Centrifugation and Rickettsiae and viruses onto cells and its effect on infection.

Abstract

SummaryA method for effective inoculation of cultured cells with some rickettsiae and larger viruses is described. Chick embryo entodermal cell monolayers were prepared either in standard screw-cap tubes or, when microscopic examination was required, in flat-bottomed tubes containing 12 mm round coverslips. Following addition of inoculum diluted in fresh nutrient, the tubes were centrifuged horizontally at 1600-1800 g for 1 hour at 20°C. By this procedure infection of cells with Rickettsia prowazekii was greatly enhanced (about 10,000-fold) over that obtained in stationary tubes, and susceptibility of entodermal cells appeared to be as great in centrifuged tubes as in intact embryo. Good enhancement was also obtained with psittacosis (about 100-fold) and trachoma (at least 10-fold) viruses and moderate enhancement with Coxiella burnetii. The same procedure was successfully used to enhance infection of cells from human skin cell line (HuS 2806) with psittacosis virus.