id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
cord-263178-lvxxdvas	Shan, Dan	Effects of hypervariable regions in spike protein on pathogenicity, tropism, and serotypes of infectious bronchitis virus	2018-05-02		.txt	text/plain	6872	378	55	To study the roles of hypervariable regions (HVRs) in receptor-binding subunit S1 of the spike protein, we manipulated the genome of the IBV Beaudette strain using a reverse genetics system to construct seven recombinant strains by separately or simultaneously replacing the three HVRs of the Beaudette strain with the corresponding fragments from a QX-like nephropathogenic isolate ck/CH/LDL/091022 from China. We could not detect the replication with ck/CH/ LDL/091022 in Vero cells, so the neutralization tests were performed in 9-day-old SPF embryonated eggs to confirm whether the serotypes of the recombinant IBVs belonged to ck/CH/LDL/091022. Viral antigen was observed in Vero cells infected with the Beaudette strain and the seven recombinant IBVs (Fig. 1b) . S1 gene sequencing results confirmed that the heterogenous HVRs were stably maintained in the recombinant IBVs (Sup Fig. 1) , and no additional mutations were detected in the S protein after three passages in cells or eggs.	./cache/cord-263178-lvxxdvas.txt	./txt/cord-263178-lvxxdvas.txt