Pandemic Hopscotch: from African Swine Fever to COVID-19

Abstract:

African Swine Fever Virus (ASFV) is a dsDNA virus of the family Iridoviridae which causes African Swine Fever (ASF). ASFV is non-infectious in humans, but exceptionally lethal (near 100%) in domesticated pigs. Cases of ASFV have been described globally, and several strains have been sequenced. Despite progress in understanding the basic virology behind ASFV, there is no existing treatment or vaccine. ASFV in pigs causes hemorrhagic fever, afflicting the porcine reticuloendothelial cells. Common symptoms in infected pigs include fever, changes in appetite, vomiting, weakness, and skin rashes. The current procedure for ASF outbreaks is to quarantine and cull infected pigs. In many countries, pork meat is one of the highest consumed protein sources. Pig farms range from small-scale family farms to larger commercial farms, and all are vulnerable in some capacity by ASFV. Food insecurity can result in these areas due to the loss of a vital pork protein source as well as income associated with pig farms. For instance, China was greatly impacted by an ASF outbreak starting in 2018 which had catastrophic effects on the availability of pork. Due to their ongoing ASF epidemic, prices for pork products increased by 78% and China suffered economic losses estimated at $141 billion. With such a loss in food security in China in 2018, alternative sources of proteins became more popular, including access to wildlife game in wet markets. Such markets are associated with zoonotic diseases where pathogens affecting animals are introduced to a naïve human reservoir. An example of this is the ongoing COVID-19 pandemic which resulted from the wet market consumption of bats harboring SARS-CoV-2 virions. Here we describe the design of a tetravalent RNA vaccine that targets key structural proteins implicated in the viral entry of ASFV into porcine host cells. Our design is codon-optimized for Sus scrofa (pig) and checked for porcine anaphylaxis. We hope that our design might one day be field-tested to determine if it elicits a porcine immune response to generate neutralizing pig immunoglobulins (IgG) that might prevent ASFV infection in vaccinated pig populations, and in doing so, stabilize pork protein food security, relieving the reliance on wild-life protein sources replete with zoonotic potential.