Selection of attenuated dengue 4 viruses by serial passage in primary kidney cells. III. Reversion to virulence by passage of cloned virus in fetal rhesus lung cells.
Two strains of primary dog kidney-passaged dengue (DEN) 4 (H-241) virus cloned by terminal dilution (PDK 24-TD3 and 35-TD3) were propagated in fetal rhesus lung (FRhL) cells to produce candidate vaccine virus seeds. Both serial passage and prolonged replication of PDK 24-TD3 in FRhL resulted in appearance of medium and large plaques in LLC-MK2 assays. When picked, these plaques proved to contain temperature-resistant, monkey-virulent revertants. Serial passage and prolonged replication of PDK 24-TD3 in LLC-MK2 cells did not result in reversion; but, prolonged replication in PDK cells did. Passage of PDK 35-TD3 in FRhL cells resulted in appearance of medium size plaques which, when picked, yielded temperature sensitive (ts) (38.5 degrees C) viruses of low monkey-virulence. Because of its stability in monkeys and FRhL cells, reduced monkey virulence and ts property. PDK 35-TD3 is a promising candidate for trial in man.
D000818:Animals; D000914:Antibodies, Viral / Q000096:biosynthesis; D002478:Cells, Cultured; D003716:Dengue Virus / Q000254:growth & development / Q000276:immunology / Q000472:pathogenicity*; D004285:Dogs; D005333:Fetus; D007668:Kidney / Q000382:microbiology; D008168:Lung / Q000382:microbiology; D008253:Macaca mulatta; D013696:Temperature; D010948:Viral Plaque Assay; D014774:Virulence; D014776:Virus Cultivation
D000914:Antibodies, Viral