Since HHV-6, like HCMV, is a beta-herpesvirus, anti-HCMV drugs such as (val)
ganciclovir,
foscarnet and
cidofovir may, by extrapolation, be advocated for the treatment of HHV-6
infections. At present, no prime candidate for the treatment of HHV-6
infections has been identified or even proposed, which means that the search for
antiviral drugs effective against HHV-6-associated diseases should be encouraged. In essence, this search is going into two directions:
nucleoside and non-
nucleoside analogues. To the first category belong
S2242, an N7-substituted
purine acyclic derivative;
A-5021, a cyclopropyl
nucleoside analogue;
cyclopropavir, a methylene
cyclopropane analogue; lipophilic
ester prodrugs of the acyclic
nucleoside phosphonate cidofovir; and various other "old" and "new" acyclic
nucleoside phosphonate analogues including those derived from the 2, 4-diaminopyrimidine (DAPy) skeleton. To the non-
nucleoside category belong a number of
quinoline-3-carboxamide, aryl
sulfone,
benzimidazole riboside and phenylenediamine
sulfonamide derivatives which could be further optimized from a structure-activity relationship (SAR) viewpoint so as to specifically target HHV-6 replication. Also, specific
protein kinase inhibitors may be pursued as anti-HHV-6 agents, a representative example being the compound CMV423 which, being inhibitory to (cellular)
protein tyrosine kinases, exhibits potent and selective activity against HHV-6.