Table 1.

Mutations in the M41-CK and Beau-R S gene following passaging in the presence of trypsin.

Sample	Cell Type	Treatment (Trypsin Concentration)	Original Sequence	Mutation	aa Position within S Sequence
M41-CK	Vero	2 µg/mL	R	I	435
M41-CK	Vero	2 µg/mL	T	S	595
Beau-R	Vero	2 µg/mL	V	N	50
M41-CK	CK	UT	N	L	617
M41-CK	CK	0.2 µg/mL	N	L	617
M41-CK	CK	0.5 µg/mL	N	L	617
M41-CK	CK	1.0 µg/mL	N	L	617

Amino acids (aa) are numbered from the start codon of the S protein in each IBV strain.