Shurson Gerald C, Ramirez-Camba Christian D, Urriola Pedro E, Schroeder Declan C
Department of Animal Science, College of Food, Agricultural and Natural Resource Sciences, University of Minnesota, St. Paul, MN, United States.
Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul, MN, United States.
Front Vet Sci. 2024 Nov 27;11:1498977. doi: 10.3389/fvets.2024.1498977. eCollection 2024.
Prevention of transmission of African swine fever virus (ASFV) through contaminated feed ingredients and complete feed is an important component of biosecurity protocols for global feed supply chains. Use of extended storage times for feed ingredients has become a popular and emerging mitigation strategy that may allow partial inactivation of ASFV before manufacturing swine feeds. However, the effectiveness of this strategy is unclear because limited studies have been conducted using diverse methodologies and insufficiently sensitive measures of virus viability of only a few types of feed matrices. Therefore, interpretation of results from these studies has made providing prudent recommendations difficult. Furthermore, although a few studies have shown that feed is a plausible route of transmission of ASFV to pigs, there are conflicting findings on the infectivity of ASFV that may be present in feed, which may be related to the extent that ASFV is degraded in the pig's digestive system after it is consumed. Therefore, the objectives of this study were to use a surrogate ASFV-like algal virus (; EhV) to determine stability in corn- and soybean-based feed ingredients and complete feed during a 120-day storage period at temperatures up to 34°C, and EhV survival in various feed matrices during three stages of an digestion process. Results indicated that inoculating corn- and soybean-based feed ingredients and complete feed with EhV and storing them at 4°C, 24°C, or 34°C for up to 120 days did not result in the complete inactivation of EhV in any of these matrices. Because EhV has similar environmental and thermal resilience to ASFV, these results indicate that both viruses can maintain viability in various feed matrices during long-term storage and suggest that extending storage time up to 120 days is not an effective mitigation practice against ASFV. We also determined that between approximately 5- to more than 7-log (99.999 to 99.99999%) reductions in EhV in various feed matrices occur during the entire digestion and fermentation process. These reductions appear to be correlated with the chemical composition of the matrices, potentially explaining inconsistencies in ASFV infection when pigs consume infectious doses of contaminated feed.
预防非洲猪瘟病毒（ASFV）通过受污染的饲料原料和全价饲料传播是全球饲料供应链生物安全协议的重要组成部分。延长饲料原料的储存时间已成为一种流行且新兴的缓解策略，这可能会使ASFV在生产猪饲料之前部分失活。然而，由于仅使用了多种方法对少数几种饲料基质进行病毒活力研究且灵敏度不足，因此该策略的有效性尚不清楚。所以，对这些研究结果的解读使得难以给出谨慎的建议。此外，尽管一些研究表明饲料是ASFV传播给猪的一种可能途径，但关于饲料中可能存在的ASFV的传染性存在相互矛盾的研究结果，这可能与ASFV在猪食用后在消化系统中的降解程度有关。因此，本研究的目的是使用一种替代的ASFV样藻类病毒（EhV）来确定其在基于玉米和大豆的饲料原料以及全价饲料中，在高达34°C的温度下储存120天期间的稳定性，以及在消化过程的三个阶段中EhV在各种饲料基质中的存活情况。结果表明，用EhV接种基于玉米和大豆的饲料原料以及全价饲料，并在4°C、24°C或34°C下储存长达120天，在这些基质中的任何一种中都没有导致EhV完全失活。由于EhV与ASFV具有相似的环境和热弹性，这些结果表明两种病毒在长期储存期间都能在各种饲料基质中保持活力，并表明将储存时间延长至120天不是针对ASFV的有效缓解措施。我们还确定，在整个消化和发酵过程中，各种饲料基质中的EhV减少了约5至超过7个对数（99.999%至99.99999%）。这些减少似乎与基质的化学成分相关，这可能解释了猪食用感染剂量的受污染饲料时ASFV感染的不一致性。
