Molecular epidemiological study on prevalence of human papillomaviruses in patients with common warts in Beijing area / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To study the circulation, distribution, and genomic diversity of HPVs in common warts in Beijing area of China.</p><p><b>METHODS</b>Forty eight patients with pathologically diagnosed common warts were screened for the presence of HPV with HPV type-specific PCR and direct sequencing analysis. The genomic diversity of HPVs prevalent in Chinese patients was analyzed based on LCR.</p><p><b>RESULTS</b>Forty one (85.5%) samples were positive for HPV DNA, 13 (31.7%)--HPV-57, 12 (29.3%)--HPV-1a, 7 (17%)--HPV-27 and 5(12.2%)--HPV-2a. Four cases were infected with two different HPV types, two (4.9%) with HPV-1a and HPV-27, one (2.4%) with HPV-1 and HPV-57 and one (2.4%) with HPV-27 and HPV-57. In contrast to the prevalence of single strain of novel HPV-57 variant and HPV-1 prototype, two HPV-2 and three HPV-27 novel variants were found to circulate in Beijing.</p><p><b>CONCLUSION</b>HPV-1, -2, -27 and -57 are predominantly prevalent in patients with common warts in Beijing.</p>

Alternations of tau protein and its phosphorylated profiles in the experimental hamsters infected by scrapie agents 263K and 139A / 病毒学报

In human prion diseases, phosphorylated-tau deposition has been described in a rare genetic form, Gerstmann-Straussler-Scheinker disease, but is not considered part of the neuropathological picture of Creutzfeldt-Jakob disease. To investigate the possible changes of tau and phosphorylated tau (Ser396/Ser404) in transmissible spongiform encephalopathies (TSEs), the expressions and transcriptions of above biological factors in the brain tissues of 263K- and 139A-infected hamsters were evaluated by Western blots and Real Time PCR, respectively, followed by quantitative analyses of immunoblot images and relative transcriptional levels compared with normal animals. The contents of total tau increased, but phosphorylated tau at Ser396 and Ser404 decreased, regardless of the types of scrapie agents and clinical incubations. Transcriptions of two tau isoforms were also markedly increased. These findings suggested that dephosphorylation of tau at Ser396/Ser404 was a illness-correlative phenomenon in TSEs. Alterations of tau and phosphorylated tau (Ser396/Ser404) were either intermediate or consequent events in TSE pathogenesis and proposed the potential linkage of these bioactive proteins with the pathogenesis of prion diseases.

Establishment of a sandwich ELISA method for detection of vascular endothelial growth factor in serum samples of hepatocellular carcinoma patients / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To establish a sandwich ELISA method for detecting vascular endothelial growth factor (VEGF) in sera of population and the patients with hepatocellular carcinoma (HCC).</p><p><b>METHODS</b>Full length and two truncated human VEGF cDNA sequences were amplified from a commercial plasmid pBLAST49-hVEGF by PCR and inserted into the prokaryotic-expression plasmid pET-32a or pGEX-2T. Various VEGF proteins were expressed and purified from E. coli in His-Trx or GST fusion forms. The specific VEGF antibodies were elicited in experimental rabbits and mice by immunization of the full length VEGF fusion protein His-Trx-VEGF1-165. After purification of antibodies with chromatograph of Protein G, a sandwich ELISA technique was established. Serum VEGF levels were evaluated in 229 adults and 291 HCC patients.</p><p><b>RESULTS</b>SDS-PAGE displayed that the molecular weights of the expressed full length (His-Trx-VEGF1-165), N-terminal (His-Trx-VEGF1-100) and C-terminal (GST-VEGF100-165) human VEGF fusion proteins were about 38KD, 31KD, and 33KD, respectively. Western blots confirmed that the prepared antisera were able to recognize both prokaryoticly and eukaryoticly expressed recombinant VEGF proteins. Assays of serially diluted His-Trx-VEGF1-100 by the established sandwich ELISA method showed that the linear range of the standard curve was 0.625-320 ng/mL, with the squared correlation coefficient R2 = 0.991. Screening of a serum panel containing 291 serum samples of HCC patients and 229 health adults revealed that the average VEGF level in HCC patients was higher than that in healthy controls, with a statically significant difference.</p><p><b>CONCLUSION</b>The established sandwich ELISA reflects the level of serum VEGF and provide scientific basis for screening metastasis and recurrence of HCC using serum VEGF as an index.</p>

Establishment of an assay for PrP(Sc) detection based on streptomycin precipitation / 病毒学报

To establish a new Western blotting assay for PrP(Sc) detection, we optimized the Western blotting assay with a precipitation procedure of streptomycin sulfate. After digestion with PK, 10% scrapie infected hamster brain homogenates were incubated with 60 mmol/L streptomycin and the precipitated PrP(Sc) was recovered by centrifugation. The enrichment of PrP(Sc) by streptomycin sulfate precipitation was evaluated using Western blotting assay. The results showed streptomycin could bind to PK-treated PrP(Sc), forming high molecular masses, but not influence the glycosylated patterns on SDS-PAGE. Western blot assay revealed that the detective sensitivity of the streptomycin-precipitation PrP(Sc) was remarkably improved. As a sensitive, specific, rapid and flexible protocol for PrP(Sc), the protocol in this study has the potential utility, alone or combined with other techniques, for the detection of low level PrP(Sc) in the specimens from central nerve system, or from peripheral organs or body fluids.

Expression of cytosolic PrP and analysis of its cytotoxic activities / 病毒学报

In order to study the physicochemical characteristics of cytosolic PrP (CytoPrP) and evaluate its possible influence on cell viability, a recombinant plasmid expressing human CytoPrP eukaryoticly was constructed and transfected into human neuroblastoma cell line SH-SY5Y transiently. Proteinase-resistant activities of CytoPrP were evaluated by a proteinase K (PK) digestion and cytotoxic effects of CytoPrP were tested by MTT assay and Trypan Blue cell-counting. The presence of CytoPrP in cytoplasm after transfection was controlled by the presence of protease inhibitor. Compared with wild-type PrP, CytoPrP possessed relatively stronger PK-resistant activities. Obvious cytotoxic effects were observed in the cells after inducement of CytoPrP in cytoplasm by protease inhibitor, showing a dose-dependent manner. The results provide useful scientific evidences for further studies of potential role of CytoPrP in pathological mechanism of prion disease.

Establishment of PrP(Sc) conversion based on serial PMCA in vitro / 病毒学报

In order to establish an amplification system in vitro with which the PrP(Sc) is able to convert PrP(C) into proteinase K-resistant isoform infinitely and whether this system is more efficient than conventional protein misfolding cyclic amplification (PMCA), scrapie strain 263K-infected hamster's brain homogenate and homologous normal brain homogenate were prepared, respectively. A new methodology, namely serial PMCA, was utilized to reveal the continuous propagation ability of PrP(Sc). Totally 8 rounds of serial PMCA were proceeded and each round contained 48 cycles of alternative sonication and incubation. Simultaneously 144 cycles of conventional PMCA was used as a control. The results showed the PrP(Sc) from hamsters' brain tissues of scrapie agent 263K could replicate efficiently and infinitely with serial PMCA compared with finite propagation of PrP(Sc) with conventional PMCA system. The study of PrP(Sc) continuous propagation in brain homogenate with serial PMCA may further provide insight into the unsettled mechanism of prions misfolding and replication and apply to detect trace amount of PrP(Sc).

PrP protein can bind to protein kinase CK2 both in native and recombinant forms in vitro / 病毒学报

To explore the possible molecular interaction between CK2 and PrP, the full length sequences of human CK2alpha and CK2beta genes were amplified with RT-PCR using the mRNA from cell line SH-SY5Y as the template, and then the fusion proteins HIS-CK2alpha and GST-HIS-CK2beta were expressed in E. coli. The interaction between CK2 and PrP was evaluated with immunoprecipitation and pull-down assays. The results demonstrated that recombinant PrP bound specifically with CK2alpha, but not with CK2beta. The native CK2 and PrP in the hamster brains interacted each other, forming protein complexes. The domain responsible for interacting with CK2alpha was located at the C-terminal segment of PrP (residues 90-231). This study proposed reliable experimental data for the molecular interaction between PrP and CK2alpha, both in recombinant and native categories. These results supply scientific clues for further assessing the potential biological significance of the interaction of PrP with CK2 and possible role of CK2 in the pathogenesis of prion diseases.

Preliminary analyses for influence of mutant PrPs with different number of octapeptide / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>The present study was conducted to understand the effects of PrP in different octapeptide repeats on proliferation of HeLa cells.</p><p><b>METHODS AND RESULTS</b>Mutant PrPs with octapeptide repeat insertion were transiently expressed in HeLa cells and their results of MTT assay showed stronger cytotoxic effect on the proliferation of cells than wild-type PrP. Annexin V/PI assay also demonstrated that the expression of mutant PrPs was much easier to induce apoptosis than wild-type in HeLa cells. The percentage of both early and late stage apoptosis in mutant groups were significantly higher than that of wild type.</p><p><b>CONCLUSION</b>These data suggest that the expression of mutant PrPs associated with familial CJD is much easier to induce apoptosis in cultured cells than expression of wild type PrP.</p>

Generation and identification of phage engineering antibodies library against hamster prion protein / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>Generation and Identification of Phage Engineering Antibodies Library against Hamster Prion Protein.</p><p><b>METHODS</b>Fab antibodies were identified and confirmed. BALB/c mice were immuned with PrP proteins. After the third immunization, the total RNA was extracted from the mice spleens. The genes of heavy Fd Fragments and light chain of antibodies amplified by a series of specific primers of human IgG Fab fragment were cloned into phagemid vector pComb3.</p><p><b>RESULTS</b>The combinatorial Fab library were constructed successfully and the cloning efficiencies both of light chain and Fd fragments were about near 10(6). The Fab library were panned by four cycles and screened with purified haPrP23-231 antigen on microtiter plates. 12 mAbs were isolated after four cycles of panning, five of which were sequenced and resulted sequence data were analyzed by alignment with GenBank immunoglobulin genes. Two strain of new heavy and light chain genes of Fab antibodies were identified and confirmed.</p><p><b>CONCLUSION</b>The research in this article will provide foundation for study of diagnosis and therapy of prion.</p>

Interaction between various PrP segments and GFAP in vitro / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To study the potential interaction between PrP protein and glial fibrillary acidic protein (GFAP) and identify the binding region within PrP with GFAP.</p><p><b>METHODS</b>The supernatant of healthy and scrapie-infected hamsters' brain homogenate was prepared, while various recombinant PrP or GFAP proteins were expressed using prokaryotic-expressing or in-vitro translation system. The possible molecular interaction between PrP proteins and GFAP was tested by Pull-down and immunoprecipitation assays.</p><p><b>RESULTS</b>Both native PrP(C) and its protease-resistant isoform (PrP(Sc)) formed complexes with the native GFAP. The full-length recombinant PrP proteins interacted with GFAP. The domain responsible for interacting GFAP was located at C-terminal of PrP (residues 91 to 231).</p><p><b>CONCLUSION</b>The studies of the association of PrP with GFAP may further provide insight into a potential role of GFAP in the biological function of PrP and the pathogenesis of prion disease.</p>

Interaction analysis between various PrP fusion proteins and the tubulin in vitro / 病毒学报

In order to further study the potential interaction between PrP protein and the tubulin and identify the binding region in PrP with tubulin, native tubulin was extracted from rabbit brian tissues, while various recombinant PrP proteins were expressed and purified. The possible molecular interaction between various PrP fusion proteins and tubulin was tested by pull-down and immunoprecipitation assays. Remarkable molecular interaction between the full length PrP and tubulin was observed by pull-down and immunoprecipitation assays. Subsequently, the binding regions within PrP with tubulin were firstly mapped in the aa 23 -- 91 region within N-terminus of PrP peptide. The studies of the association of PrP with tubulin may further provide insight into the unresolved mechanism of active transport of PrP protein in neurons and possible cellular pathways by which prion causes disease.