Raw sewage
Exploring viral diversity in raw sewage
Currently virology is focused on the study of a relatively small number of viral species. Specific viruses are studied either because they are easily propagated in the laboratory or because they are associated with disease. The lack of knowledge of the size and characteristics of the viral universe and the diversity of viral genomes is a roadblock to understanding important issues such as the origin of emerging pathogens and the extent of gene exchange among viruses. Untreated wastewater is an ideal system for assessing viral diversity because virion populations from large numbers of individuals are deposited and because raw sewage itself provides a rich environment for the growth of diverse host species, and thus their viruses. These studies suggest that the viral universe is far more vast and diverse than previously suspected.   Raw sewage was collected and virus particles were purified by milk flocculation.