A human lung squamous carcinoma was transplanted and passaged in Swiss-DF nude mice, called LSX-83, for more than five years in our laboratory. The morphological characteristics of the original tumor were maintained i...A human lung squamous carcinoma was transplanted and passaged in Swiss-DF nude mice, called LSX-83, for more than five years in our laboratory. The morphological characteristics of the original tumor were maintained in passages from 4 to 33. But from the 35th generation, an increasing amount of tonofilaments and nuclear segregation with typical features was found with electron microscopy. The C-type virus particles were first detected in extra cellular space after 40 passages. The viruses were observed in different stages of growth, but their distribution and number did not show apparent change up to 54 passages. Such findings suggest that LSX-83 cells probably possess certain barrier of resistance against C-type viruses. The relation between C-type viruses and the morphological changes of LSX-83 cells was discussed.展开更多
The purpose of this study was to understand the stability and possibility of back mutation of Japanese encephalitis （JE） attenuated vaccine virus strain SA14-14-2 HKs on molecular level. The E genes of the SA14-14-2...The purpose of this study was to understand the stability and possibility of back mutation of Japanese encephalitis （JE） attenuated vaccine virus strain SA14-14-2 HKs on molecular level. The E genes of the SA14-14-2 HKs vaccine virus and its PHK cells passaged virus （SA14-14-2 HK17 ）, its mouse brain passaged virus （SA14-14-2 SM1 ） were sequenced and compared with the E gene of parental SAI4 virus. The total RNA was extracted from infected Vero cells and amplified by RT-PCR. The RT-PCR products were purified and cloned into T-vector. Positive clones were screened, identified and sequenced. There were twelve nucleotides and eight amino acids substitutions between SA14 parent virus and SA14-34-2 PHKs vaccine virus. The SA14-14-2 PHK17 virus showed two additional mutations （E-331 and E-398） which were not back mutations. Although five additional mutations were found in SA14-34-2 SMt virus, only one （E-307） was back mutation. Genetic characteristics of the attenuated vaccine virus SA14- 34-2 were stable when it was passaged 37 times on PHK cells or one time in mouse brains.展开更多
文摘A human lung squamous carcinoma was transplanted and passaged in Swiss-DF nude mice, called LSX-83, for more than five years in our laboratory. The morphological characteristics of the original tumor were maintained in passages from 4 to 33. But from the 35th generation, an increasing amount of tonofilaments and nuclear segregation with typical features was found with electron microscopy. The C-type virus particles were first detected in extra cellular space after 40 passages. The viruses were observed in different stages of growth, but their distribution and number did not show apparent change up to 54 passages. Such findings suggest that LSX-83 cells probably possess certain barrier of resistance against C-type viruses. The relation between C-type viruses and the morphological changes of LSX-83 cells was discussed.
文摘The purpose of this study was to understand the stability and possibility of back mutation of Japanese encephalitis （JE） attenuated vaccine virus strain SA14-14-2 HKs on molecular level. The E genes of the SA14-14-2 HKs vaccine virus and its PHK cells passaged virus （SA14-14-2 HK17 ）, its mouse brain passaged virus （SA14-14-2 SM1 ） were sequenced and compared with the E gene of parental SAI4 virus. The total RNA was extracted from infected Vero cells and amplified by RT-PCR. The RT-PCR products were purified and cloned into T-vector. Positive clones were screened, identified and sequenced. There were twelve nucleotides and eight amino acids substitutions between SA14 parent virus and SA14-34-2 PHKs vaccine virus. The SA14-14-2 PHK17 virus showed two additional mutations （E-331 and E-398） which were not back mutations. Although five additional mutations were found in SA14-34-2 SMt virus, only one （E-307） was back mutation. Genetic characteristics of the attenuated vaccine virus SA14- 34-2 were stable when it was passaged 37 times on PHK cells or one time in mouse brains.
