Cytochrome Oxidase 2 (COX2), β-Tubulin (TUB) and Chitin Synthase Subunit 2 (CHS2) Expression in Pythium insidiosum Thai Strains

This study aimed to investigate the real-time fluctuation of temperature-sensitive gene expression in a Pythium insidiosum growing at human body temperature (37 oC) when it can cause life-threatening disease, whereas its natural habitat is in agricultural water sources with lower temperature. Genes encoding cytochrome oxidase 2 (COX2), β-tubulin (TUB), and chitin synthase subunit 2 (CHS2) were tested for their expression at the infection temperature (37 oC) and natural habitat temperature (27 oC) using real-time RT-PCR. Sixteen strains of P. insidiosum, representing 3 phylogeographic preferences, were analyzed. The subculturing process at 27 oC was repeated at least 2 - 3 cycles. The results showed that at 37 oC, the COX2 was expressed 2.5-fold higher than that of 27 oC (p = 0.0347) while the level of TUB and CHS2 mRNA disclosed indistinguishable profiles. These results suggested that these genes were suitable to be used as housekeeping genes for temperature-susceptible gene expression studies. This work was likely to be the 1st study examining the gene expression levels of the Thai strain of P. insidiosum under thermal stress conditions. Follow-up studies for the COX2 genes may useful to provide valuable insight into the pathogenesis, diagnostic, or therapeutic targets for further investigation.