Samples and virus:
African swine fever viruses isolated from diagnostic samples received at ICAR-National Institute of High Security animal diseases, Bhopal during the first outbreaks of ASF were used in this study (Rajukumar et al., 2021). Two ASFV isolates (second passage), from Arunachal Pradesh(IND/AR/SD-61/2020) and Assam(IND/AS/SD-02/2020), were further propagated for one more passage in porcine monocyte culture as described previously by Borca et al., 2020. Briefly, PBMCs of healthy pig were cultured in 10% fetal bovine serum containing RPMI-1640 medium (growth medium). After 48 hours of incubation at 37°C under 5% CO2 concentration, monocytes wereharvestedin Dulbecco’s PBSwith 1mM EDTA after removing unattached cells by thorough washing using PBS. Harvested monocytes were cultured in 24 well culture dishes at the concentration of 2x106 cells per mL in growth medium. The monocytes were infected with supernatants obtained in the second passage at 1/10 dilution.Two wells were maintained as uninfected controls. One hundred µl of freshly prepared 1% swine RBCs in growth medium were added to each well and observed for Haemadsorption for up to 5 days post infection.