Evolution of herpes simplex virus type 1 under herpesviral evolutionary processes.

Herpesviruses, the genomes of which are double-stranded DNA of 120 kilobase pairs or more, infect a wide range of vertebrates from mammals to fish. Herpes simplex virus type 1 (HSV-1), a representative of family Herpesviridae, is a ubiquitous human pathogen. HSV-1 relates to common mucocutaneous diseases, while HSV-1 infection can mean a serious outcome, e.g. blindness and insult to the central nervous system. Evolution of herpesviruses includes DNA rearrangements, often generating tandemly or invertedly repeated sequences. Studies of HSV-1 DNA dynamics substantiated these processes of DNA recombination involved in the evolution of herpesvirus. Herpesviruses seem to have diversified from a common ancestor, in a manner mediating co-speciation of herpesviruses with host species through species-specific latent infections. Thus, the notion of host-linked evolution of herpesviruses is given support. Relationships between HSV-1 genotypes and human ethnic groups can be traced by analyses of DNA polymorphisms of HSV-1 strains present in populations of various countries. A close association of an HSV-1 genotype with a particular historical human population seems probable. Such being the case, the host-linked mode is likely to be linked to diversification of HSV-1 in human populations.