title: Isolation of a temperature-sensitive dengue-2 virus under conditions suitable for vaccine development.
abstract: Dengue virus, type 2, in viremic human sera and after passage in cell cultures produces mixtures of small and large plaques when assayed in LLC-MK2 cells. Clones of dengue virus type 2 obtained by plaque selection in primary green monkey kidney cell cultures were tested for temperature sensitivity in vitro and for virulence by intracerebral inoculation of suckling mice. Sublines of a small-plaque clone were found to have lower nonpermissive temperatures than the parent virus by both plaque formation and release of infectious virus into the culture media. Small-plaque sublines were significantly less virulent in suckling mice than was the parent virus. Sublines from a large-plaque clone were not temperature sensitive and closely resembled parent virus mixed-plaque morphology. When small-plaque sublines were serially passaged using undiluted inocula, reversion occurred as evidenced by the appearance of large plaques and return of mouse virulence. Small-plaque virus could be maintained through several serial passages without reversion by using low-input inocula. Desirable passage history as well as temperature-sensitive and attentuation characteristics of the S-1 small-plaque subline make it appear suitable as a vaccine candidate virus.
mesh_terms: D000818:Animals; D002460:Cell Line; D003716:Dengue Virus / Q000302:isolation & purification* / Q000472:pathogenicity; D005827:Genetics, Microbial; D006801:Humans; D051379:Mice; D013696:Temperature; D010948:Viral Plaque Assay; D014765:Viral Vaccines / Q000302:isolation & purification*; D014776:Virus Cultivation; D014779:Virus Replication
chemical_list: D014765:Viral Vaccines