The body clock may play a key role in determining susceptibility to viral infection, researchers reported last night.
The findings may explain why shift workers can be vulnerable to viruses – and why they should get the flu vaccine, according to researchers to Cambridge University, UK.
The study on nocturnal mice suggests that vulnerability to infection is greatest when the body is expecting to rest.
In the mice this was at sunrise, when they start their resting phase. When they woke and became active, they were least vulnerable to infection.
The difference in viral replication rates between the two periods was ten times, the researchers found.
Further research involved mice genetically altered not to have a body-clock gene, Bmal1. These were especially vulnerable to infection – suggesting the body clock plays a key role in resistance.
The researchers have reported their findings in the Proceedings of the National Academy of Sciences.
Researcher Professor Akhilesh Reddy said: “The time of day of infection can have a major influence on how susceptible we are to the disease, or at least on the viral replication, meaning that infection at the wrong time of day could cause a much more severe acute infection.
“This is consistent with recent studies which have shown that the time of day that the influenza vaccine is administered can influence how effectively it works.”
He added: “Given that our body clocks appear to play a role in defending us from invading pathogens, their molecular machinery may offer a new, universal drug target to help fight infection.”
Edgar, RS et al. Cell autonomous regulation of herpes and influenza virus infection by the circadian clock. PNAS 15 Aug 2016; doi: 10.1073/pnas.1601895113
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