HIV gag gene pcr

[saintaditya]

Hi ,
I did a pcr with fresh samples of HIV - subtype C samples . I was usin primers which were slightly dated . SK143 and SK431 primers which are yeilding dual bands on my gel after PCR instead of the 143 bp band their is an additional band of roughly 250 bp . any clues why this is happening and no their isnt any contaminations i have redone the whole thing with the same results. also is their some way to eliminate these additonal bands.

[MrMistery]

Maybe some nucleotides parted from your primers while they got old. This way they will sit in a different place and you could get a result like that

[saintaditya]

That is something that occured to me but the thing is that it gives dual bands only with a few samples . like (50) and not with the other half . any comments on that ??