Abstract
African swine fever (ASF) is an acute viral hemorrhagic disease of domestic swine with mortality rates approaching 100%. Devastating ASF outbreaks and continuing epidemics starting in the Caucasus region and now in the Russian Federation, Europe, China, and other parts of Southeast Asia (2007 to date) highlight its significance. ASF strain Georgia-07 and its derivatives are now endemic in extensive regions of Europe and Asia and are “out of Africa” forever, a situation that poses a grave if not an existential threat to the swine industry worldwide. While our current concern is Georgia-07, other emerging ASFV strains will threaten for the indefinite future. Economic analysis indicates that an ASF outbreak in the U.S. would result in approximately $15 billion USD in losses, assuming the disease is rapidly controlled and the U.S. is able to reenter export markets within two years. ASF’s potential to spread and become endemic in new regions, its rapid and efficient transmission among pigs, and the relative stability of the causative agent ASF virus (ASFV) in the environment all provide significant challenges for disease control. Effective and robust methods, including vaccines for ASF response and recovery, are needed immediately.
Highlights
African swine fever (ASF) is an acute viral hemorrhagic disease of domestic swine with mortality rates approaching 100%
Lack of detectable anti-ASF virus (ASFV) antibodies at the time of challenge in DNAvaccinated and partially protected animals has been interpreted as support for the role of cellular immunity in protection [22,39]
ASF subunit vaccines where only specific protective viral antigens and optimized delivery/vector systems are used to vaccinate the host may improve upon traditional inactivated vaccine approaches and remove safety concerns associated with Live-Attenuated ASF Viruses (LAVs)
Summary
ASFV, the sole member of the Asfarviridae (Asfar, African swine fever, and related viruses), is a large, enveloped genetically complex virus containing a double-stranded. Of potential significance from a vaccine design and a disease control perspective, ASFV appears to establish long-term persistent/latent infections in warthogs and in domestic pigs surviving acute viral infection [8,9,10,11]. Viral DNA can be PCR-amplified from peripheral blood monocytes of pigs persistently infected with ASFV for at least 500 days post-infection [13]. The actual significance of ASFV persistent infection for virus perpetuation and transmission within domestic pig populations remains unclear [14], the detection of ASFV DNA in blood samples collected from clinically normal pigs at slaughter in an ASF endemic region suggests that chronically or persistently infected animals may be responsible for ASF persistence within endemic regions [15,16]. Vaccine development has been hindered by large gaps in knowledge concerning aspects of ASFV infection and immunity, the extent of ASFV strain variation, and the ASFV proteins (protective antigens; (PA)) responsible for inducing protective immune responses in the pig
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