Virus viability in spiked swine bone marrow tissue during above‐ground burial method and under in vitro conditions

Abstract

The emergence of high consequence animal diseases usually requires managing significant mortality. A desirable aspect of any carcass management method is the ability to contain and inactivate the target pathogen. The above‐ground burial (AGB) technique was recently developed and proposed as an alternative carcass management method. Here, we investigate the tenacity of swinepox virus (SwPV), as a surrogate model for African swine fever virus (ASFV) in swine carcasses during the AGB process. For this, SwPV was inoculated intrafemorally in 90 adult swine carcasses, which were subsequently disposed under AGB conditions. Bone marrow samples were recovered periodically throughout 12 months and virus viability was assessed by virus isolation (VI), whereas the presence of SwPV DNA was evaluated by quantitative polymerase chain reaction (qPCR). Additionally, an in vitro study assessed the inactivation rate of SwPV, Senecavirus A (SVA), and bovine viral diarrhoea virus (BVDV). Viral suspensions were mixed with bone marrow material and maintained at 21–23°C for 30 days. Virus viability was assessed by VI and viral titration. In the field study, SwPV remained viable only in 11 (55%) bone marrow samples collected on day 7; only viral DNA (and not infectivity) was detected afterwards. SwPV inactivation was estimated to have occurred by day 11. The in vitro testing revealed a variable tenacity of the studied viruses. The viability period was estimated in 28, 80, and 118 days, respectively, for BVDV, SwPV, and SVA. Overall, these findings indicate that the AGB technique was effective in quickly inactivating SwPV. Additionally, the SwPV inactivation rate is comparable to ASFV under field studies and poses a potential model for preliminary ASFV inactivation studies with reduced biosecurity requirements. Moreover, this study contributes to understanding the inactivation kinetics of viruses under specific conditions, which is critical when designing and applying countermeasures in case of biosecurity breaches in sites managing animal mortality.

Viability of African Swine Fever Virus with the Shallow Burial with Carbon Carcass Disposal Method

“…However, the temperatures obtained in the study were still higher than those achieved in a previous study conducted by Ebling et al [21] on SBC. In our study, temperatures above 40 • C were maintained for more than 3 weeks in a burial pit, while temperatures obtained in the study of Ebling et al [21] were less than 37 • C throughout the experiment. On the contrary, air temperatures recorded in this study were lower than those observed in the study of Ebling et al [21] (Figure 5).…”

“…However, the survival of the PPRv in sheep carcasses was not investigated [23]. Ebling et al [21] determined the viability of Swinepox virus (SPv) in bone marrow during SBC on day 7, 14, 21, 28, and around months 2, 3, 6, and 12 post-burial. Although the SPv DNA was detected in 93% of 160 bone marrow samples, the viable virus was only recovered from 11 (55%) bone marrow samples collected on day 7.…”

“…However, there are still some concerns about composting related to the escape of pathogens and/or the release of odor from compost piles, as the carbon layer covering the compost piles can be easily disturbed by insects, scavengers, rats, and other animals. Heavy rain and flooding may also affect the stability of compost piles, thereby exposing animal carcasses to the environment [21]. In Vietnam, a number of infected pigs have been illegally thrown into inappropriate places such as rivers, lakes, and roadsides during the ASF outbreak in 2019, possibly due to the lack of convenient and economical disposal methods [22].…”

“…SBC has been implemented successfully at several sites within the United States and abroad [11,23]. This method has also been shown to be capable of inactivating several pathogens including the Seneca Valley virus and Swine Pox virus [21]. The aim of the present study was to investigate the viability of ASFv in swine carcasses disposed of with SBC.…”

Evaluation of Ultraviolet Type C Radiation in Inactivating Relevant Veterinary Viruses on Experimentally Contaminated Surfaces

“…BVDV belongs to the Pestivirus genus in the family. BVDV has been used as CSFV surrogate in previous viability studies [17][18][19]. Treatment of polystyrene surface spiked with BVDV resulted in over 5 log10 titer reduction.…”