[Optimization of HIV diagnosis using the RT-PCR (gag) method with various dilutions of cDNA and MgCl2 molarity].

Lack of optimum conditions for PCR can lead to absence of desired PCR products, undefined multiplication and appearance of unwanted products. So, the use of PCR aiming to generate large amounts of target nucleic acid sequences, may be so called "double-edged sword". The important parameters in optimisation of PCR methodology are annealing temperatures, Mg++ concentration and different dilutions of target sequences. In our optimization experiments of HIV-RT-PCR (GAG) method we used HIV positive plasma specimens for extraction of RNA and production of cDNA by reverse transcriptase. Different cDNA dilution (10(-1)-10(-10)) and MgCl2 molarity (1.25 mM; 1.5 mM; 5.0 mM) we used for first round (GAG1 and GAG4 outer primers) and second round PCR (GAG2 and GAG3 inner primers). Optimal results after 3% NuSieve agarose gel electrophoresis and detection of 413 pb PCR products were obtained with 1.25 mM MgCl2 and cDNA dilution 10(-1) and 10(-2). So the main aim of PCR optimisation is the achievement of optimal primer template binding and primer extension.