id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
cord-004751-4vl0cvyq	Mostow, S. R.	The behaviour in vitro of attenuated recombinant influenza viruses	1973		.txt	text/plain	2245	132	60	Influenza strains produced by recombination and tested as possible live vaccine candidates were studied in organ cultures of trachea. Two strains which proved to be too virulent in human volunteers regularly caused damage to the ciliated epithelium and viruses grew to high titre. Attenuated influenza viruses have been produced recently by genetic recombination of avirulent laboratory-adapted strains and virulent parents (BEARE and HALL, 1971; McCAHo~ and SCHILD, 1972) . This method, which is the most rapid means of producing attenuated influenza strains to date, results in a spectrum of both attenuated and virulent clones as judged by their effects in human volunteers. The use of L-15 medium and rolling the screw-topped tubes prolonged the survival of the ciliated epithelium beyond that obtained using other standard media, and, in the conditions finally used, the human embryo trachea regularly survived for periods of 30--50 and occasionally 90 days. The recombinant viruses did not cause ciliary damage, but at 5 days the growth in ferret epithelium was similar to that in human tissue.	./cache/cord-004751-4vl0cvyq.txt	./txt/cord-004751-4vl0cvyq.txt