ASFV vaccine candidate produced in a continuous cell line

The U.S. Department of Agriculture’s Agricultural Research Service (ARS) has announced that an African swine fever virus (ASFV) vaccine candidate has been adapted to grow in a cell line, which means that those involved in vaccine production will no longer have to rely on live pigs and their fresh cells for vaccine production.

“This opens the door for large-scale vaccine production, which is a valuable tool for the possible eradication of the virus,” said senior ARS scientist Dr. Manuel Borca.

No commercial ASFV vaccines are currently available.

The ARS researchers recently developed a vaccine candidate, ASFV-G-ΔI177L, by deleting the I177L gene from the genome of the highly virulent pandemic ASFV strain Georgia (ASFV-G).

Their latest discovery, highlighted in the Journal of Virology, overcomes one of the major challenges for manufacturing of an ASFV vaccine. The researchers developed an ASFV-G-ΔI177L derivative strain, ASFV-G-ΔI177L/ΔLVR, that efficiently replicates in a continuous cell line. The newly developed vaccine has the same characteristics as the original vaccine produced with fresh pig cells.

“Traditionally we used freshly isolated swine cells to produce vaccine candidates and this constitutes a significant limitation for large-scale production” said senior ARS scientist Dr. Douglas Gladue. “But now we can retain the vaccine characteristics while simultaneously replicating the vaccine in lab-grown cell cultures. We no longer have to rely on gathering fresh cells from live swine.”

The continuous cell line vaccine candidate was tested in a commercial breed of pigs and determined to be safe, protecting pigs against the virus. No negative effects were observed.

Article: Borca, M. V., Rai, A., Ramirez-Medina, E., Silva, E., Velazquez-Salinas, L., Vuono, E., Pruitt, S., Espinoza, N., Gladue, D. P. (2021). A cell culture-adapted vaccine virus against the current pandemic African swine fever virus strain. Journal of Virology, advance online publication, doi: 10.1128/JVI.00123-21