| In the long time duration of studying on Bluetongue Virus of Hubei China strain 3, BTV-HbC3, We noted that BTV-HbC3 could be propagated well in HeLa cell line, a cell line derived from human cervical carcinoma, and later, we found it can even infect some other cancer cells. This inspired our imaginations of a therapeutic method for carcinoma: virotherapy of carcinoma. So, here we proceeded several experiments to explore whether BTV-HbC3 has the potential of becoming an oncolytic virus.First, by using BTV-HbC3 to infect some human and animal cancer cells including human lung cancer SPC-A-1 cells, human cervical carcinoma HeLa cells, human astrocytoma U251 cells, mouse-derived astrocytoma C6 cells and a normal cell strain: human embryonic lung cells separately, we could observe the cytopathic effects induced by BTV-HbC3 to investigate if all the tested cells are susceptible to the virus.At the same time, we titrated the TCID50 of BTV-HbC3 on all the tested cells, and used double immunodiffusing test in order to detect if there are BTV-HbC3 antigens in all the cells infected with BTV-HbC3, so that, we could investigate the propagation ability of progeny virus in these cell lines. Through these methods, we can distinguish if there are some differences between the infectivity of BTV-HbC3 to normal and to tumor cells.To improve the reliability of the results of double immunodiffusing test, Reverse transcription-PCR was used to detect the proliferations of BTV-HbC3 in these cells. We also used transmission electron microscope to observe the ultra structure morphology changes of the tested cells. Through this, we can very clearly to see the morphology sequent and morphgenesis sequent of interaction between the virus and all the tested cells.The results show: BTV-HbC3 could induce cytopathic effects on all the cells except human embryonic lung cells; double immunodiffusing test result could clearly display the Immunoprecipitation of antibody-antigen compounds between all the cells except human embryonic lung cells and anti- BTV-HbC3. Reverse transcription-PCR also can detect the specific nucleic acid sequence of BTV-HbC3 in all the cells except human embryonic lung cells.But, we found that, though BTV-HbC3 can replicate in all the tested tumor cells, the infectivity of it are not all the same to them.The most important result of these experiments is brought by transmission electron microscope. The photos show that almost every tumor cell strainsiiiinfected with BTV-HbC3 could produce different amount of bluetongue virus particles. In some cells, numerous virus particles arranged like crystals with many vacuum virus capsids. In C6 cell strains we observed some special images: condensed chromatin at the nuclear margin with many cytoplasmic vacuoles in different size. These images show the characters of cell apoptosis.These EM images clearly discovered that: (1) all the tested tumor cells came into being CPE; (2) the CPE can be divided into two kinds: The first one is those viruses propagate in a large amount and lyse tumor cells. The other is that viruses propagate to some degree and induce tumor cells' apoptosis.According to above results, we could primarily draw a conclusion that BTV-HbC does not infect normal human embryonic lung cells, but it can selectively replicate in tumor cells and induce different degree of cytopathic effects or induce cell apoptosis, and finally, kill all the tested tumor cells. Among all the tested cells, human lung cancer SPC-A-1 cells have the highest sensitivity to BTV-HbC.These experiments showed that BTV-HbC has the potential of targeted killing some kinds of tumor cells. Though the mechanism needs further study, these data can still provide the laboratory basis for approaching the possibility of BTV-HbC as an oncolytic virus. |
