The ability of passage in HeLa cells to attenuate flaviviruses was investigated for three different strains of the mosquito-borne West Nile (WN) virus and two tick-borne viruses, louping-ill and Langat. One strain of WN virus, Sarawak, was attenuated 4000-fold for adult mice by intraperitoneal or intranasal challenge after six HeLa passages. The HeLa-passaged virus was also found to be antigenically different and temperature-sensitive in its growth characteristics compared with the parent. After six HeLa cell passages the Egypt 101 and Smithburn strains of WN virus lost their ability to infect monkey kidney cells and no longer killed adult mice, although inoculated animals became sick for several days. In contrast, two tick-borne flaviviruses remained as virulent for mice after six HeLa passages as the parent non-HeLa-passaged virus. Neither of the tick-borne viruses exhibited characteristics associated with temperature sensitivity. The results, therefore, indicate that the mosquito-borne, but not tick-borne, flaviviruses can be attenuated by very few passages in HeLa cells. This observation may provide a model system with which to analyse the molecular basis of attenuation and/or virulence of mosquito-borne flaviviruses.
BarrettA. D. T.,
PrydeA.,
MedlanA. R.,
LedgerT. N.,
WhitbyJ. E.,
GibsonC. A.,
DeSilvaM.,
GrovesD. J.,
LangleyD. J.,
MinorP. D.1989; Examination of the envelope glycoprotein of yellow fever vaccine viruses with monoclonal antibodies. Vaccine 7:333–336
CalisherC. H.,
KarabatsosN.,
DalrympleJ. M.,
ShopeR. E.,
PorterfieldJ. S.,
WestawayE. G.,
BrandtW. E.1989; Antigenic relationships between flaviviruses as determined by crossneutralization tests with polyclonal antisera. Journal of General Virology 70:37–43
ConverseJ. L.,
KovatchR. M.,
PulliamJ. D.,
NagleS. C.JrSynderE. M.1971; Virulence and pathogenesis of yellow fever virus serially passaged in tissue culture. Applied Microbiology 21:1053–1057
EckelsK. H.,
BrandtW. E.,
HarrisonV. R.,
McCowanJ. M.,
RussellP. K.1976; Isolation of a temperature-sensitive dengue-2 virus under conditions suitable for vaccine development. Infection and Immunity 14:1221–1224
HahnC. S.,
DalrympleJ. M.,
StraussJ. H.,
RiceC. M.1987; Comparison of the virulent Asibi strain of yellow fever virus with the 17D vaccine strain derived from it. Proceedings of the National Academy of Sciences U.S.A.: 842019–2023
HardyF. M.1963; The growth of Asibi strain yellow fever virus in tissue culture. II. Modification of virus and cells. Journal of Infectious Diseases 113:9–14
HearnH. J.JrSoperW. T.,
MillerW. S.1965; Loss in virulence of yellow fever virus serially passaged in HeLa cells. Proceedings of the Society for Experimental Biology and Medicine 119:319–322
HearnH. J.JrChappellW. A.,
DemchakP.,
DominickJ. W.1966; Attenuation of aerosolised yellow fever virus after passage in cell culture. Bacteriological Reviews 30:615–623
MathisC.,
SellardsA. W.,
LaigretJ.1928; Sensibilite du Macaca rhesusau virus de la fievre jaune. Compte rendu hebdomadaire des seances de l’Académie des sciences 186:604–606
MurphyL. C.,
BlackfordV. L.,
GleiserG. A.1955; Study of the properties of the virus of Venezuelan equine encephalomyelitis modified by in vitrocultivation in HeLa cells. American Journal of Veterinary Research 16:521–524
RiceC. M.,
LenchesE. M.,
EddyS. R.,
ShinS. J.,
SheetsR. L.,
StraussJ. H.1985; Nucleotide sequence of yellow fever virus: implications for flavivirus gene expression and evolution. Science 229:726–733
StarkC.,
KennedyS. I. T.1978; The generation and propagation of defective-interfering particles of Semliki Forest virus in different cell types. Virology 89:285–299
TheilerM.,
SmithH. H.1937; Effect of prolonged cultivation in vitroupon pathogenicity of yellow fever virus. Journal of Experimental Medicine 65:767–786
YuY. X.,
ZhangG. M.,
GuoY. P.,
LiH. M.1988; Safety of a live attenuated Japanese encephalitis virus vaccine (SA-14–14–2) for children. American Journal of Tropical Medicine and Hygiene 39:214–217