Nucleic Acid Sequence-Based Amplification (NASBA) is an isothermal (constant temperature) molecular amplification technique specifically designed to amplify RNA targets. It operates at 41°C without the need for a thermal cycler, making it potentially useful in field settings. The process involves three enzymes: reverse transcriptase, RNase H, and T7 RNA polymerase. It starts with a single-stranded RNA target. A primer containing a T7 promoter sequence binds, and reverse transcriptase creates a complementary DNA (cDNA) strand, forming an RNA-DNA hybrid. RNase H degrades the RNA strand. A second primer binds to the cDNA, and reverse transcriptase extends it to form double-stranded DNA (dsDNA) with a functional T7 promoter. T7 RNA polymerase then recognizes this promoter and produces multiple copies of antisense RNA amplicons. These amplicons can then re-enter the cycle, leading to exponential amplification of the original RNA target. In parasitology, NASBA is particularly valuable for detecting live, viable parasites because it targets labile messenger RNA (mRNA), which degrades quickly in dead organisms. It has been applied to detect viable Cryptosporidium parvum oocysts in water samples, diagnose active malaria (detecting Plasmodium rRNA), and in research for other parasites where distinguishing active infection from past exposure is important.

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Zambia

• Naomi Miselo – 31 pts

• Visual Pathway Lesions
• Positive and Negative Symptoms
• Hallucinations and Delusions
• Antipsychotic Medications
• Emergency: Environmental Emergencies