Role of cyclinD1 and CDK4 in the carcinogenesis induced by silica.

OBJECTIVE: To study the role of cyclinD1 and CDK4 in malignant transformation of human fetal lung diploid fibroblast cell line (2BS) induced by silica. METHODS: Recombination vectors with sense and antisense pXJ41-cyclinD1 and pXJ41-CDK4 were constructed, and then transfected into the malignant transformed cells induced by silica, respectively. At the same time, pXJ41-neo was used as the control. RESULTS: During the progress of the malignant transformation of 2BS cells induced by silica, cyclinD1 and CDK4 were overexpressed. Antisense RNA suppressed cyclinD1 and CDK4 gene expression in the antisense pXJ41-cyclinD1 and pXJ41-CDK4 transfected cells. Antisense RNA led to cell cycle arrest, resulting in lengthened G1 phase (the percentages of cells in the G1 phase changed from 45.1% to 52.7% and 58.0% for cyclinD1 and CDK4 transfected cells, respectively), and eventually attenuated the increase of the proliferation of malignant transformed cells induced by silica. Compared with malignant transformed cells induced by silica, cells transfected with antisense pXJ41-cyclinD1 and pXJ41-CDK4 showed obviously reduced growth rates. On the 8th day, the suppression rates were 58.69 and 77.43% (the growth rate of malignant transformed cells induced by silica was 100%), doubling time changed from 21.0 h to 31.4 h and 21.0 h to 42.7 h, respectively, the growth capacities on soft agar of cells transfected by antisense pXJ41-cyclinD1 and pXJ41-CDK4 decreased obviously. CONCLUSION: CyclinD1 and CDK4 play an important role in maintaining transformed phenotype of the cancer cells.

Protective Efficacy of the Conserved NP, PB1, and M1 Proteins as Immunogens in DNA- and Vaccinia Virus-Based Universal Influenza A Virus Vaccines in Mice.

The conventional hemagglutinin (HA)- and neuraminidase (NA)-based influenza vaccines need to be updated most years and are ineffective if the glycoprotein HA of the vaccine strains is a mismatch with that of the epidemic strain. Universal vaccines targeting conserved viral components might provide cross-protection and thus complement and improve conventional vaccines. In this study, we generated DNA plasmids and recombinant vaccinia viruses expressing the conserved proteins nucleoprotein (NP), polymerase basic 1 (PB1), and matrix 1 (M1) from influenza virus strain A/Beijing/30/95 (H3N2). BALB/c mice were immunized intramuscularly with a single vaccine based on NP, PB1, or M1 alone or a combination vaccine based on all three antigens and were then challenged with lethal doses of the heterologous influenza virus strain A/PR/8/34 (H1N1). Vaccines based on NP, PB1, and M1 provided complete or partial protection against challenge with 1.7 50% lethal dose (LD50) of PR8 in mice. Of the three antigens, NP-based vaccines induced protection against 5 LD50 and 10 LD50 and thus exhibited the greatest protective effect. Universal influenza vaccines based on the combination of NP, PB1, and M1 induced a strong immune response and thus might be an alternative approach to addressing future influenza virus pandemics.

[Role of cyclin D1 in carcinogenesis of human cells induced by quartz].

OBJECTIVE: To study the role of cyclin D1 in malignant transformation of human embryonic lung diploid fibroblasts (HELF) induced by quartz. METHODS: pXJ41-cyclin D1 expressing sense and antisense cyclin D1 RNA were transinfected into malignant transformed HELF induced by quartz with DNA recombination and gene transduction. The expression of cyclin D1 was detected with hybridization in situ and immunohistochemistry methods to analyze changes in cell growth, double multiplication time, distribution of cell cycles, colony forming ability on soft agar, etc., before and after cyclin D1 transduction. RESULTS: During the process of malignant transformation of HELF induced by quartz, cyclin D1 gene was overexpressed. Antisense pXJ41-cyclin D1 RNA could suppress the growth and proliferation of malignant transformed cells induced by quartz. Growth speed of antisense pXJ41-cyclin D1 transinfected cells decreased by 58.69% on the 8th day in culture, as compared to malignant transformed cells induced by quartz, and its double multiplication time prolonged from 21.0 h to 31.4 h. Antisense cyclin D1 RNA led to cell cycle arrest, resulting in lengthened G1 phase (proportion of cells in phase G1 increased to 52.7% from 45.1% and that of cells in phase S decreased to 33.1% from 40.3%). Colony forming rate reduced significantly and size of colony became smaller. CONCLUSIONS: Abnormal expression of cyclin D1 in cells related to their malignant transformation induced by quartz. Highly expressed cyclin D1 could play an important role in maintaining the transformed phenotype of malignant cells.

[Recombination and identification of sense and antisense cyclinD1 eukaryotic expression vectors].

The exogenous gene cyclinD1 cDNA was inserted into eukaryotic expression vector pXJ41-neo by gene transduction and recombination techniques. The recombinant was detected by electrophoresis. Results showed that the recombinant sense plasmid (pXJ41-cyclinD1) was digested by HindIII into 229 bp, 427 bp and 7554 bp; while the recombinant antisense plasmid was digested into 427 bp, 1184 bp and 6599 bp, implying that sense and antisense pXJ41-cyclinD1 eukaryotic expression vectors were successfully recombined. The finding from this study offers an effective tool to reveal the mechanism of the carcinogenesis of environmental and occupational hazards.

[The role of cycline dependent kinase 4 in the malignant transformation induced by silica].

OBJECTIVE: To study the role of cycline dependent kinase 4 (CDK4) in the malignant transformation of human fetal lung diploid fibroblast cell (2BS) induced by silica. METHODS: Recombination vectors with antisense pXJ41-CDK4 were constructed, and then were transfected into the malignant transformed cells induced by silica. In situ hybridization and immunohistochemistry were used to analyze the expression of CDK4. Cell growth curve, doubling time, cell cycle distribution and the growth capacities on soft agar were analyzed before and after antisense CDK4 RNA was transferred into malignant transformed cells induced by silica. RESULTS: During the malignant transformation of 2BS cells induced by silica, CDK4 gene was overexpressed. Antisense pXJ41-CDK4 transduction suppressed CDK4 gene expression in the antisense pXJ41-CDK4 transfected cells. Antisense CDK4 RNA led to cell cycle arrest, resulting in lengthened G1 phase (the percentages of cells in the G1 phase increased from 45.1% to 58.0%), and eventually attenuated the proliferation of malignant transformed cells induced by silica. At the 8th day, the suppression rates decreased by 77.43%. The doubling time prolonged from 21.0 h to 42.7 h. The growth capacities on soft agar of cells transfected by antisense pXJ41-CDK4 were decreased. CONCLUSION: CDK4 might play an important role in maintaining the transformed phenotype of the cancer cells.

A virus-like particle vaccine for coxsackievirus A16 potently elicits neutralizing antibodies that protect mice against lethal challenge.

Coxsackievirus A16 (CVA16) is one of the main causative agents of hand, foot and mouth disease (HFMD), which has been prevalent in the Asia-Pacific region over the last several years. However, no vaccine is yet available to prevent HFMD. Here we report the development of a virus-like particle (VLP) based experimental CVA16 vaccine. CVA16 VLPs were produced in insect cells by co-expression of the P1 and 3CD proteins of CVA16 using recombinant baculoviruses. Biochemical and biophysical analyses showed that CVA16 VLPs consisted of processed VP0, VP1 and VP3, and were present as ≈ 30 nm spherical particles. Immunization with VLPs potently elicited CVA16-specific serum antibody responses in mice. Anti-VLP sera strongly neutralized in vitro both the homologous and heterologous strains of CVA16. More importantly, passive immunization with anti-VLP sera conferred protection against lethal CVA16 challenge in neonate mice, indicating a humoral mechanism of protection. Collectively, our results represent a successful first step toward the development of a safe and effective vaccine against CVA16 infection.

SARS-CoV spike proteins expressed by the vaccinia virus Tiantan strain: secreted sq protein induces robust neutralization antibody in mice.

The spike (S) glycoprotein of severe acute respiratory syndrome coronavirus (SARS-CoV) is a major target in the development of diagnostic assays and vaccines, but its antigenic and immunogenic properties remain unclear. Seven SARS-CoV spike proteins (S, SQ, S1, RBD, S2, S2Q, and CX) were generated using the modified vaccinia virus (Tiantan strain) as a vector, and their antigenicity and immunogenicity were evaluated. The secreted SQ protein in which the transmembrane domain was deleted, as well as the full-length spike protein, showed the most potential to induce the production of neutralizing antibody (nAb) in mice. S1 and RBD proteins initialized significantly lower levels of nAb production. In addition, the S proteins were recognized specifically by the sera of convalescent patients with SARS, and that of mice immunized with inactivated SARS-CoV, but did not react with anti-sera of HCoV-OC43 or HCoV-229E, or sera from healthy donors (although RBD showed a false-positive in 1 of 55 control samples of human sera). Our results demonstrate that SQ protein may be an effective vaccine candidate and a convenient and safe diagnostic antigen for SARS-CoV.

[Development and application of a safe SARS-CoV neutralization assay based on lentiviral vectors pseudotyped with SARS-CoV spike protein].

The severe acute respiratory syndrome-associated coronavirus (SARS-CoV) spike protein (S) is a major target for neutralizing antibody. To develop and apply a safe neutralization assay for SARS-CoV, lentiviral SARS-CoV S pseudotypes had been constructed based on a three plasmid system, which contained pVRC8304 (harboring codon optimized full-length SARS-CoV S protein), pCMV delta 8. 2 (HIV-1 gag/pol construct) and pHR'CMV EGFP (the green fluorescent protein reporter construct). The pseudo-typed lentiviral particles were used to develop an in vitro microneutralization assay that was both sensitive and specific for SARS-CoV neutralizing antibody. We used this assay to determine the titers of the neutralizing antibodies (Nabs) in serum samples from mice immunized with various rVVs expressing different S fragments of SARS-CoV. The serum antibodies derived from S and various segments of S1 region neutralized SARS-CoV in vitro. No cross-neutralization occurred with the goat antiserum prepared with inactivated HCoV-OC43 or HCoV-229E. Neutralization titers measured by this assay were highly parallel with those measured by the assay using live SARS-CoV. Because the pseudotype assay does not require handling live SARS virus, it is a useful tool to determine serum neutralizing titers during natural infection and the preclinical evaluation of candidate vaccines.

[Acute toxicity and immunoprotection of recombinant apxI toxin of Actinobacillus pleuropneumoniae in mice].

Acute toxicity and immunoprotection of Actinobacillus pleuropneumoniae (APP) ApxI toxin recombinant proteins (include crude inclusion bodies and refolded recombinant protein) were evaluated in mice, and compared with the natural ApxI extracted from culture supernatant of APP serotype 10. In the acute toxicity experiment, the three proteins were intraperitoneally injected into Kunming mice in a dose of 200microg per mouse. The body and organ weight, heamatological and biochemical indexes were examined at 24h, 7 days and 14 days post administration. There was no death after the intraperitoneal administration of the three proteins, and no significant change was found in the body weight, organ indexes, heamatological and biochemical indexes. To study their immunoprotection, the three proteins were emulsified with Freund's adjuvant respectively and vaccinated the mice twice with a 2-week of interval. Two weeks after the second vaccination, the mice were challenged intraperitoneally with a lethal dose of APP serotype 10 (1.09 x 10(8) cfu), and serums were examined by an ApxI-specific ELISA. The results revealed that the recombinant protein had a good immunogenicity and could induce protection immune reaction.