Complex sentence: Although both virus types have been observed in lesions of diseased fish, each cell of the infected tissue is host to a specific virus and transmission studies have shown that WEHV-2 has been the more proliferative agent of the condition as compared to WEHV-1.
Split into simpler sentences: Although both virus types have been observed in lesions of diseased fish, each cell of the infected tissue is host to a specific virus. Transmission studies have also shown that WEHV-2 has been the more proliferative agent of the condition as compared to WEHV-1.