Using Phrap Assembly For Recombinining Sequences
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11.5 years ago

What are the best phrap parameters for assembling sequence reads(forward and reverse) in cloned parasite isolates that are known to undergo recombination?

assembly recombination • 2.3k views
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What parasite and what level of recombination?

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I agree with Jarretinha, knowing the scale of recombination would be important to know

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the parasite is Plasmodium falciparum. i do not know exactly what the full scale or recombination is. but let us say high recombination rates among the surface antigens.

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11.0 years ago
Lee Katz ★ 3.1k

I'm not sure if recombination rates have anything to do with it. You've sequenced a locus with two reads (F/R) and want to assemble those reads. Whatever level of recombination, those reads are true data. Just assemble with normal parameters.

phred *.ab1 -sd . -qd . -pd .
phd2fasta forward.phd.1 reverse.phd.1 -os locus.fna -oq locus.fna.qual
phrap locus.fna -ace 2>phrap.err 1>phrap.out
# output is in locus.fna.contigs and locus.fna.contigs.qual


If these forward and reverse sequences do not assemble, consider the possibility that there is some physical obstruction to their overlap. Maybe a recombination event created an insertion between the forward and reverse sequences, such that you need to sequence the insert before you can assemble all sequences. Or, your forward or reverse primer locus was recombined to a different place in the genome. To overcome this obstruction, you may need to primer walk.