Suchergebnisse

African swine fever (ASF) has persisted in Eastern Europe since 2007, and two endemic zones have been identified in the central and southern parts of the Russian Federation. Moderate- to low-virulent ASF virus isolates are known to circulate in endemic ASF-affected regions. To improve our knowledge of virus transmission in animals recovered from ASF virus infection, an experimental in vivo study was carried out. Four domestic pigs were inoculated with the NH/P68 ASF virus, previously characterized to develop a chronic form of ASF. Two additional in-contact pigs were introduced at 72 days post-inoculation (dpi) in the same box for virus exposure. The inoculated pigs developed a mild form of the disease, and the virus was isolated from tissues in the inoculated pigs up to 99 dpi (pigs were euthanized at 36, 65, 99 and 134 dpi). In-contact pigs showed mild or no clinical signs, but did become seropositive, and a transient viraemia was detected at 28 days post-exposure (dpe), thereby confirming late virus transmission from the inoculated pigs. Virus transmission to in-contact pigs occurred at four weeks post-exposure, over three months after the primary infection. These results highlight the potential role of survivor pigs in disease maintenance and dissemination in areas where moderate- to low-virulent viruses may be circulating undetected. This study will help design better and more effective control programmes to fight against this disease. ; EU project, ASFORCE Targeted Research Effort on African Swine Fever (KBBE.2012.1.3-02, 311931) and the European Union Reference laboratory for ASF (grant no UE- LR PPA/03). ; Peer Reviewed

No effcient vaccines exist against African swine fever virus (ASFV), which causes a serious disease in wild boars and domestic pigs that produces great industrial and ecological concerns worldwide. An extensive genetic characterization of the original ASFV stocks used to produce live attenuated vaccine (LAV) prototypes is needed for vaccine biosecurity and control. Here, we sequenced for the first time the Arm/07 stock which was obtained from an infected pig during the Armenia outbreak in 2007, using an improved viral dsDNA purification method together with high coverage analysis. There was unexpected viral heterogeneity within the stock, with two genetically distinct ASFV subpopulations. The first, represented by the Arm/07/CBM/c2 clone, displayed high sequence identity to the updated genotype II Georgia 2007/1, whereas the second (exemplified by clone Arm/07/CBM/c4) displayed a hemadsorbing phenotype and grouped within genotype I based on a central region conserved among all members of this group. Intriguingly, Arm/07/CBM/c4 contained a unique EP402R sequence, produced by a single mutation in the N-terminal region. Importantly, Arm/07/CBM/c4 showed in vitro features of attenuated strains regarding innate immune response pathway. Both Arm/07/CBM/c2 and c4 represent well-characterized viral clones, useful for different molecular and virus-host interaction studies, including virulence studies and vaccine development ; European Union reference laboratory for ASF (grant no. UE-1 LR PPA/03) and by the INIA project RTA2015-00033-C02-01

African swine fever (ASF) is a complex disease of swine, caused by a large DNA virus belonging to the family Asfarviridae. The disease shows variable clinical signs, with high case fatality rates, up to 100%, in the acute forms. ASF is currently present in Africa and Europe where it circulates in different scenarios causing a high socio-economic impact. In most affected regions, control has not been effective in part due to lack of a vaccine. The availability of an effective and safe ASFV vaccines would support and enforce control–eradication strategies. Therefore, work leading to the rational development of protective ASF vaccines is a high priority. Several factors have hindered vaccine development, including the complexity of the ASF virus particle and the large number of proteins encoded by its genome. Many of these virus proteins inhibit the host's immune system thus facilitating virus replication and persistence. We review previous work aimed at understanding ASFV–host interactions, including mechanisms of protective immunity, and approaches for vaccine development. These include live attenuated vaccines, and "subunit" vaccines, based on DNA, proteins, or virus vectors. In the shorter to medium term, live attenuated vaccines are the most promising and best positioned candidates. Gaps and future research directions are evaluated. ; This review have been promoted and supported by European Commision Directorate-General SANTE, Health and Food Safety, throughout the European Union Reference Laboratory Grant 2016–2017. We thank Pippa Hawes, for providing Electron Microscopy ; We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI).

There is no public supplementary material available. There is no public supplementary material available. ; African swine fever (ASF) is a complex disease of swine, caused by a large DNA virus belonging to the family Asfarviridae. The disease shows variable clinical signs, with high case fatality rates, up to 100%, in the acute forms. ASF is currently present in Africa and Europe where it circulates in different scenarios causing a high socio-economic impact. In most affected regions, control has not been effective in part due to lack of a vaccine. The availability of an effective and safe ASFV vaccines would support and enforce control-eradication strategies. Therefore, work leading to the rational development of protective ASF vaccines is a high priority. Several factors have hindered vaccine development, including the complexity of the ASF virus particle and the large number of proteins encoded by its genome. Many of these virus proteins inhibit the host's immune system thus facilitating virus replication and persistence. We review previous work aimed at understanding ASFV-host interactions, including mechanisms of protective immunity, and approaches for vaccine development. These include live attenuated vaccines, and "subunit" vaccines, based on DNA, proteins, or virus vectors. In the shorter to medium term, live attenuated vaccines are the most promising and best positioned candidates. Gaps and future research directions are evaluated. ; European Commision Directorate-General SANTE "Health and Food Safety"; European Union Reference Laboratory Grant 2016–2017. ; info:eu-repo/semantics/publishedVersion

African swine fever (ASF) has become the major threat for the global swine industry. Furthermore, the epidemiological situation of African swine fever virus (ASFV) in some endemic regions of Sub-Saharan Africa is worse than ever, with multiple virus strains and genotypes currently circulating in a given area. Despite the recent advances on ASF vaccine development, there are no commercial vaccines yet, and most of the promising vaccine prototypes available today have been specifically designed to fight the genotype II strains currently circulating in Europe, Asia, and Oceania. Previous results from our laboratory have demonstrated the ability of BA71∆CD2, a recombinant LAV lacking CD2v, to confer protection against homologous (BA71) and heterologous genotype I (E75) and genotype II (Georgia2007/01) ASFV strains, both belonging to same clade (clade C). Here, we extend these results using BA71∆CD2 as a tool trying to understand ASFV cross-protection, using phylogenetically distant ASFV strains. We first observed that five out of six (83.3%) of the pigs immunized once with 106 PFU of BA71∆CD2 survived the tick-bite challenge using Ornithodoros sp. soft ticks naturally infected with RSA/11/2017 strain (genotype XIX, clade D). Second, only two out of six (33.3%) survived the challenge with Ken06.Bus (genotype IX, clade A), which is phylogenetically more distant to BA71∆CD2 than the RSA/11/2017 strain. On the other hand, homologous prime-boosting with BA71∆CD2 only improved the survival rate to 50% after Ken06.Bus challenge, all suffering mild ASF-compatible clinical signs, while 100% of the pigs immunized with BA71∆CD2 and boosted with the parental BA71 virulent strain survived the lethal challenge with Ken06.Bus, without almost no clinical signs of the disease. Our results confirm that cross-protection is a multifactorial phenomenon that not only depends on sequence similarity. We believe that understanding this complex phenomenon will be useful for designing future vaccines for ASF-endemic areas. ; Ministerio de Ciencia, Innovación y Universidades from the Spanish Government (grant references: AGL2016-78160-C2-1-R, PID2019-107616RB-I00) and with additional support from CERCA (Generalitat de Catalunya)