The sWGA method was performed on genomic DNA from unfiltered samples according to published protocols [9 (link)]. The sWGA reaction was performed in 0.2 mL PCR-tubes, containing 10 ng of template genomic DNA, 1 × BSA (New England Biolabs), 1 mM dNTPs (New England Biolabs), 2.5 µM of each amplification primer (Additional file 1 : Table S2), 1 × Phi29 reaction buffer (New England Biolabs), 30 units of Phi29 polymerase (New England Biolabs), and molecular biology grade water to reach a final reaction volume of 50 µL. The reaction was carried out on a thermocycler with the following step-down program: 5 min at 35 °C, 10 min at 34 °C, 15 min at 33 °C, 20 min at 32 °C, 30 min at 31 °C, 16 h at 30 °C, then heating for 15 min at 65 °C to inactivate the Phi29 polymerase before cooling to 4 °C. Amplified products were quantified using the Qubit® dsDNA high sensitivity kit (Thermo Fisher Scientific) to determine whether there was at least 500 ng of product for sequencing. Amplified products were cleaned using Agencourt Ampure XP beads (Beckman Coulter) as follows: 1.8 volumes of beads were added to 1 volume of amplified products, briefly mixed, and then incubated for 5 min at room temperature. A magnetic rack was used to capture the DNA binding beads. The DNA binding beads were then washed twice using 200 µL of 80% ethanol and eluted with 60 µL of EB buffer.
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