Volume 25, Number 8—August 2019
Research Letter
Prolonged Zika Virus RNA Detection in Semen of Immunosuppressed Patient
Table
Sample no. | Days after symptom onset | RT-PCR Ct value† | Sequence coverage, %‡ | Average read depth | Sequencing platform§ | Mutations detected | Culture result |
---|---|---|---|---|---|---|---|
1 | 13 | 19 | 99.9 (min depth 2), 88.4 (min depth 40) | 386.9 | MinION | Reference | Frozen sample: unsuccessful |
2 | 46 | 26 | ND | NA | NA | Fresh sample: unsuccessful | |
3 | 167 | Subthreshold | ND | NA | NA | ND | |
4 | 194 | No RNA detected¶ | ND | NA | NA | ND | |
5 | 241 | 31 | Unsuccessful | NA | NA | ND | |
6 | 257 | 34 | 44 (min depth 2), 0 (min depth 40) | 3.3 | MinION | None | Frozen sample: unsuccessful |
7 | 278 | No RNA detected¶ | ND | NA | NA | ND | |
8 | 326 | 26 | 76 (min depth 2), 6 (min depth 40) | 13.2 | MinION | None | Fresh sample: unsuccessful |
9 | 396 | 29 | ND | NA | NA | ND | |
10 | 515 | 24 | 98.1 (min depth 5) | 33.3 | MiSeq | K3272E, Syn2921 | Fresh sample: unsuccessful |
11 | 687 | 39 | ND | NA | NA | ND | |
12 | 941 | 32 | ND | NA | NA | ND |
*Ct, cycle threshold; min, minimum; NA, not applicable; ND, not done; RT-PCR, reverse transcription PCR.
†Before PCR, nucleic acid was extracted from samples 1–7 using the EZ1 Virus Mini Kit (QIAGEN, https://www.qiagen.com). Samples 8–12 were extracted using the MagNA Pure 96 DNA and Viral NA Small Volume Kit (LifeScience-Roche Diagnostics Corporation, https://lifescience.roche.com). Ct values <40 with acceptable amplification curves are interpreted as positive, but results for samples with Ct values >35 are confirmed by re-extraction and repeat PCR in triplicate, where possible.
‡Conservative read-depth thresholds were selected for comparative analyses of the day 13 (sample 1) and day 515 (sample 10) consensus genomes.
§MinION (Oxford Nanopore Technologies, https://nanoporetech.com); MiSeq (Illumina, https://www.illumina.com).
¶Confirmed on reextraction and repeat PCR testing.