Chromosome Studies of Human Cells Infected in utero and in vitro With Rubella Virus. ∗

Summary

A cytologic study of meta-phase chromosomes was undertaken to determine if damage to the genetic apparatus of human cells may be induced by rubella virus and whether such damage produces the pathology seen in newborns from mothers infected early in pregnancy. Fibroblast cell strains were initiated in vitro from embryonic material obtained by therapeutic abortion of fetuses from, rubella-infected mothers. Embryonic material from spontaneous and non-rubella therapeutic abortions yielded similar cell strains for infection in vitro. The results from both types of studies were as follows: (a) Virus shedding cell strains were obtained from all types of organs cultivated, which indicated wide dissemination of virus in the fetuses from rubella-infected mothers, (b) Chronic infection could readily be established by in vitro infection and no cytopathic effect was noted, (c) Although many strains continued to shed virus throughout months of in vitro cultivation, no changes in growth properties occurred with the exception that infected strains from lung tissue showed limited growth capacities, (d) From observations of over 2000 metaphases, neither obvious chromosomal rearrangements nor non-disjunctional changes were observed in strains infected naturally or experimentally, (e) Among 17 rubella abortion-derived cell strains there was a marked elevation in frequency of chromosome breakage in 3 instances (18%, 29%, 68%). (f) A correlation between virus shedding in vitro and increased chromosome breakage was noted although this was not complete, (g) The combined average frequency of chromosome breakage in one set of 7 rubella-abortion strains was 18%; in the other set of 9 abortus strains, 9.8%. (h) Similarly, a slight, but significant elevation in average chromosome break frequency (9,8%) was obtained in four cell strains which had been experimentally infected in vitro with rubella virus (uninfected cells: 5.2%).