An African swine fever virus ORF with similarity to C-type lectins is non-essential for growth in swine macrophages in vitro and for virus virulence in domestic swine

An African swine fever virus (ASFV) ORF, 8CR, with similarity to the C-type lectin family of adhesion proteins has been described in the pathogenic is olate Malawi Lil-20/1. The similarity of 8CR to cellular and poxvirus genes associated with cell adhesion, cell recognition and virus infectivity sugg ested that 8CR may be of significance to ASFV-host cell interactions, Seque nce analysis of the 8CR ORF from additional pathogenic ASFV isolates demons trated conservation among isolates from both pig and tick sources. Northern blot analysis demonstrated 8CR mRNA transcription late in the virus replic ation cycle. A Malawi Lil-20/1 8CR deletion mutant (Delta 8CR) was construc ted to analyse 8CR function further. The growth characteristics in vitro of Delta 8CR in porcine macrophage cell cultures were identical to those obse rved for parental virus. In domestic swine, Delta 8CR exhibited an unaltere d parental Malawi Lil-20/1 disease and virulence phenotype. Thus, although well conserved among pathogenic ASFV field isolates, 8CR is non-essential f or growth in porcine macrophages in vitro and for virus virulence in domest ic swine.