Or, more aptly, in the gut viriome? Although we often associate viruses with deadly disease and cancers, they may also be necessary for a healthy, well balanced gut.
For the first time, a study has shown that a virus can confer similar functional benefits as bacteria. Germ-free mice are prone to have poor immune function and very thin villi, which reduces the ability of the mice to absorb nutrients. It has previously been shown that giving germ-free mice certain bacteria can rebalance the immune system and improve their villi.
In their 2014 study, Kernbauer, Ding and Cadwell showed that giving these mice a norovirus had the same effect. To support their observations, they also gave normal mice antibiotics for two weeks, observed their decline in health, and gave them the norovirus, which helped the mice recover -- even better than replacement of bacteria. Similarly, when they infected antibiotic-treated mice with a pathogen, the addition of norovirus also helped their recovery.
The mechanisms of these observations have yet to be understood or replicated in humans. However, it is heartening to think that perhaps the infamous "cruise ship" virus may do more than make us spew out our guts.