The health status of pigs plays a major role in the development of ASF – Research

A pig in a healthy state is less at risk

calendar icon September 12, 2022

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3 minutes to read

Recently Research conducted At the Institute of Virology and Immunology (IVI) in Mittelhäusern in Switzerland in collaboration with University of Bern revealed that the health status of pigs plays an important role in the development of the disease caused by the African swine fever virus. These very important findings have been published in the journal PLOS Pathogens and will ultimately contribute to vaccine development.

The complexity of the African swine fever virus (ASF) explains the lack of a safe and effective vaccine. The virus causes fatal hemorrhagic fever in domestic pigs and wild boars. With hundreds of millions of animals infected in Africa, Europe and Asia, this disease has significant social and economic consequences for farmers and the global food industry. For this reason, the Institute of Virology and Immunology (IVI) – the Swiss reference laboratory for the ASF – is investigating the immune responses needed to induce protection in pigs.

A pig in a healthy state is less at risk

The lethal strains of ASF that are currently circulating in Europe, Asia, and the Caribbean are fatal within days regardless of the health status of pigs. Thus, the research aims to investigate immune responses in pigs using attenuated strains of ASF, although in some cases these strains can be fatal.

By infecting pigs with the attenuated strain of ASF, the research groups at IVI and the University of Bern, led by Nicholas Rogli, Sharaf Ben Arfa and Arthur Sommerfeld, discovered that domestic pigs with very high health and health status were milder and shorter. The form of the disease is followed by complete recovery. By contrast, farm pigs with standard traditional health status suffered from long-term disease with a lethality rate of 50%. Analysis of the immune system before and during infection indicates that higher baseline immune activation has important consequences for disease severity and inflammatory responses. According to Sharaf Ben Arfa, veterinarian and immunologist, these differences in baseline activation of the immune system in relation to health status are key factors in determining the development of ASF during infection with an attenuated strain. In conclusion, Nicholas Rogley, veterinarian and virologist, explains that these findings are very important, especially for the development of live attenuated vaccines against ASF and, in general, for our understanding of host-pathogen interactions in hemorrhagic fever.

The importance of basic research

Although Switzerland is currently ASF-free, IVI is studying the distinctive features of the ASF virus strains circulating in Europe. Keeping up to date with the latest findings is vital to ensure effective and safe diagnosis if the disease reaches Switzerland, and to provide the Swiss Veterinary Service with critical information about virological, immunological, clinical and pathological aspects.

A complex and bewildering virus

The ASF virus is large and complex with a genome of more than 160 genes, half of which are (still) unknown. The challenges arise from the basic characteristics of this virus, which infects macrophages and hijacks the immune system. From an empirical point of view, the studies are done on cell and pig cultures, and require a high-containment laboratory such as the one at IVI.

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