TABLE 1.

Mutants used in study

Mutant	Virus sense primer (5′-3′)	Reverse-sense primer (5′-3′)	Mutations	Restriction sites
M254-256	GAGTGCGCAAGCAAAA	TTTTGCTTGCGCACTCA	A254	—c
	TTATTACATATGG	AATTATCAGTTCTTGCC	A256
M248-250	GGCAGCAACTGCTAAT	TTAGCAGTTGCTGCCTC	A248	—c
	TTGAGTGAG	TGTTGAGTAATCACC	A250
M216	GGACTATCGATTACAC	ATCGATAGTCCTGCTAG	D216	ClaI 645
	ACTTGTTGGC	GTAATGCAACC
M144-145	GGACTATCGATTGGTG	CCAATCGATAGTCCTTC	I144	ClaI 431
	GTCTTTCAACCCTG	TGTACAACTGAATGG	D145
M62	GGTCTATAATATCGATC	CGATCGATATTATAGAC	S62	ClaI 184
	GTTTTTATAACTGTGC	CAGCTGAAGTTCCAG
M96-97	GGCCCGTTGTATCGATT	CGTAAGAATCGATACA	S96	ClaI 286
	CTTACGATTTTTAATGC	ACGGGCCATAATAGCC	I97
M144-145-216a			I144	ClaI 431
			D145	ClaI 645
			D216
M62-96-97b			S62	ClaI 184
			S96	ClaI 286
			I97

^aObtained by combination of the M144-145 and M216 mutants by standard cloning techniques. 

^bObtained by combination of the M62 and M96-M97 mutants by standard cloning techniques. 

^c—, no restriction endonuclease site was introduced.