The aim was to establish an effective screening microarray at genus level for Pospiviroid. We analyzed nucleotide sequences from Pospiviroid viroid and designed 19 probes with genus identification characteristics. The standards of these probes included the characters of (i) a GC content between 40 and 60%, (ii) less than 50% of single nucleotide, (iii) less than 4 continuous mononucleotides, and (iv) less than 6 nucleotides in the inner hairpin. We synthesized microarrays by using these probes on glass slides. The validation results of microarray probes show effective signals from chrysanthemum stunt viroid and tomato planta macho viroid standard samples hybridization. The sensitivity results show that the microarray detected 200 pg/microL of total RNA. The microarray can be used to screen Pospiviroid viroid.
Base Composition ; Base Sequence ; Microarray Analysis ; Nucleic Acid Hybridization ; Plant Diseases ; virology ; Plant Viruses ; classification ; RNA ; Viroids ; classification

Objective To establish a magnetic nanoparticles separation-based quantitative real-time PCR(RT-PCR)assay for fast and accurate detection of Plasmodium falciparum and providing a technical support for improving the control and preven-tion of imported malaria. Methods According to the conserved sequences of the P. falciparum genome 18SrRNA,the species-specific primers and probe were designed and synthetized. The RT-PCR was established by constructing the plasmid standard , fitting the standard curve and using magnetic nanoparticles separation. The sensitivity and specificity of the assay were evaluat-ed. Results The relationship between the threshold cycle(Ct)and logarithm of initial templates copies was linear over a range of 2.5×101 to 2.5×108 copies/μl(R2=0.999). Among 13 subjects of entry frontier,a P. falciparum carrier with low load was de-tected by using the assay and none was detected with the conventional examinations(microscopic examinations and rapid tests). Conclusion This assay shows a high sensitivity in detection of P. falciparum,with rapid and accurate characteristics,and is especially useful in diagnosis of P. falciparum infectors with low parasitaemia at entry-exit frontier ports.