Use of lambda gt11 to identify antigenic components of equine herpesvirus 4

A library of the equine herpesvirus 4 (EHV-4) genome was constructed in the lambda gt11 expression vector. Recombinant bacteriophage expressing EHV-4 antigens as beta-galactosidase fusion proteins were detected with rabbit antiserum raised against EHV-4 virions and convalescent horse serum. EHV-4 DNA sequences contained in the immunopositive recombinants were used as hybridization probes for mapping the genes encoding the antigens on the viral genome. The DNA sequence of the probes was determined. Screening the library with rabbit antiserum led to the identification of 40 recombinants, 26 of which were further characterized. Determination of the DNA sequence of the EHV-4 inserts revealed that 23 of the recombinants encode an identical portion of glycoprotein gB. Two of the recombinants encode a portion of the previously unidentified EHV-4 homologue of the EHV-1 immediate early protein. The EHV-4 insert of the remaining recombinant encodes a portion of the previously unidentified EHV-4 homologue of herpes simplex virus 1 (HSV-1) UL36, a tegument protein. Screening the library with horse serum led to the identification of three recombinants, one of which encodes the same gB sequence as the gB recombinant recognized with the rabbit serum. The other two contain overlapping sequences that encode a portion of EHV-4 gX.