secondary piRNA processing

A process leading to the generation of a functional secondary piRNA, involving a self-perpetuating piRNA loop, often called the ping-pong cycle, in which piRNAs are amplified by pairing with complementary transcripts (for example the transposable element mRNA target). In Drosophila, the processing involves the piwi proteins aubergine and Argonaute 3 and in mice, the piwi proteins Piwil2 and Piwil4.