Modelling population dynamics suggests new way to tackle viral infections

Research lead

Two researchers from the Spanish Centre of Astrobiology (INTA-CSIC) have developed a mathematical model that demonstrates that a mild increase in the mutation rate of some viruses can reduce their infectivity, driving them to extinction.

The model shows how simple evolutionary mechanisms can cause the extinction of populations of fast mutating pathogens, such as certain viruses.

The research suggests that strategies can be devised to fight viral infections by gaining a better understanding of their population dynamics. Instigating a moderate increase in the mutation rate of such viruses could be an alternative to the use of current anti-viral drugs.

The scientists worked with the lymphocytic choriomeningitis virus (LCMV), which infects mice and is sometimes transmitted to humans. This virus does not normally cause serious problems, but occasionally results in death among people with a weak immune system or abortion if infection occurs during pregnancy.

The high mutation rates of these viruses allow them to maintain a reservoir of variants so as to adapt to possible environmental changes and to challenges such as immune system attacks on behalf of the host, or target cell heterogeneity, Susanna Manrubia, one of the researchers said.

The high rate of mutation also produces a high number of unviable mutants. When the scientists added the mutagenic agent fluorouracil, the virus lost its ability to infect cells, though it was still able to replicate. The researchers believe that this occurs because the number of unviable mutants, which can replicate but not infect, act like a cancer destroying the system from the inside.

“The mathematical model formally characterises the extinction of infectivity in these viruses,” said Manrubia. This occurs with small amounts of mutagen and it is a new mechanism for viral extinction that could potentially have clinical uses in the medium term.