LAT and disease arising from reactivation of latent virus: Since this 2.8 kb LAT region in the context of the chimeric viruses did influence differential latent infection, we hypothesized that a trans-acting factor expressed by the LAT transgene in the mice should be able to direct differential latent infection if the mice were infected with the heterologous virus serotype (i.e. HSV-1 LAT-expressing mice infected with HSV-2).