Complex sentence: The two identified and related agents of this condition, WEHV1 and WEHV2 respectively, have been observed in lesions of diseased fish although each cell of the infected tissue is host to the specific virus.
Split into simpler sentences: The two identified and related agents of this condition are WEHV1 and WEHV2. Both have been observed in lesions of diseased fish although each cell of the infected tissue is host to the specific virus.