科研之友
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摘要
The aims of this study were to provide a cost-effective and valuable method for evaluating drug efficacy against Cryptosporidium parvum using a quantitative SYBR Green real-time PCR (qPCR) and to assess the efficacy of adenosine analogues as drug templates. C. parvum HNJ-1 strain growing in human ileocaecal adenocarcinoma cells was employed as an in vitro culture system. To normalize the DNA extraction efficiency, a specific plasmid was added to each sample before DNA purification; the genomic DNA of infected cells was quantified by qPCR using specific primers to confirm drug efficacy and cytotoxicity. To determine the mechanism of action, enzymatic inhibition analyses were conducted using C. parvum S-adenosyl-l-homocysteine hydrolase (CpSAHH) recombinant protein. The dose-dependent growth inhibition of C. parvum was confirmed; 50% effective concentrations of neplanocin A (NPA) and 2-fluoroadenosine (2FA) were 139 mu M and 0.842 mu M, respectively. Cytotoxicity evaluation showed that the 50% growth inhibition concentration of 2FA was 1.18 mu M; NPA did not exhibit any cytotoxicity up to 200 mu M. The screening system revealed the specific but marginal efficacy of NPA and showed 2FA to be cytotoxic. Recombinant CpSAHH inhibition analyses showed that NPA competitively inhibited CpSAHH activity (K(i) = 0.395 mu M), whereas 2FA did not. This novel qPCR system confirmed not only drug efficacy against C. parvum but also cytotoxicity to host cells. Moreover, since the SYBR Green method is cost effective, it could therefore be used in a wide variety of clinical and research-oriented applications of Cryptosporidium analysis.
- 出版日期2011-3
