SUSCEPTIBILITY OF CELL CULTURES FROM VARIOUS MAMMALIAN TISSUES TO THE INFECTION BY SHIGELLA

Abstract

Comparison of cell-infection rates by Shigella was made among primary or secondary cell cultures and established cell lines isolated from various mammalian tissues. Cell cultures originating from the guinea pig cornea and the mouse lung showed a high infection rate with virulent strains of Shigella flexneri 2a, 3a and S. dysenteriae 1. The infection rate in the former cell cultures was lower after a long period of subculture, while in the latter it was high even after more than 100 subcultures performed over 3 years. Cell cultures of both human and monkey origins including primary or secondary cultures from the intestine showed a low infection rate with all types of Shigella. By the cell culture procedures used in the present work, animal species-or organ-specificity as found in the natural susceptibility to Shigella infection did not show any consistent correlationship with the infection rate in the cell culture from corresponding animals or organs. Compared with other types of Shigella S. sonnei clearly showed a low cell infectivity. This fact agrees with the pathogenic behavior of S. sonnei which causes generally mild symptoms in human bacillary dysentery, experimental Shigellosis in monkeys, and keratoconjunctivitis in guinea pigs. No difference in cell-infection rate was observed between primary cultures (polygonal cells) of the guinea pig cornea, which acquired resistance in vivo after recovery from the local infection with a virulent strain of Shigella, and those of the untreated control cornea. Irrespective of whether or not the pretreatment was made, the presence of hyperirnmune serum against the infecting bacilli in the cell culture medium resulted in a decrease in the infection rate of cornea cells. This is considered to be caused by agglutination of the bacilli in extracellular environment.