bio-primer-design-qpcr-primers

Version Compatibility

Reference examples tested with: BioPython 1.83+, pandas 2.2+, primer3-py 2.0+

Before using code patterns, verify installed versions match. If versions differ:

• Python: pip show <package> then help(module.function) to check signatures

If code throws ImportError, AttributeError, or TypeError, introspect the installed package and adapt the example to match the actual API rather than retrying.

qPCR Primer and Probe Design

Design primers and internal probes for quantitative PCR using primer3-py.

"Design qPCR primers with probe" → Generate primer pairs plus internal TaqMan/molecular beacon probes with constrained Tm and spacing.

• Python: primer3.design_primers(seq_args, global_args) with PRIMER_PICK_INTERNAL_OLIGO=1 (primer3-py)

Required Imports

import primer3
from Bio import SeqIO

Design Primers with TaqMan Probe

sequence = 'ATGCGTACGATCGATCGATCGATCGATCGATCGATCGATCGATCGATCGATCGATCGATCGATCG' * 3

result = primer3.design_primers(
    seq_args={'SEQUENCE_TEMPLATE': sequence},
    global_args={
        'PRIMER_PICK_LEFT_PRIMER': 1,
        'PRIMER_PICK_RIGHT_PRIMER': 1,
        'PRIMER_PICK_INTERNAL_OLIGO': 1,  # Design internal probe
        'PRIMER_PRODUCT_SIZE_RANGE': [[70, 150]],  # Short amplicons for qPCR
        'PRIMER_OPT_TM': 60.0,
        'PRIMER_MIN_TM': 58.0,
        'PRIMER_MAX_TM': 62.0,
        'PRIMER_INTERNAL_OPT_TM': 70.0,  # Probe Tm ~10C higher
        'PRIMER_INTERNAL_MIN_TM': 68.0,
        'PRIMER_INTERNAL_MAX_TM': 72.0,
        'PRIMER_INTERNAL_MIN_SIZE': 18,
        'PRIMER_INTERNAL_OPT_SIZE': 25,
        'PRIMER_INTERNAL_MAX_SIZE': 30,
    }
)

Extract Probe Results

num_returned = result['PRIMER_PAIR_NUM_RETURNED']
print(f'Found {num_returned} primer/probe sets')

for i in range(num_returned):
    left = result[f'PRIMER_LEFT_{i}_SEQUENCE']
    right = result[f'PRIMER_RIGHT_{i}_SEQUENCE']
    probe = result[f'PRIMER_INTERNAL_{i}_SEQUENCE']
    probe_tm = result[f'PRIMER_INTERNAL_{i}_TM']
    left_tm = result[f'PRIMER_LEFT_{i}_TM']
    right_tm = result[f'PRIMER_RIGHT_{i}_TM']
    product_size = result[f'PRIMER_PAIR_{i}_PRODUCT_SIZE']

    print(f'Set {i}:')
    print(f'  Forward: {left} (Tm: {left_tm:.1f}C)')
    print(f'  Reverse: {right} (Tm: {right_tm:.1f}C)')
    print(f'  Probe:   {probe} (Tm: {probe_tm:.1f}C)')
    print(f'  Product: {product_size}bp')