Contrasting Geographic Distribution Profiles of the Herpes Simplex Virus Type 1 BgOL and BgKL Variants in Japan Suggest Dispersion and Replacement

Thelifelong latent infection-reactivation mode of infection of herpes simplex virus type 1 (HSV-1) transmitted by close contact has allowed a diversity of restriction fragment length polymorphism (RFLP) variations to accumulate in human populations. Whether and how the variants of the HSV-1 that is ubiquitous worldwide spread to different human populations is not clear. In our previous study the geographically gradient distribution of the HSV-1 BgKL variant, which is a good marker for the BgKL:SaCFJM:SaGHM:SaD/EL:KpMS variant, suggested that BgKL dispersed geographically. Southern hybridization analyses showed that in BgKL the BglII cleavage site between the BglII K and small “Q/#13” fragments is lost, the SalI cleavage sites between the SalI J and C and between SalI F and J fragments are lost, and the SalI E fragment is abnormally large (SaEL variation). The RFLP and geographic distribution of one more HSV-1 RFLP variant, BgOL, were comparatively analyzed. The BglII cleavage site between the BglII O and Q/#13 fragments is lost in BgOL. BgOL clinical isolates were not associated with any of the SaCFJM, SaEL, SaGHM, or KpMS variations, whereas one-fourth of the non-BgOL:non-BgKL isolates was associated with SaCFJM and SaGHM, indicating that BgKL and BgOL are distant in terms of diversification. BgOL is distributed highly in the northeastern region and the southwestern island of Kyushu but is rare between the two regions in Japan, in a remarkable contrast to BgKL. These are the first epidemiologic data to show contrasting geographic distribution profiles of two HSV-1 variants and suggest the gradual dispersion and replacement of HSV-1 variants.