Table 1. Virus shedding in 3 alpacas infected with MERS-Cov, as measured by virus isolation and real-time PCR for each sample day*.
| Dpi | Cycle threshold value (virus isolation result)†‡ |
No. positive/no. tested |
||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Deep nasal swab sample |
Oral swab sample |
Superficial nasal swab sample |
||||||||||||
| Alpaca 1 | Alpaca 2 | Alpaca 3 | Alpaca 1 | Alpaca 2 | Alpaca 3 | Alpaca 1 | Alpaca 2 | Alpaca 3 | Real-time PCR | Virus isolation | ||||
| 0 | U (–) | U (–) | U (–) | U (–) | 40.8 (–) | U (–) | U (–) | U (–) | U (–) | 0/3 | 0/3 | |||
| 3 | 33.4 (+) | 29.0 (–) | U (–) | 34.2 (–) | 31.7 (–) | 42.3 (–) | 35.4 (–) | 40.7 (–) | U (–) | 2/3 | 1/3 | |||
| 5 | 34.9 (–) | 33.5 (–) | 34.2 (–) | 32.0 (–) | 35.4 (–) | 32.0 (+) | 35.0 (–) | 33.0 (–) | 32.5 (–) | 3/3 | 1/3 | |||
| 7 | 29.4 (+) | 18.2 (–) | 31.4 (+) | 32.7 (–) | 30.1 (+) | 28.3 (+) | 31.9 (–) | 28.5 (+) | 38.6 (+) | 3/3 | 3/3 | |||
| 10 | 41.0 (–) | 37.5 (+) | U (–) | 41.3 (–) | 38.0 (–) | 30.5 (+) | 39.9 (–) | 36.0 (+) | U (–) | 3/3 | 2/3 | |||
| 12 | 42.0 (–) | 36.4 (–) | U (–) | U (–) | U (–) | 37.3 (+) | 42.0 (–) | 39.5 (+) | U (–) | 2/3 | 2/3 | |||
| 14 | U (–) | 42.2 (–) | U (–) | 43.0 (–) | 44.0 (–) | 43.0 (–) | U (–) | U (–) | U (–) | 0/3 | 0/3 | |||
| 21 | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | 0/3 | 0/3 | |||
| 24 | U (–) | U (–) | U (–) | 40.8 (–) | U (–) | U (–) | U (–) | 43.2 (–) | U (–) | 0/3 | 0/3 | |||
| 26 | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | 0/3 | 0/3 | |||
| 28 | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | 0/3 | 0/3 | |||
| 31 | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | 0/3 | 0/3 | |||
| 33 | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | U (–) | 43.1 (–) | U (–) | 0/3 | 0/3 | |||
| 35§ | U (–) | NA | U (–) | U (–) | NA | U (–) | U (–) | NA | U (–) | 0/2 | 0/2 | |||
*Bold indicates positive results (cycle threshold <40). Gray shading indicates that >1 animal was positive for the sample collected on that day. Dpi, day postinfection for challenge (initial infection); MERS-CoV, Middle East respiratory syndrome coronavirus; NA, not available; U, undetermined; –, negative; +, positive. †Real-time PCR cycle threshold values are an average of the duplicates, except when 1 result was undetermined; then, only the single numeric value is shown. ‡The starting dilution was 1:10; the threshold for a positive result was a dilution of >1:20. §Alpaca 2 was euthanized at day 33, leaving only 2 animals in the study at day 35.