human betaherpesvirus 6a human betaherpesvirus 6a human betaherpesvirus 6a (hhv-6a) is a species of virus in the genus roseolovirus, subfamily betaherpesvirinae, family herpesviridae, and order herpesvirales. human betaherpesvirus 6a virus classification (unranked): virus realm: duplodnaviria kingdom: heunggongvirae phylum: peploviricota class: herviviricetes order: herpesvirales family: herpesviridae genus: roseolovirus species: human betaherpesvirus 6a synonyms human herpesvirus 6 taxonomy in 1992 the two variants were recognised within human herpesvirus 6 on the basis of differing restriction endonuclease cleavages, monoclonal antibody reactions, and growth patterns. in 2012 these two variants were officially recognised as distinct species by the international committee on taxonomy of viruses and named human betaherpesvirus 6a and human betaherpesvirus 6b. despite now being recognised as paraphyletic, the name human herpesvirus 6 still sees usage in clinical contexts. pathology