Table S1.

Chemical shifts observed in ¹³C spectra of purified de–O-acetylated Vi antigen

Vi-CPS sample	δC, ppm	C1	C2	C3	C4	C5	C6	NAc (Me)	NAc (CO2)
	Predicted	98.95	51.35	68.44	78.89	72.59	175.87	22.91	175.43
E. coli [viaB]	Observed	99.65	50.71	67.88	79.05	72.49	176.21	23.63	174.95
E. coli [viaBΔvexE]	Observed	99.39	50.56	68.01	78.78	72.61	176.06	23.55	175.57
S. Typhi	Observed	99.71	50.69	67.53	78.98	72.11	176.16	23.55	174.06
S. Typhi ΔvexE	Observed	99.68	50.72	67.80	79.04	72.54	176.23	23.61	174.73