Infection of pigs with African swine fever virus via ingestion of stable flies (<i>Stomoxys calcitrans</i>
)

Olesen, Ann Sofie; Lohse, Louise; Hansen, Mette Frimodt; Boklund, Anette; Halasa, Tariq Hisham Beshara; Belsham, Graham J.; Rasmussen, Thomas Bruun; Bøtner, Anette; Bødker, René

doi:10.1111/tbed.12918

Cited by 79 publications

(98 citation statements)

References 14 publications

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“…The sensitivity of this assay is sufficient for ASF diagnosis on farms or in slaughter houses. During the ASFV infection process, blood virus levels can increase to 1 × 10 6 copies/mL in 5-8 days post-infection (dpi) (Olesen et al, 2018). ASFV infections can result in virus levels of up to 1 × 10 9 TCID 50 /mL in the blood (Dixon et al, 2019), indicating that virus genome copies can achieve >1 × 10 9 copies/mL.…”

Section: Discussionmentioning

confidence: 99%

Cas12a-Based On-Site and Rapid Nucleic Acid Detection of African Swine Fever

et al. 2019

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The mortality rate of hemorrhagic African swine fever (ASF), which targets domestic pigs and wild boars is caused by African swine fever virus (ASFV), can reach 100%. Since the first confirmed ASF outbreak in China on 3 August 2018, 156 ASF outbreaks were detected in 32 provinces. About 1,170,000 pigs were culled in order to halt further spread. There is no effective treatment or vaccine for it and the present molecular diagnosis technologies have trade-offs in sensitivity, specificity, cost and speed, and none of them cater perfectly to ASF control. Thus, a technology that overcomes the need for laboratory facilities, is relatively low cost, and rapidly and sensitively detects ASFV would be highly valuable. Here, we describe an RAA-Cas12a-based system that combines recombinase aided amplification (RAA) and CRISPR/Cas12a for ASFV detection. The fluorescence intensity readout of this system detected ASFV p72 gene levels as low as 10 aM. For on-site ASFV detection, lateral-flow strip readout was introduced for the first time in the RAA-Cas12a based system (named CORDS, Cas12abased On-site and Rapid Detection System). We used CORDS to detect target DNA highly specifically using the lateral-flow strip readout and the assay displayed no crossreactivity to other 13 swine viruses including classical swine fever (CSF). CORDS could identify the ASFV DNA target at femtomolar sensitivity in an hour at 37 • C, and only requires an incubator. For ease of use, the reagents of CORDS were lyophilized to three tubes and remained the same sensitivity when stored at 4 • C for at least 7 days. Thus, CORDS provide a rapid, sensitive and easily operable method for ASFV on-site detection. Lyophilized CORDS can withstand long-term transportation and storage, and is ready for field-based applications.

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Section: Discussionmentioning

confidence: 99%

Cas12a-Based On-Site and Rapid Nucleic Acid Detection of African Swine Fever

et al. 2019

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“…The sensitivity of this assay is sufficient for ASF diagnosis on farms or in slaughter houses. During the ASFV infection process, blood virus levels can increase to 1 × 10 6 copies/mL in 5–8 days post-infection (dpi) [18] . ASFV infections can result in virus levels of up to 1 × 10 9 TCID 50 /mL in the blood [4] , indicating that virus genome copies can achieve > 1 × 10 9 copies/mL.…”

Section: Discussionmentioning

confidence: 99%

Cas12a-based on-site and rapid nucleic acid detection of African swine fever

Bai

Lin

et al. 2019

Preprint

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13The mortality rate of hemorrhagic African swine fever (ASF), which targets domestic pigs and is caused 14 by African swine fever virus (ASFV), can reach 100%. ASF has been reported in 25 Chinese provinces 15 since August 2018. There is no effective treatment or vaccine for it and the present molecular diagnosis 16 technologies have trade-offs in sensitivity, specificity, cost and speed, and none of them cater perfectly 17 to ASF control. Thus, a technology that overcomes the need for laboratory facilities, is relatively low 18 cost, and rapidly and sensitively detects ASFV would be highly valuable. Here, we describe an RAA-19 Cas12a-based system that combines recombinase-aided amplification (RAA) and CRISPR/Cas12a for 20 ASFV detection. The fluorescence intensity readout of this system detected ASFV p72 gene levels as 21 low as 10 aM. For on-site ASFV detection, lateral-flow strip readout was introduced for the first time in 22 the RAA-Cas12a based system (named CORDS, Cas12a-based On-site and Rapid Detection System). 23We used CORDS to detect target DNA highly specifically using the lateral-flow strip readout. CORDS 24 could identify the p72 gene at femtomolar sensitivity in an hour at 37°C, and only requires an incubator. 25For ease of use, the regents of CORDS was lyophilized to three tubes and remained the same sensitivity 26 when stored at 4 °C for at least 7 days. Thus, CORDS provides a rapid, sensitive and easily operable 27 method for ASFV on-site detection. Lyophilized CORDS can withstand long-term transportation and 28 storage, and is ready for field applications. 29 30

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“…For potential mechanical arthropod vectors, stable flies, Stomoxys calcitrans , have been shown to be able to maintain and transmit the virus to pigs under experimental conditions (Mellor et al., ) and also to be able to infect pigs through the oral route (Olesen et al., ,b) and other biting flies such as tabanids have also been discussed (Olesen et al., ,b). Even though there is no scientific evidence on the capacity of any mechanical arthropod vectors to transmit ASFV under field conditions to date, a potential role in the epidemiology, and so in the seasonal pattern of the current epidemic, cannot be ignored.…”

Section: Assessmentmentioning

confidence: 99%

Epidemiological analyses of African swine fever in the European Union (November 2017 until November 2018)

Boklund¹,

Cay²,

Depner³

et al. 2018

EFS2

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This update on the African swine fever (ASF) outbreaks in the EU demonstrated that out of all tested wild boar found dead, the proportion of positive samples peaked in winter and summer. For domestic pigs only, a summer peak was evident. Despite the existence of several plausible factors that could result in the observed seasonality, there is no evidence to prove causality. Wild boar density was the most influential risk factor for the occurrence of ASF in wild boar. In the vast majority of introductions in domestic pig holdings, direct contact with infected domestic pigs or wild boar was excluded as the route of introduction. The implementation of emergency measures in the wild boar management zones following a focal ASF introduction was evaluated. As a sole control strategy, intensive hunting around the buffer area might not always be sufficient to eradicate ASF. However, the probability of eradication success is increased after adding quick and safe carcass removal. A wider buffer area leads to a higher success probability; however it implies a larger intensive hunting area and the need for more animals to be hunted. If carcass removal and intensive hunting are effectively implemented, fencing is more useful for delineating zones, rather than adding substantially to control efficacy. However, segments of fencing will be particularly useful in those areas where carcass removal or intensive hunting is difficult to implement. It was not possible to demonstrate an effect of natural barriers on ASF spread. Human‐mediated translocation may override any effect of natural barriers. Recommendations for ASF control in four different epidemiological scenarios are presented.

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Infection of pigs with African swine fever virus via ingestion of stable flies (Stomoxys calcitrans )

Cited by 79 publications

References 14 publications

Cas12a-Based On-Site and Rapid Nucleic Acid Detection of African Swine Fever

Cas12a-Based On-Site and Rapid Nucleic Acid Detection of African Swine Fever

Cas12a-based on-site and rapid nucleic acid detection of African swine fever

Epidemiological analyses of African swine fever in the European Union (November 2017 until November 2018)

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