified framework to extract subject-invariant sleep features. Experiments on two public datasets demonstrate that the proposed model outperforms the state-of-the-art baselines.

Comprehensive Study on the Feasibility of Pyrolysis Biomass Char Applied to Blast Furnace Injection and Tuyere Simulation Combustion.

Basic property analysis is the most comprehensive evaluation of metallurgical characteristics of blast furnace injection fuel. In this study, the basic properties of 16 types of pyrolysis biomass char samples were comprehensively investigated; the results showed that components harmful to a blast furnace, such as the ash content and alkali metal content of Jiangsu Suzhou woodblock char (B3), Jiangsu Changzhou branch char (B8), Jiangsu Zhangjiagang bamboo char (B10), and Jiangsu Zhangjiagang coconut shell char (B12) in all of the biomass char samples, are lower and close to the level of blast furnace injection bituminous coal. The grindability, particle size distribution, and safety all met the requirements of the blast furnace. Among them, the ash melting characteristic temperature of B3, B8, Jiangsu Zhangjiagang rice husk char (B11), and Shanghai soil remediation agent (B16) was greater than 1250 °C, indicating that they are not easy to block the blast furnace raceway and spray guns. Most of the biomass char samples had good combustibility, and the burnout temperature was less than 700 °C. A self-developed blast furnace injection combustion simulation experimental device was used to simulate the combustion behavior of biomass char in the blast furnace raceway tuyere, and the burnout rates of 16 biomass chars were measured. The results showed that that the burnout rate is related to both the volatiles and fixed carbon and the influence of volatiles on the burnout rate is greater than that of fixed carbon. The burnout rates of B3 and B8 were 77.12 and 67.03%, respectively. Above all, B3 and B8 showed good properties, but the burnout rate of B3 was higher, so B3 had the feasibility of applying to blast furnace injection, which indicates that woodblock char has the potential to be used as blast furnace injection fuel.

Multiple roles of core protein linker in hepatitis B virus replication.

Hepatitis B virus (HBV) core protein (HBc) contains an N-terminal domain (NTD, assembly domain) and a C-terminal domain (CTD), which are linked by a flexible linker region. HBc plays multiple essential roles in viral replication, including capsid assembly, packaging of the viral pregenomic RNA (pgRNA) into nucleocapsids, viral reverse transcription that converts pgRNA to the genomic DNA, and secretion of DNA-containing (complete) virions or genome-free (empty) virions. The HBc linker is generally assumed to act merely as a spacer between NTD and CTD but some results suggest that the linker may affect NTD assembly. To determine its role in viral replication, we have made a number of deletion and substitution mutants in the linker region, in either the presence or absence of CTD, and tested their abilities to support capsid assembly and viral replication in human cells. Our results indicate that the linker could indeed impede NTD assembly in the absence of CTD, which could be partially relieved by partial linker deletion. In contrast, when CTD was present, the linker deletions or substitutions did not affect capsid assembly. Deletion of the entire linker or its C-terminal part resulted in a partial defect in pgRNA packaging and severely impaired viral DNA synthesis. In contrast, deletion of the N-terminal part of the linker, or substitutions of the linker sequence, had little to no effect on RNA packaging or first-strand DNA synthesis. However, the N-terminal linker deletion and two linker substitution mutants were defective in the production of mature double-stranded viral DNA. Secretion of empty virions was blocked by all the linker deletions and substitutions tested. In particular, a conservative linker substitution that allowed mature viral DNA synthesis and secretion of complete virions severely impaired the secretion of empty virions, thus increasing the ratio of complete to empty virions that were secreted. Together, these results demonstrate that the HBc linker region plays critical and complex roles at multiple stages of HBV replication.

Common and Distinct Capsid and Surface Protein Requirements for Secretion of Complete and Genome-Free Hepatitis B Virions.

During the morphogenesis of hepatitis B virus (HBV), an enveloped virus, two types of virions are secreted: (i) a minor population of complete virions containing a mature nucleocapsid with the characteristic, partially double-stranded, relaxed circular DNA genome and (ii) a major population containing an empty capsid with no DNA or RNA (empty virions). Secretion of both types of virions requires interactions between the HBV capsid or core protein (HBc) and the viral surface or envelope proteins. We have studied the requirements from both HBc and envelope proteins for empty virion secretion in comparison with those for secretion of complete virions. Substitutions within the N-terminal domain of HBc that block secretion of DNA-containing virions reduced but did not prevent secretion of empty virions. The HBc C-terminal domain was not essential for empty virion secretion. Among the three viral envelope proteins, the smallest, S, alone was sufficient for empty virion secretion at a basal level. The largest protein, L, essential for complete virion secretion, was not required but could stimulate empty virion secretion. Also, substitutions in L that eliminated secretion of complete virions reduced but did not eliminate empty virion secretion. S mutations that blocked secretion of the hepatitis D virus (HDV), an HBV satellite, did not block secretion of either empty or complete HBV virions. Together, these results indicate that both common and distinct signals on empty capsids and mature nucleocapsids interact with the S and L proteins during the formation of complete and empty virions.IMPORTANCE Hepatitis B virus (HBV) is a major cause of severe liver diseases, including cirrhosis and cancer. In addition to the complete infectious virion particle, which contains an outer envelope layer and an interior capsid that, in turn, encloses a DNA genome, HBV-infected cells also secrete noninfectious, incomplete viral particles in large excess over the number of complete virions. In particular, the empty (or genome-free) virion shares with the complete virion the outer envelope and interior capsid but contains no genome. We have carried out a comparative study on the capsid and envelope requirements for the secretion of these two types of virion particles and uncovered both shared and distinct determinants on the capsid and envelope for their secretion. These results provide new information on HBV morphogenesis and have implications for efforts to develop empty HBV virions as novel biomarkers and a new generation of HBV vaccine.

Capsid Phosphorylation State and Hepadnavirus Virion Secretion.

The C-terminal domain (CTD) of hepadnavirus core protein is involved in multiple steps of viral replication. In particular, the CTD is initially phosphorylated at multiple sites to facilitate viral RNA packaging into immature nucleocapsids (NCs) and the early stage of viral DNA synthesis. For the avian hepadnavirus duck hepatitis B virus (DHBV), CTD is dephosphorylated subsequently to facilitate the late stage of viral DNA synthesis and to stabilize NCs containing mature viral DNA. The role of CTD phosphorylation in virion secretion, if any, has remained unclear. Here, the CTD from the human hepatitis B virus (HBV) was found to be dephosphorylated in association with NC maturation and secretion of DNA-containing virions, as in DHBV. In contrast, the CTD in empty HBV virions (i.e., enveloped capsids with no RNA or DNA) was found to be phosphorylated. The potential role of CTD dephosphorylation in virion secretion was analyzed through mutagenesis. For secretion of empty HBV virions, which is independent of either viral RNA packaging or DNA synthesis, multiple substitutions in the CTD to mimic either phosphorylation or dephosphorylation showed little detrimental effect. Similarly, phospho-mimetic substitutions in the DHBV CTD did not block the secretion of DNA-containing virions. These results indicate that CTD dephosphorylation, though associated with NC maturation in both HBV and DHBV, is not essential for the subsequent NC-envelope interaction to secrete DNA-containing virions, and the CTD state of phosphorylation also does not play an essential role in the interaction between empty capsids and the envelope for secretion of empty virions.IMPORTANCE The phosphorylation state of the C-terminal domain (CTD) of hepatitis B virus (HBV) core or capsid protein is highly dynamic and plays multiple roles in the viral life cycle. To study the potential role of the state of phosphorylation of CTD in virion secretion, we have analyzed the CTD phosphorylation state in complete (containing the genomic DNA) versus empty (genome-free) HBV virions. Whereas CTD is unphosphorylated in complete virions, it is phosphorylated in empty virions. Mutational analyses indicate that neither phosphorylation nor dephosphorylation of CTD is required for virion secretion. These results demonstrate that while CTD dephosphorylation is associated with HBV DNA synthesis, the CTD state of phosphorylation may not regulate virion secretion.

Phthalate concentrations in personal care products and the cumulative exposure to female adults and infants in Shanghai.

Phthalate esters (PE) are synthetic chemicals widely used in industry, and have been detected in personal care products (PCP). Recent findings of human reports demonstrated endocrine-disrupting action associated with phthalate exposures. The aims of this study were to (1) measure levels of 11 PE in 198 PCP collected from retail markets in Shanghai and (2) assess daily dermal exposure in adult females and infants. The health risk of cumulative exposure to eight PE on reproductive system function derived from dermal PCP use was further assessed by utilizing the hazard index (HI) approach. Diethyl phthalate (DEP) was the most frequently detected compound (29.8%), followed by diisobutyl phthalate (DiBP) (6.6%). The geometric mean (GM) concentrations of daily exposure to DEP, bis(2-methoxyethyl) phthalate (DMEP), DiBP, dibutyl phthalate (DBP), diphenyl phthalate (DPP), and bis(2-ethylhexyl) phthalate (DEHP) in female adults were 0.018, 0.012, 0.002, 0.001, 0.003, and 0.002 µg/kg body weight (bw)/d, respectively. The GM daily exposure levels to PE in infants and adult females were similar except for DEHP, which was higher in infants. DEP exposure was highest in both subpopulations at either GM or maximal level. All HI of 8 PE were far less than 1, ranging from 0.0002 to 0.005, indicating no cumulative reproductive risks to these populations. DBP, DMEP, and DEHP were three major contributors to the cumulative HI. In summary, the level of phthalate in PCP from Shanghai retail markets posed no apparent cumulative risk to adult females and infants in China.

[Clinical research on elongated needle combined with herb-partitioned moxibustion in the treatment of lumbar disc herniation].

OBJECTIVE: To optimize the best acupuncture therapy in the treatment of lumbar disc herniation (LDH) and to explore its mechanism in terms of immunology. METHODS: One hundred and eleven cases were randomized into an acupuncture-moxibustion group, an elongated needle group and a herb-partitioned moxibustion group, 37 cases in each group. In acupuncture-moxibustion group, penetration needling with elongated needle was applied at Dachangshu (BL 25), Guanyuanshu (BL 26) and Huantiao (GB 30), which was followed with herb-partitioned moxibustion at Shenque (CV 8) and Yaoyangguan (GV 3), etc, once a day. Elongated needle and herb-partitioned moxibustion were applied in the elongated needle group and herb-partitioned moxibustion group respectively. The efficacy of each group was observed after 21 treatments and the value of serum immunoglobulin was measured and analyzed before and after treatment. RESULTS: The effective rate was 97.3% (36/37) in acupuncture-moxibustion group, which was superior to 75.7% (28/37) in the elongated needle group and 73.0% (27/37) in the herb-partitioned moxibustion group (both P<0.05). The visual analogue scale (VAS), straight-leg raising range and motion range of the lumbar vertebra in three groups were all improved after treatment (all P<0.05), which was more significant in the acupuncture-moxibustion group (all P<0.05). The difference of value of serum immunoglobulin before and after treatment was significant in the acupuncture-moxibustion group (P<0.05), which was not in the elongated needle group and the herb-partitioned moxibustion group (both P>0.05). CONCLUSION: The therapy of elongated needle combined with herb-partitioned moxibustion achieves superior efficacy in the treatment of LDH as compared with elongated needle or herb-partitioned moxibustion therapy, and it can regulate the humoral immunity system of patients.

Maturation-associated destabilization of hepatitis B virus nucleocapsid.

The mature nucleocapsid (NC) of hepatitis B virus containing the relaxed circular (RC) DNA genome can be secreted extracellularly as virions after envelopment with the viral surface proteins or, alternatively, can be disassembled to release RC DNA (i.e., uncoating) into the host cell nucleus to form the covalently closed circular (CCC) DNA, which sustains viral replication and persistence. In contrast, immature NCs containing the viral single-stranded DNA or the pregenomic RNA are incompetent for either envelopment or uncoating. Little is currently known about how mature NCs, and not the immature ones, are specifically selected for these processes. Here, we have carried out a biochemical analysis of the different NC populations upon their separation through sucrose gradient centrifugation. We have found that the maturation of NCs is associated with their destabilization, manifested as increased protease and nuclease sensitivity, altered sedimentation during sucrose gradient centrifugation, and retarded mobility during native agarose gel electrophoresis. Also, three distinct populations of intracellular mature NCs could be differentiated based on these characteristics. Furthermore, mature NCs generated in vitro under cell-free conditions acquired similar properties. These results have thus revealed significant structural changes associated with NC maturation that likely play a role in the selective uncoating of the mature NC for CCC DNA formation and/or its preferential envelopment for virion secretion.

Cyclin-dependent kinase 2 phosphorylates s/t-p sites in the hepadnavirus core protein C-terminal domain and is incorporated into viral capsids.

Phosphorylation of the hepadnavirus core protein C-terminal domain (CTD) is important for viral RNA packaging, reverse transcription, and subcellular localization. Hepadnavirus capsids also package a cellular kinase. The identity of the host kinase that phosphorylates the core CTD or gets packaged remains to be resolved. In particular, both the human hepatitis B virus (HBV) and duck hepatitis B virus (DHBV) core CTDs harbor several conserved serine/threonine-proline (S/T-P) sites whose phosphorylation state is known to regulate CTD functions. We report here that the endogenous kinase in the HBV capsids was blocked by chemical inhibitors of the cyclin-dependent kinases (CDKs), in particular, CDK2 inhibitors. The kinase phosphorylated the HBV CTD at the serine-proline (S-P) sites. Furthermore, we were able to detect CDK2 in purified HBV capsids by immunoblotting. Purified CDK2 phosphorylated the S/T-P sites of the HBV and DHBV CTD in vitro. Inhibitors of CDKs, of CDK2 in particular, decreased both HBV and DHBV CTD phosphorylation in vivo. Moreover, CDK2 inhibitors blocked DHBV CTD phosphorylation, specifically at the S/T-P sites, in a mammalian cell lysate. These results indicate that cellular CDK2 phosphorylates the functionally critical S/T-P sites of the hepadnavirus core CTD and is incorporated into viral capsids.

Secretion of genome-free hepatitis B virus--single strand blocking model for virion morphogenesis of para-retrovirus.

As a para-retrovirus, hepatitis B virus (HBV) is an enveloped virus with a double-stranded (DS) DNA genome that is replicated by reverse transcription of an RNA intermediate, the pregenomic RNA or pgRNA. HBV assembly begins with the formation of an "immature" nucleocapsid (NC) incorporating pgRNA, which is converted via reverse transcription within the maturing NC to the DS DNA genome. Only the mature, DS DNA-containing NCs are enveloped and secreted as virions whereas immature NCs containing RNA or single-stranded (SS) DNA are not enveloped. The current model for selective virion morphogenesis postulates that accumulation of DS DNA within the NC induces a "maturation signal" that, in turn, triggers its envelopment and secretion. However, we have found, by careful quantification of viral DNA and NCs in HBV virions secreted in vitro and in vivo, that the vast majority of HBV virions (over 90%) contained no DNA at all, indicating that NCs with no genome were enveloped and secreted as empty virions (i.e., enveloped NCs with no DNA). Furthermore, viral mutants bearing mutations precluding any DNA synthesis secreted exclusively empty virions. Thus, viral DNA synthesis is not required for HBV virion morphogenesis. On the other hand, NCs containing RNA or SS DNA were excluded from virion formation. The secretion of DS DNA-containing as well as empty virions on one hand, and the lack of secretion of virions containing single-stranded (SS) DNA or RNA on the other, prompted us to propose an alternative, "Single Strand Blocking" model to explain selective HBV morphogenesis whereby SS nucleic acid within the NC negatively regulates NC envelopment, which is relieved upon second strand DNA synthesis.

[Heat sensitive moxibustion for treatment of nerve root cervical spondylosis].

OBJECTIVE: To observe the therapeutic effect of heat sensitive moxibustion treatment for nerve root cervical spondylosis. METHODS: One hundred and sixty cases were randomly divided into a heat sensitive moxibustion group (n = 54), a traditional hanging moxibustion group (n = 53) and an acupuncture group (n = 53). In heat sensitive moxibustion group, heat sensitive points were explored among acupoints on neck and nucha, lateral part of forearm and crus, etc. In traditional hanging moxibustion group and acupuncture group, Jiaji (EX-B 2) points, Fengchi (GB 20), Jianwaishu (SI 14) etc. were used for hanging moxibustion and acupuncture, respectively. And scores of Pain Rating Index (PRI), as well as therapeutic effect were evaluated before and after treatment. RESULTS: The effective rate was 98.0% (50/51) in the heat sensitive moxibustion group, 83.0% (39/47) in traditional hanging moxibustion group, and 89.6% (43/48) in acupuncture group. The therapeutic effect of heat sensitive moxibustion group was better than that of acupuncture group (P < 0.05), and it was better in acupuncture group than that of traditional hanging moxibustion group (P < 0.05); PRI scores were all decreased in three groups after treatment (all P < 0.001); pain alleviation in heat sensitive moxibustion group was better than that of acupuncture group (P < 0.05), and it was better in acupuncture group than that of traditional hanging moxibustion group (P < 0.05). CONCLUSION: The therapeutic effect of heat sensitive moxibustion treatment for nerve root cervical spondylosis is better than that of traditional hanging moxibustion and acupuncture.

Effect of the alterations in the fusion protein of measles virus isolated from brains of patients with subacute sclerosing panencephalitis on syncytium formation.

Measles virus (MV) is the causative agent of subacute sclerosing panencephalitis (SSPE) and viruses isolated from brains of the patients contain numerous mutations. We have previously demonstrated that the hemagglutinin (H) protein of MV SSPE strains can interact with the signaling lymphocyte activation molecule (SLAM) and an unidentified molecule on Vero cells, but not with CD46, as a receptor. The mechanism by which MV SSPE strains can induce cell-cell fusion in SLAM-negative Vero cells is not understood. We report here on the effect of mutations in the fusion (F) proteins of three MV SSPE strains on syncytium formation. The F proteins of the three SSPE strains were functional and co-expression with H protein from the MV wild-type or SSPE strains in this study induced formation of large syncytia in Vero cells as well as in cell lines expressing SLAM or CD46. Expression of chimeric F proteins of SSPE strains showed that amino acid substitutions in the F protein extracellular as well as cytoplasmic domain contributed to enhanced cell-cell fusion in Vero cells. These findings suggest a common molecular mechanism and a key role of the F protein for syncytium formation in cells expressing an unidentified third receptor for MV.

Alterations and diversity in the cytoplasmic tail of the fusion protein of subacute sclerosing panencephalitis virus strains isolated in Osaka, Japan.

We determined the nucleotide sequence of the fusion (F) gene of three strains (Osaka-1, -2, and -3) of nonproductive variants of measles virus (MV). These viral strains were isolated in Osaka, Japan, from brain tissues of patients with subacute sclerosing panencephalitis (SSPE). Phylogenetic analysis revealed a close relationship among the three strains of SSPE virus. The cytoplasmic tail of the F protein, predicted from sequence analysis of the gene, is altered in all three SSPE strains when compared to the MV field strains. However, the extent and mode of alteration are different in each strain. The F protein of the Osaka-1 strain has six nonconservative amino acid substitutions and a 29-residue elongation of its cytoplasmic tail. The F protein of the Osaka-3 strain has two nonconservative substitutions and a 5-residue truncation of its C-terminus. Although the termination codon is not altered in the F protein of the Osaka-2 strain, five or six amino acids are changed in the cytoplasmic tail of the F protein of the two sibling viruses of this strain. The significance of the altered cytoplasmic domain of the SSPE viruses in the SSPE pathogenesis is discussed.