- Check the primer design using computer software.
- Optimize the annealing temperature in a 1-2°C step.
- A primer concentration of 0.2 μM is satisfactory for most PCR reactions. However, sensitivity and yield of RT-PCR reactions can be improved by increasing the primer concentration to above 0.5 μM. Lower primer concentration between 0.07 μM to 0.2 μM may improve specificity.
- Increase cycling numbers up to 45 cycles.
- Do a manual hot-start.
- Use thin-wall 0.2 ml PCR tubes.
- Try a touch-down PCR protocol (4).