Attempts at the Development of a Recombinant African Swine Fever Virus Strain with Abrogated , and Gene Structure using the CRISPR/Cas9 System.

INTRODUCTION

African swine fever (ASF) is a pressing economic problem in a number of Eastern European countries. It has also depleted the Chinese sow population by 50%. Managing the disease relies on culling infected pigs or hunting wild boars as sanitary zone creation. The constraints on the development of an efficient vaccine are mainly the virus' mechanisms of host immune response evasion. The study aimed to adapt a field ASFV strain to established cell lines and to construct recombinant African swine fever virus (ASFV) strain.

MATERIAL AND METHODS

The host immune response modulation genes , , and were deleted using the clustered regularly interspaced short palindromic repeats/caspase 9 (CRISPR/Cas9) mutagenesis system. A representative virus isolate (Pol18/28298/Out111) from Poland was isolated in porcine primary pulmonary alveolar macrophage (PPAM) cells. Adaptation of the virus to a few established cell lines was attempted. The plasmids encoding CRISPR/Cas9 genes along with gRNA complementary to the target sequences were designed, synthesised, and transfected into ASFV-infected PPAM cells.

RESULTS

The reconstituted virus showed similar kinetics of replication in comparison to the parent virus isolate.

CONCLUSION

Taking into account the usefulness of the developed CRISPR/Cas9 system it has been shown that modification of the , , and genes might occur with low frequency, resulting in difficulties in separation of various virus populations.