Subfamily: Alphaherpesvirinae

Genus: Simplexvirus

Distinguishing features

The predicted amino acid sequences of members form a distinct lineage within the subfamily (Figure 1. Alphaherpesvirinae). 

Virion

See discussion under family description. 

Genome organization and replication

Members have a class 4 genome architecture (Figure 2.Orthoherpesviridae and Figure 3. Orthoherpesviridae). Among the human viruses in this genus, herpes simplex virus type 1 (HSV1 in the species Simplexvirus humanalpha1) displays greater intraspecies diversity than herpes simplex virus type 2 (HSV2 in the species Simplexvirus humanalpha2) (Szpara et al., 2014, Pfaff et al., 2016, Johnston et al., 2017, Akhtar et al., 2019).  Interspecies recombinants between HSV1 and HSV2 have been detected in clinical specimens (Burrel et al., 2017, Koelle et al., 2017). 

Biology

Members have mammals, mostly primates, as hosts. The most common symptoms of HSV1 and HSV2 infection are watery blisters in the skin or mucous membranes of the mouth (cold sores) or genitals (genital herpes), respectively. Latent infection is established in neurons, and reactivation of latent virus may occur to produce recurrent symptoms. Antigenicity Members may cross-react serologically. 

Species demarcation criteria

See discussion under family description.