Association between HHV-6 and MS was proposed after representational difference analysis showed the presence of a DNA fragment homologous to major DNA binding protein gene of HHV-6.[61] Since then, some groups have found increased IgM antibody titers to HHV-6 in MS patients compared to controls, indicating recent infection.[62] Cermelli et al.[63] found the presence of HHV-6 DNA in 57.8% of MS plaques and 15.9% of normal brain samples, a result highly statistically significant (P< 0.0005). This evidence concerns the gene CD40LG and myeloid sarcoma.