Research Article

Detection of African Swine Fever Virus in Feed and Feed Mill Environment Following Extended Storage

Table 3

Proportion of qPCR positive and main effects of location on cycle threshold (Ct) and log10 genomic copies/mL of environmental discs for ASFV DNA survival after experimental inoculation of swine feed and subsequent feed batch sequencing.

DayProportion PCR positiveCycle threshold valueLog10 genomic copies/mL§

16/633.83.9
36/634.03.9
76/635.33.6
145/636.73.0
286/633.93.9
606/637.72.9
906/635.53.5
1804/639.32.2

Note: Twenty-seven stainless steel coupons were randomly placed in location (nine coupons in each of three locations of the room) and allowed to collect feed dust produced during manufacture. Stainless steel coupons remained sealed in a secondary container and stored at room temperature (RT) in a locked cabinet. On Day of and 3, 7, 14, 28, 60, 90, and 180 days after feed manufacturing, one sample from each of the three location blocks following RT storage were randomly selected, opened within a BSC, swabbed using a 10 × 10 cm cotton gauze, prepared and analyzed as for ASFV DNA via PCR. Samples that had no detectable ASFV DNA were assigned a Ct value of 45.0. Day: , SEM = 1.98. §Genomic copies/mL of sample processing lysate. Day: , SEM = 0.60.