The human virome in health and disease

Viruses can influence human health in various ways. Some viruses directly cause pathogenic infections, while others can trigger a protective immune response that may prevent infection by other pathogens. Viruses can activate immune responses through TLR signaling and other molecules, which can be either beneficial in preventing infection or detrimental if the immune response is ineffective and leads to infection by another pathogen.

In addition, viruses can modulate bacterial abundance as predators and transfer DNA into bacteria, influencing their fitness and virulence. For example, cholera toxin is carried on a phage, so the severity of cholera infection depends on the presence of this phage. Overall, we are just beginning to understand the many ways in which viruses can impact human health.