PRV Genome and Gene Organization

The complete annotated PRV genome sequence can be accessed from Genbank.

The PRV genome in the virion consists of a double-stranded DNA 143,700 bp in length with a G+C content averaging 74%. The genome is in a linear form in the virion but circularizes in the cell prior to replication.

The genome contains unique long (UL) region of 101.1 kb and a unique short (US) region of 8.7 kb. The US region is bracketed by the IRS and TRS, two large inverted repeats 16.8 kb in length. Three origins of replication are known, one in the UL and one in the IRS and TRS.

The figure below depicts the arrangement of the 73 genes (72 open-reading frames and the large latency transcript [LLT]) and their predicted transcripts in the PRV genome.

Genome MapTN

Genome Map (PDF)

The gene content and arrangement in the PRV genome are similar to those of HSV-1 and the other alphaherpesviruses. Indeed, the PRV genome is colinear with these viruses except for an internal inversion of 39 kb extending from UL27 (gB) to UL44 (gC).

Only a few genes have been found to be spliced in alphaherpesviruses, usually immediate-early (US1) or latency genes (LLT), as splicing is generally inhibited in productive infections. Co-terminal transcripts (mRNAs sharing the same 3' end) are frequent (48 of 73 genes in PRV). Seven of the 11 PRV repeat DNA regions separate convergent transcripts. Divergent transcripts in close proximity to each other raise the possibility of sharing regulatory sequence elements. Indeed, there are six cases of genes predicted to share the same TATA box (bidirectional TATA) and six cases of sequences predicted to function both as a TATA box and a polyA site (bifunctional TATA-polyA). More details on the genome and gene organization in [1].

View detailed information on the functions of virally-encoded PRV proteins at the  Laboratory for Molecular Biology of Herpesviruses in the Institute of Molecular Biology at the Friedrich-Loeffler-Institut.

[1]Klupp BG, Hengartner CJ, Mettenleiter TC, Enquist LW.  Complete, annotated sequence of the pseudorabies virus genome. J. Virol., 78(1):424-440.

Pseudorabies Virus (PRV)