Early and Rapid Diagnosis and Control of Transboundary Animal Diseases — Phase II: African Swine Fever

Summary

African Swine Fever (ASF) is a highly fatal pig disease rapidly spreading through Africa and into Europe. Control measures are poorly understood. Thus, R&D will focus on improved and rapid detection platforms and the use of effective prophylactic control strategies.

Background and Situation Analysis

African Swine Fever (ASF) is a severe contagious viral disease of domestic pigs and wild boars with a mortality rate that can be as high as 100%. It can be considered as a prototype of transboundary animal diseases (TAD) that crosses borders through both domestic and wildlife animal movements with transmission from animal to animal either indirectly through a vector carrier (tick), by direct contacts between a susceptible and a sick animal or by contact with infected animal products or contaminated objects. The later form of transmission is certainly the most feared since it is at the origin of all outbreaks that are distant from the source of the virus. ASF is endemic in sub Saharan Africa with major outbreaks occurring intermittently causing widespread losses in pig farms. The initial outbreak of ASF in the Caucasian region in 2007, with consequent spread towards the Russian Federation and Belorussia is a clear example of transmission through infected animal products. Due to the potential of creating during an outbreak an infected tick population at the new site, the risk of contaminating an area for many years is high. As culling presents currently the only viable solution of at least stopping the disease spread the economic consequences are dramatic. Consequently the veterinary services are challenged to perform rapid diagnostic confirmation to halt the disease or prevent further outbreaks.

In absence of any useful vaccine and treatment, the early detection of the disease followed by rapid enforcement of control measures remains the only approach for the management of ASF. These strategies involve financial inputs which are not affordable by most of the developing countries. The CRP will aim to develop and validate rapid and field oriented diagnostic tests for ASF virus and promote technology transfer to IAEA Member States to foster the implementation of new nuclear-based diagnostic tests. In parallel the development of an experimental irradiated ASF vaccine including test trails in MS will be carried out to improve the understanding of the immune response to infection and protection. Molecular epidemiology will help describing the expansion patterns of the virus related to its changing genome and pathogenicity factors. Finally sanitary measures will be evaluated to prevent farms from becoming contaminated.

This CRP is in response to MS requests and needs; ASF is a priority disease specifically for OIE, FAO, AU-IBAR and EU. NAFA earned an international reputation for their science driven approaches for controlling TAD's. The capacity in developing appropriate nuclear based diagnostic tools and their validation is widely acknowledged. The current evaluation of irradiation applied for vaccine production (CRP D32029) holds promise to prepare a "vaccine" which at least achieves a partial protection allowing further studies into the so far too complex immunology of the disease. Molecular studies employing whole genome sequencing will for the first time provide the genetic background information needed to address immuno-pathological phenomena and support the development of more specific diagnostic tools based on the recently introduced isothermal amplification techniques applicable to a wide variety of sample matrixes. The combined results of this CRP will provide a novel tool set for researchers, veterinarians and farmers to prevent, diagnose and control the spread of this ever expanding TAD.

Nuclear Component

The nuclear components exploited in this CRP are the,

  • Irradiation attenuation/inactivation of ASF virus for immunological studies and as a potential vaccine candidate.
  • Gene sequencing techniques employing isotope labelled nucleotides for single nucleotide analysis.
  • Protein blotting techniques for the evaluation of immuno-predominant epitopes (Western Blot).
  • Irradiation for the production of reference materials employed in ring trials for the harmonisation of diagnostic approaches.

CRP Overall Objective

To extend our understanding and evaluate control tools and procedures to limit the spread of ASF or even revert it.

Specific Objectives

Improved control of ASF through new diagnostic and preventive approaches.

Expected Research Outcomes

  • Whole genome sequence data allows designing improved diagnostic tests and candidate vaccines and supports molecular epidemiology.
  • Evaluation of diagnostic tests (serology/ molecular amplification) allows their definition of fitness for purpose.
  • Harmonized reporting manual for ASF field strains regarding their pathology and spreading characteristics.
  • Experimental vaccine design tested in pigs.
  • Improved control of ASF outbreaks due to sanitary measures.

Expected Research Outputs

  • Whole genome sequence data generated and disseminated for 20 strains.
  • Provision of a manual describing diagnostic tests for ASF and their fitness for purpose.
  • Patho-epidemiological manual developed for the classification of ASF field strains.
  • Experimental vaccines prepared and tested.
  • Manual of sanitary measures to contain ASF in different environmental settings.