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A cDNA clone for factor 10 (FX) isolated from chicken embryo inserted into the mammalian cell expression vector pCDNA3.1 was transfected into the baby hamster kidney (BHK-21) cell line. The generated BHK-21 cells with inducible expression of FX were used to investigate the efficacy of the serine transmembrane protease to proteolytic activation of influenza virus hemagglutinin (HA) with monobasic cleavage site. Data showed that the BHK-21/FX stably expressed FX after ten serial passages. The cells could proteolytically cleave the HA of low pathogenic avian influenza virus at multiplicity of infection 0.01. Growth kinetics of the virus on BHK-21/FX, BHK-21, and MDCK cells were evaluated by titrations of virus particles in each culture supernatant. Efficient multicycle viral replication was markedly detected in the cell at subsequent passages. Virus titration demonstrated that BHK-21/FX cell supported high-titer growth of the virus in which the viral titer is comparable to the virus grown in BHK-21 or MDCK cells with TPCK-trypsin. The results indicate potential application for the BHK-21/FX in influenza virus replication procedure and related studies. [ABSTRACT FROM AUTHOR]

Background: In this study, the pilot production of aerobic bioreactor tropical theileriosis vaccine was optimized with the aim of immunological assays for further mass production. Methods: We have shown earlier the delayed type hypersensitivity (DTH) assay could be used for evaluating the immunity and memory cells against specific Theileria antigen in vaccinated animals. In addition, TNF-α is the principle cytokine in modulating the cytotoxic activity of cytotoxic T-lymphocytes (CTL). Immunological analysis of the vaccine was performed by using two cell mediated immunity (CMI) in vitro and in vivo DTH test (Theilerin) and TNF-α assay. Results: The results of immune responses of susceptible immunized cattle by bioreactor vaccine in comparison with conventional flask vaccine revealed a significant stimulation of immune cells by transcription of high level of TNF-α and positive reaction against Theileria antigen in Theilerin skin test (DTH). Conclusion: The equal immunological results achieved in both above mentioned vaccines verified the satisfactory immunity for aerobic bioreactor theileriosis vaccine for advance mass vaccination in the field on a large scale. [ABSTRACT FROM AUTHOR]