Viruses interact with other species of viruses but the ways in which they do this are little understood. Applying our understanding of animal behavior to these protein-coated tiny pieces of genetic material, Dr Samuel Diaz-Muñoz of the University of California Davis, argues, can open up new ways to think about, and fight, agents of infectious disease.
The mixing of genetic material that goes on when strains of a virus such as influenza co-infect the same host is one of the reasons vaccines struggle to keep up with rapid changes in certain species. When co-infecting viruses are of different species, competition ensues as to which will get to control the host’s cells to allow it to replicate. An ecosystem forms, which Diaz-Muñoz argues in Cell Host & Microbe resembles the way animals compete and cooperate on a coral reef or in a rainforest.
“We’ve seen more and more how things we didn’t think were social are social and there are a lot of fundamental biological processes that are social,” Diaz-Muñoz said in a statement. “I’m interested in how interactions between individuals affect reproduction. And reproduction, of course, is key for evolution.”
The idea of social interaction between viruses has not caught on, Diaz-Muñoz argued, because they clearly lack cognitive capacity. However, evolution can produce something that closely replicates social behavior without requiring any brains at all.
Only a bad parasite kills its host – killing the goose that lays the golden eggs – but viruses lack the intelligence to understand this. Nevertheless, natural selection has promoted infectious agents with the capacity to slow down reproduction in order to keep hosts alive long enough to transmit to others, resembling cooperative behavior in more advanced life forms.
Wherever there is cooperation there are those who cheat, coasting on the benefits provided by others without assisting the common good themselves. Certain viruses, for example, are known to use the replication of others to enable their own reproduction. Pushback against cheaters can occur even in organisms with no capacity to understand they have been cheated.
Diaz-Muñoz originally worked in the study of social behavior of tamarin monkeys, but as he heard about the interactions between viruses he decided the skills he had learned might be transferable.
“Even though we’re using words like ‘conflict’ and ‘cooperation’ that colloquially mean certain things, these are actually based on mathematical theory and do not require complex cognitive processes,” Diaz-Muñoz explained. “You don’t need complex cognition to have social evolution.”
Only by understanding the way viruses treat each other, Diaz-Muñoz believes, can we learn the weaknesses that give us the best chance to control them.