primer design for bisulphite treated DNA - (Nov/18/2004 )

Hi, pcrman; why the forward primer is designed in such a way that it won't be complement to either strand (sense or antisense) after bisulphite conversion? e.g
(example from Nucleic acids research 1994,22:2995)

original strand: 5' ----TCTA GAG TCCC (Antisense:3'---AGAT CTC AGGG 5')
primer : 5' ----TTTA GAG T TTT

Thanks!

Before PCR, the DNA has to be modified using sodium bisulfite to convert unmethylated C to U.

original strand: 5' ----TCTA GAG TCCC [C]GT
modified strand 5'---- TUTA GAG TUUU CGT
primer : 5' ----TTTA GAG T TTT