This study investigated the chemical structure of African swine fever virus (ASFV) using electron microscopy and enzymatic digestion. Two virus isolates (LISBON-57 and HINDE) were grown in pig kidney tissue culture cells, embedded in glycol methacrylate, and treated with specific enzymes: RNase, trypsin, pepsin, and DNase. The results revealed distinct structural compartments of the virus. Treatment with pepsin removed the outer hexagonal membrane, exposing a densely staining central core. DNase digestion removed this inner core, indicating DNA presence. Conversely, RNase and trypsin had no effect on viral structure. The findings confirmed that ASFV contains infectious DNA and lacks RNA. The virus has a distinctive morphology consisting of a protein-containing outer hexagonal membrane with DNA localized exclusively in the central core. These observations paralleled earlier findings in leopard frog renal tumors, suggesting similar structural organization across different virus systems.

Key findings

• African swine fever virus contains DNA as its genetic material and lacks RNA
• The virus has a distinctive two-component structure: a protein-containing outer hexagonal membrane and a DNA-containing central core
• Pepsin digestion selectively removes the outer hexagonal membrane while DNase digestion removes the inner DNA-containing core
• RNase and trypsin treatment had no effect on viral structure, confirming absence of RNA and that the outer membrane is protein but not susceptible to trypsin