PTPN13 and microsporidiosis: Loss of pnp‐1 leads to upregulation of the IPR gene expression and provides resistance to Orsay virus and microsporidia infections.[35, 39] Metabolomic analysis showed that pnp‐1 mutants have increased levels of the PNP substrate inosine, as well as decreased levels of the PNP product, hypoxanthine.