scholarly journals Putative Role of Arthropod Vectors in African Swine Fever Virus Transmission in Relation to Their Bio-Ecological Properties

Viruses ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 778 ◽  
Author(s):  
Sarah I. Bonnet ◽  
Emilie Bouhsira ◽  
Nick De Regge ◽  
Johanna Fite ◽  
Florence Etoré ◽  
...  

African swine fever (ASF) is one of the most important diseases in Suidae due to its significant health and socioeconomic consequences and represents a major threat to the European pig industry, especially in the absence of any available treatment or vaccine. In fact, with its high mortality rate and the subsequent trade restrictions imposed on affected countries, ASF can dramatically disrupt the pig industry in afflicted countries. In September 2018, ASF was unexpectedly identified in wild boars from southern Belgium in the province of Luxembourg, not far from the Franco-Belgian border. The French authorities rapidly commissioned an expert opinion on the risk of ASF introduction and dissemination into metropolitan France. In Europe, the main transmission routes of the virus comprise direct contact between infected and susceptible animals and indirect transmission through contaminated material or feed. However, the seasonality of the disease in some pig farms in Baltic countries, including outbreaks in farms with high biosecurity levels, have led to questions on the possible involvement of arthropods in the transmission of the virus. This review explores the current body of knowledge on the most common arthropod families present in metropolitan France. We examine their potential role in spreading ASF—by active biological or mechanical transmission or by passive transport or ingestion—in relation to their bio-ecological properties. It also highlights the existence of significant gaps in our knowledge on vector ecology in domestic and wild boar environments and in vector competence for ASFV transmission. Filling these gaps is essential to further understanding ASF transmission in order to thus implement appropriate management measures.

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Rémi Pereira De Oliveira ◽  
Evelyne Hutet ◽  
Renaud Lancelot ◽  
Frédéric Paboeuf ◽  
Maxime Duhayon ◽  
...  

Abstract Background Several species of soft ticks in genus Ornithodoros are known vectors and reservoirs of African swine fever virus (ASFV). However, the underlying mechanisms of vector competence for ASFV across Ornithodoros species remain to be fully understood. To that end, this study compared ASFV replication and dissemination as well as virus vertical transmission to descendants between Ornithodorosmoubata, O. erraticus, and O. verrucosus in relation to what is known about the ability of these soft tick species to transmit ASFV to pigs. To mimic the natural situation, a more realistic model was used where soft ticks were exposed to ASFV by allowing them to engorge on viremic pigs. Methods Ornithodoros moubata ticks were infected with the ASFV strains Liv13/33 (genotype I) or Georgia2007/1 (genotype II), O. erraticus with OurT88/1 (genotype I) or Georgia2007/1 (genotype II), and O. verrucosus with Ukr12/Zapo (genotype II), resulting in five different tick–virus pairs. Quantitative PCR (qPCR) assays targeting the VP72 ASFV gene was carried out over several months on crushed ticks to study viral replication kinetics. Viral titration assays were also carried out on crushed ticks 2 months post infection to confirm virus survival in soft ticks. Ticks were dissected. and DNA was individually extracted from the following organs to study ASFV dissemination: intestine, salivary glands, and reproductive organs. DNA extracts from each organ were tested by qPCR. Lastly, larval or first nymph-stage progeny emerging from hatching eggs were tested by qPCR to assess ASFV vertical transmission. Results Comparative analyses revealed higher rates of ASFV replication and dissemination in O. moubata infected with Liv13/33, while the opposite was observed for O. erraticus infected with Georgia2007/1 and for O. verrucosus with Ukr12/Zapo. Intermediate profiles were found for O. moubata infected with Georgia2007/1 and for O. erraticus with OurT88/1. Vertical transmission occurred efficiently in O. moubata infected with Liv13/33, and at very low rates in O. erraticus infected with OurT88/1. Conclusions This study provides molecular data indicating that viral replication and dissemination in Ornithodoros ticks are major mechanisms underlying ASFV horizontal and vertical transmission. However, our results indicate that other determinants beyond viral replication also influence ASFV vector competence. Further research is required to fully understand this process in soft ticks.


2019 ◽  
Vol 19 (7) ◽  
pp. 512-524 ◽  
Author(s):  
Andrew J. Golnar ◽  
Estelle Martin ◽  
Jillian D. Wormington ◽  
Rebekah C. Kading ◽  
Pete D. Teel ◽  
...  

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mariia Nefedeva ◽  
Ilya Titov ◽  
Sodnom Tsybanov ◽  
Alexander Malogolovkin

AbstractThe recombination is one of the most frequently identified drivers of double-stranded DNA viruses evolution. However, the recombination events in African swine fever virus (ASFV) genomes have been poorly annotated. We hypothesize that the genetic determinants of ASFV variability are potential hot-spots for recombination. Here, we analyzed ASFV serotype-specific locus (C-type lectin (EP153R) and CD2v (EP402R)) in order to allocate the recombination breakpoints in these immunologically important proteins and reveal driving forces of virus evolution. The recombinations were found in both proteins, mostly among ASFV strains from East Africa, where multiple virus transmission cycles are notified. The recombination events were essentially associated with the domain organization of proteins. The phylogenetic analysis demonstrated the lack of clonal evolution for African strains which conclusively support the significance of recombinations in the serotype-specific locus. In addition, the signature of adaptive evolution of these two genes, pN/pS > 1, was demonstrated. These results have implications for the interpretation of cross-protection potential between evolutionary distant ASFV strains and strongly suggest that C-type lectin and CD2v may experience substantial selective pressure than previously thought.


2020 ◽  
Vol 64 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Mateusz Fila ◽  
Grzegorz Woźniakowski

AbstractAfrican swine fever (ASF) is an acute viral haemorrhagic disease of pigs and wild boars. It presents a serious threat to pig production worldwide, and since 2007, ASF outbreaks have been recorded in the Caucasus, Eastern Europe, and the Baltic States. In 2014, the disease was detected in Poland. ASF is on the list of notifiable diseases of the World Organisation for Animal Health (OIE). Due to the lack of an available vaccine and treatment, the countermeasures against the disease consist in early detection of the virus in the pig population and control of its spread through the elimination of herds affected by disease outbreaks. Knowledge of the potential vectors of the virus and its persistence in the environment is crucial to prevent further disease spread and to understand the new epidemiology for how it compares to the previous experience in Spain gathered in the 1970s and 1980s.


2020 ◽  
Vol 67 (4) ◽  
pp. 1472-1484 ◽  
Author(s):  
Ann Sofie Olesen ◽  
Graham J. Belsham ◽  
Thomas Bruun Rasmussen ◽  
Louise Lohse ◽  
René Bødker ◽  
...  

2021 ◽  
pp. 405-412
Author(s):  
Armanda Bastos ◽  
Fernando Boinas

Abstract African swine fever (ASF) virus, currently the only recognized DNA arbovirus, is the causative agent of a highly virulent and frequently lethal haemorrhagic fever of pigs and wild boar. The virus is readily transmitted between infected Sus scrofa (wild and domestic), as well as through ingestion of infected pork, fomites and some haematophagous vectors. Although several arthropod species have been evaluated for virus competence, argasids (soft ticks) of the genus Ornithodoros are the only known invertebrates that are reservoirs of the virus. This chapter provides information on ASF virus infection status and vector competence of Ornithodoros tick populations in Africa.


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