A CONSENTED AFRICAN SWINE FEVER VIRUS RIGHT VARIABLE REGION GENE, I1 1L, IS NONESSENTIAL FOR GROWTH IN-VITRO AND VIRULENCE IN DOMESTIC SWINE

The right variable region of the African swine fever virus (ASFV) geno me is known to contain genes with functions involving virus virulence and host range in swine. A novel open reading frame, ORFI11L, which wa s absent in the non-pathogenic, cell culture-adapted European isolate BA71V, was identified in the pathogenic African isolate Malawi Lil-20/ 1,The location of I11L in the right variable region, together with its absence in BA71V, suggested that I11L may have a function in virus vi rulence and/or host range, Here, we show that the I11L gene is highly conserved among pathogenic African, European and Caribbean ASFV field isolates and that it exists either in a short form, encoding a protein of 77-78 amino acids (9.1 kDa) or in a longer form of 93-94 amino aci ds (11.1 kDa), The presence of two predicted membrane-spanning segment s suggests that I11L is an integral membrane protein. RT-PCR analysis demonstrated that I11L mRNA is expressed late in the virus replication cycle, A recombinant I11L gene deletion mutant, Delta I11L, was const ructed from the ASFV isolate Malawi Lil-20/1 to examine gene function, Deletion of I11L did not affect virus replication in swine macrophage cell cultures nor virulence in domestic pigs, indicating that I11L is non-essential for growth in vitro and for virus virulence in domestic swine.