Infectious African Swine Fever Virus Survives in Spray-Dried Porcine Plasma Used as Feed Ingredient
A feed ingredient built from pig blood has now been tied to infectious African swine fever virus in South Korea, and the experimental result was unforgiving. Pigs inoculated with virus-positive spray-dried porcine plasma developed acute fever, rapidly progressive illness, and death within days, while a matching compound feed sample did not produce infection in a small oral-feeding challenge.
The finding is important because ASFV is not a fragile virus. It remains stable in meat and blood for long periods, and that durability creates a plausible route for contamination to persist through processing, transport, and farm storage. In this investigation, the concern was not theoretical contamination detected only by molecular assay. Viable virus was recovered from spleen homogenates after inoculation, proving that the material retained infectious capacity.
Feed Contamination Mapped to an Active Outbreak Chain
Investigators tested 72 spray-dried porcine plasma samples and 219 commercial compound feed samples collected from pig farms involved in ASF outbreaks. ASFV DNA was detected in two SDPP samples on February 19, 2026, with cycle threshold values of 28.48 and 31.18, and in two commercial compound feed samples on February 24, 2026, with Ct values of 35.97 and 37.71. Virus isolation from those original feed materials did not succeed, but the PCR signal was strong enough to justify experimental challenge.
Nine healthy 4-week-old Landrace pigs were divided into three groups of three. One group received an intramuscular inoculation with a 50% suspension of the ASFV-positive SDPP; a second group was fed 200 g of the ASFV-positive compound feed once daily for 30 days; the third served as a negative control. The design separated parenteral exposure from oral ingestion and helped distinguish contamination from infectivity.
Acute Fever, Viremia, and Death After SDPP Inoculation
The SDPP group declared the virus’s pathogenicity quickly. Two pigs developed acute pyrexia at 5 days postchallenge and the third at 6 days postchallenge. Rectal temperatures climbed as high as 41.2°C before death, and the clinical picture sharpened into severe lethargy, anorexia, huddling, and depression.
All three inoculated pigs died. Mean time to death was 8.0 ± 0.8 days postchallenge.
Viremia appeared in whole blood by 4 days postchallenge, and viral shedding was detected through both oral and rectal routes from that point onward. Blood carried higher viral loads than the swab specimens, a pattern consistent with systemic dissemination rather than limited local replication. The compound-feed group and the control group stayed clinically stable and uninfected during the study period.
For field veterinarians and feed regulators, that sequence matters. Fever, hemorrhagic disease, and death followed quickly after exposure to contaminated SDPP, showing how little margin exists once ASFV enters a susceptible pig population.
Necropsy Showed Systemic Hemorrhagic Disease
Necropsy findings in the three dead pigs were consistent with fulminant ASF. Investigators documented severe multiorgan lesions marked by extensive congestion and systemic hemorrhage. The spleen was enlarged and showed severe hemorrhagic infarction, while the mandibular, gastrohepatic, and renal lymph nodes were enlarged, hemorrhagic, and erythematous. ASFV DNA was found in postmortem tissues, and all tissues with gross lesions tested positive.
Those lesions fit the biology of ASFV. The virus targets cells of the monocyte-macrophage lineage, drives inflammatory injury, and disrupts vascular integrity, which helps explain the hemorrhage, organ swelling, and rapid collapse seen in infected pigs.
Genomic Analysis Linked the Isolate to South Korean Strains
Molecular characterization placed the virus within p72 genotype II and identified the IGR-I variant. Sanger sequencing covered the B646L (p72), E183L (p54), and EP402R (CD2v) genes, along with the central variable region of B602L and the I73R/I329L intergenic region. After viable virus was isolated from spleen homogenates, whole-genome sequencing produced ASFV/Korea/SDPP/2026, which shared 99.98% nucleotide identity with ASFV/Korea/pig/Dangjin/2025, a strain detected during a farm outbreak.
The genome also carried structural features already seen in South Korean isolates, including a 706-bp deletion across MGF 110–7L and 285L in the left variable region and a 9-bp insertion in the MGF 110–10L to 110–14L region. Both the Dangjin and SDPP isolates belonged to IGR type I, whereas most previously characterized South Korean isolates had been IGR type II. The phylogenetic tree clustered the SDPP isolate with viruses from affected pig farms and wild boar, pointing toward domestic circulation rather than a separate importation event.
Why the Oral Feeding Arm Stayed Negative
No infection developed in the pigs fed the compound feed, even though the feed had tested positive by PCR. Several explanations fit the data without overstating them. Viral infectivity may have declined during storage at the farm, the oral route may have delivered a dose below the infectious threshold, or feed matrix effects may have reduced bioavailability. Oral exposure to ASFV generally requires a higher viral dose than direct inoculation, so a negative feeding arm does not erase the risk signal attached to the contaminated ingredient.
The small size of the challenge group is the most obvious constraint. With only three pigs per arm, the absence of disease after oral exposure cannot rule out feedborne transmission under different storage conditions, different viral loads, or repeated exposure in the field.
Feed Safety Now Sits Inside ASF Control Strategy
South Korea has already seen ASF move through domestic pig farms, wild boar, and multiple suspected farm-level risk factors. This investigation adds contaminated SDPP to that list as a credible vehicle for transmission. The interval between feed manufacturing and farm outbreaks ranged from 56 to 116 days, and ASFV can remain infectious for more than 100 days at 4°C, leaving enough time for contaminated material to remain viable across the production chain.
The practical implication is straightforward: surveillance cannot stop at animals and vehicles. Porcine blood products and feed ingredients deserve closer scrutiny, especially when they originate from slaughterhouse-derived material with known nutritional and commercial value. Risk management for SDPP now has a clear virologic basis, not just an abstract biosafety rationale.
South Korea’s 2026 outbreak pattern, the genomic match to domestic strains, and the recovery of viable virus from infected pigs all point to one conclusion: contaminated SDPP can carry infectious ASFV into the production system, and feed controls need to account for that possibility.