Submitted to: International Congress On Apoptosis
Publication Type: Proceedings
Publication Acceptance Date: February 1, 2003
Publication Date: February 1, 2003
Citation: Zsak, L., Sur, J.H., Burrage, T.G., Neilan, J.G., Rock, D.L. 2003. African swine fever virus (asfv) multigene family (mgf) 360 and mgf 530 genes affect virulence, pathogenesis and immuno response in swine [abstract]. International Congress On Apoptosis. p. 618.
Recently, we reported that ASFV MGF360 and MGF530 genes are significant macrophage host range determinants and they function by promoting infected cell survival. To examine gene function(s) gene deletion mutant, Md35, and its revertant, Md35-R, were constructed from pathogenic ASFV isolate, Malawi Lil-20/1 (MAL). Deletion of six MGF360 and two MGF530 genes from MAL markedly reduced viral growth in swine macrophage cell cultures by 100-fold. Cell viability and TUNEL assays revealed accelerated and increased apoptotic cell death in macrophage cell cultures infected with Md35. In addition, Md35 was considerably attenuated in swine. Immunohistochemistry revealed a markedly reduced number of Md35-infected cells in lymphoid tissues, however, a significantly increased rate of apoptotic cell death was observed in Md35-infected tissues when compared to Md35-R. These data indicate that reduced viral growth in macrophages together with increased early apoptotic death of virus-infected cells likely account for the attenuation of Md35 in swine. To study protective immune response following infection with Md35, surviving animals were challenged with pathogenic MAL virus at 42 days post infection (dpi). Significantly, all Md35-infected pigs were protected from the acute form of ASF, however, animals developed chronic ASF symptoms between 21 and 52 dpi. Thus, MGF360 and MGF530 genes may function as important determinants in protective immune response for ASF.