In some cases, PCR and Sanger sequencing was used to confirm Virochip and deep sequencing calls and to recover additional sequence. Primer sequences are listed in Table S1 . PCR conditions were: 95uC for 2 minutes, 35 cycles of 95uC for 30 seconds, 50-60uC for 30 seconds (primer dependent), 72uC for 1 minute, and 72uC for 2 minutes. PCR products were sizeselected on an agarose gel, purified with the Purelink gel extraction kit (Invitrogen), cloned, and Sanger sequenced.