Since AMGs originate in hosts, distinguishing host and viral genes is critical for their study. This is not easily achieved as cultivation of viral-host systems in a laboratory setting proves challenging if even possible. Additionally, filtering out cellular sequences before entry in bioinformatic pipelines is not possible with cellular gene transfer agents and membrane vesicles are unable to distinguish from viruses due to their many shared properties at this step of analysis. The extent to which they have contaminated existing viral databases is unknown. Some genes have distinctions between host and viral versions such as cyanophage photosynthesis easing the task of computational distinction. The most definitive way developed to determine gene origin has been identification of taxonomically informative genes colocalized on assembled contigs. ViromeQC can display contamination for the dataset overall and DRAM-v assigns a confidence score for the AMG being on a viral MAG. Viral identification is most popularly performed by VIBRANT, VirSorter2, DeepVirFinder, and CheckV.