TABLE 1.

Amino acid variation of PPE18 among 122 study strains collected in Arkansas from 1996 to 2000^a

Amino acid sequence variant	No. of nsSNPs	No. of other amino acid changes (no. of amino acids, location)b			No. of strains (%)	Genetic group of affected strains
		Insertion	Deletion	Frameshiftc
H37Rv type	0				90 (73.8)
1	1				5 (4.1)	1
2	1				3 (2.5)	2
3	4				4 (3.3)	1
4	3				2 (1.6)	1
5	36	1 (4, 294)	1 (1, 274)	1 (3, 221-223)	1 (0.8)	2
6	7				1 (0.8)	2
7	3				1 (0.8)	2
8	1	1 (4, 294)			1 (0.8)	3
9	2				1 (0.8)	2
10	31	1 (4, 294)	1 (1, 274)	1 (3, 221-223)	1 (0.8)	3
11			1 (18, 17-34)		2 (1.6)	2
12	11				1 (0.8)	2
13	6				1 (0.8)	3
14	31	1 (4, 294)			1 (0.8)	3
15		1 (2, 162)			1 (0.8)	2
16	35		1 (1, 274)	1 (3, 221-223)	1 (0.8)	1
17	9				1 (0.8)	1
18			1 (2, 161-162)		1 (0.8)	2
19d	13				1 (0.8)	2
20	4				1 (0.8)	2
21	3				1 (0.8)	1

^aThe amino acid variants are described based on the number of nsSNPs, the in/dels, and the principal genetic group.

^bin/dels are described based on the number of amino acids affected and the location in the amino acid sequence, which in H37Rv is 391 amino acids long.

^cTwo consecutive frameshifts were found in the same three strains. An insertion of a guanine at bp 659 within the gene, occurring with deletion of a guanine at bp 669, caused the frameshift to be reverted and ultimately affected three amino acids.

^dA codon change at position 155 from UAC to UAA resulted in an amino acid change from tyrosine to termination. The remaining 12 nsSNPs shown occur downstream.