Sequence variation in the circumsporozoite protein gene of Plasmodium vivax appears to be regionally biased.

We have sequenced the circumsporozoite protein gene from 16 isolates from China, the Philippines, Papua New Guinea and the Solomon Islands. We found very limited polymorphisms in the non-repetitive regions of the circumsporozoite gene from these isolates. All samples from China contained a 36-base insert 3' to the repeats previously seen only in a North Korean isolate. Limited variation was found in the repeat regions, which allowed these and previously sequenced isolates to be classified into groups based on repeat structure. These groupings also correlate with the geographical origin of the isolates.