Identification of genes encoding late expression factors located between 56.0 and 65.4 map units of the Autographa californica nuclear polyhedrosis virus genome.

Using a previously developed method that allows the identification of Autographa californica nuclear polyhedrosis virus (AcMNPV) genes which stimulate transient expression from a late and a very late viral promoter [Passarelli and Miller, J. Virol., 67, 2149-2158 (1993)], we have identified three genes between 56.0 and 65.4 map units of the AcMNPV genome involved in expression from a late and a very late promoter but not from an early viral promoter. One gene, p143, was previously shown to be essential for viral DNA replication and shares sequence motifs with DNA helicases [Lu and Carstens, Virology, 181, 336-347 (1991)]. The second gene, previously sequenced and originally referred to as open reading frame 6 (herein renamed late expression factor-5 [lef-5]), was located just downstream of the 6.9 kilodalton core protein gene, p6.9. The third gene, late expression factor-4 (lef-4), was defined and sequenced. The lef-4 gene was located immediately upstream of, and in opposite orientation to, the major capsid protein gene, vp39. The position and direction of lef-4 appeared to be conserved in the Orgyia pseudotsugata and Lymantria dispar nuclear polyhedrosis viruses. The gene product of lef-4, LEF-4, is predicted to be an acidic polypeptide (pl 4.91) of 464 amino acids in length with a molecular mass of 53,913 daltons.