id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
cord-321602-88b2h06y	Lv, Chenfei	Construction of an infectious bronchitis virus vaccine strain carrying chimeric S1 gene of a virulent isolate and its pathogenicity analysis	2020-08-19		.txt	text/plain	4902	266	58	The full-length genomic cDNA of IBV vaccine strain H120 was constructed in pBAC vector from four IBV fragment subcloning vectors by homologous recombination, which contained the CMV promoter at the 5′ end and the hepatitis D virus ribozyme (HDVR) sequence and bovine growth hormone polyadenylation (BGH) sequence after the polyA tail at the 3′ end of the full-length cDNA. To construct the full-length cDNA of IBV H120 strain, total RNA was extracted from the allantoic fluid of SPF chicken embryonated eggs infected with H120 and transcribed to cDNA by reverse transcriptase using the Thermo Scientific RevertAid First-Strand cDNA Synthesis Kit (Thermo Fisher, USA). The SC021202 S1 gene containing same homology arms to those of the H120F4 was amplified from total RNA of allantoic fluid of SPF chicken embryonated eggs infected with IBV SC021202 by RT-PCR with the primers SCS1-F and SCS1-R listed in Table 1 and was then inserted into pBAC-F4-△S1 by the same homologous recombination process using the ClonExpress one-step cloning kit (Vazyme Biotechnology, China).	./cache/cord-321602-88b2h06y.txt	./txt/cord-321602-88b2h06y.txt