UP REGULATION OF UBIQUITIN C-TERMINAL HYDROLASE IN THE RESPONSE OF THE MOSQUITO ANOPHELES STEPHENS TO PLASMODIUM YOELII INFECTION

Abstract The isolation and study of genes that are differentially expressed in malaria-infected mosquitoes is important for the elucidation of basic molecular mechanisms underlying vector-parasite interactions. When screening against a previously established cDNAs pool representing specifically expressed genes in the mosquito Anopheles stephemi infected by Plasnwdium γoelii , it was found that one of these encodes a protein with extensive sequence similarity to the Drosophila melarwgaster ubiquitin C-terminal hydrolase (UCTH). Similarity alignment showed that the fragment is 89% identical at amino acid level to the corresponding region of the known An. gambiae EST sequence, as well as 63 % identical to that of both the fruittly and human sequence. Virtual Northern blot expression dynamics of the gene indicated that it was up-regulated significantly in the mosquito at least 1–7 days post-infection, consistent with the critical transition stages of midgut invasion and relocation of sporozoites from the oocysts to the salivary glands during parasite development. Rather little is known about the role of the ubiquitin pathway in the activation of the mosquito innate immune system. The results indicate that the gene is related to malaria infection in mosquito. The cloning and expression profile analysis of AsUCTH enables us to make predictions as to the roles it may play during malaria infection.