Paternal COVID infection may have effects that go far beyond the person who caught the virus. Most of us accept that COVID-19 transformed the planet, yet researchers now report that the pathogen could leave an even more intimate mark: in the sons and daughters of those it once infected. A new study from researchers in Australia reveals that male mice infected with SARS-CoV-2, passed on changes to their offspring, making them more anxious. The fathers had long since recovered fully before reproduction, yet the behavioral shift still persisted.
The study behind the discovery
To test the idea, researchers deliberately exposed healthy adult male mice with a version of the COVID virus. After recovery, and once they were no longer contagious, the treated males joined healthy untouched females for mating. Two short weeks slid by. The pups (known as the F1 generation) arrived. These youngsters had never met the pathogen, yet as they grew up something unusual emerged. Investigators watched their behavior with care. Progeny of the previously infected sires displayed greater anxiety. They lingered less in bright or open arenas, an established marker of mouse fear. Interestingly, the effect appeared stronger in male adults than in their female siblings.
COVID alters sperm RNA
The scientists discovered that the fathers’ sperm carried altered arrays of tiny molecules called small noncoding RNAs. These molecules do not build proteins as ordinary genes do, yet they act like minute “switches” that help decide when genes switch on or off. When the researchers injected these modified sperm RNAs into healthy fertilized eggs, the ensuing offspring developed matching anxiety traits even though no virus was ever present. That shows the alterations in the sperm’s RNA were sufficient to pass the effect along.
A message written in molecules
It’s as though the infection scribbled a subtle “memory” inside the sperm, not by changing the DNA letters themselves, rather by adjusting the way those letters get read. This form of inheritance is called epigenetic inheritance, where experiences, such as stress, diet, or infection, can sculpt how later generations meet life.The scientists further discovered that within the offspring’s brains certain genes in the hippocampus, a region that guides emotion and memory, were dialed either up or down in striking patterns. Many of those genes carry ties to stress and to anxiety.
Does it last beyond one generation?
The team looked further at the grandchildren (F2 generation) of the infected fathers. The grandpups showed modest shifts in early growth and litter size, but their adult behavior, for the most part, normal. That suggests the strongest effects appear in the first generation, fading after that.
What this means for human health
This study poses a vital question: Can infections in parents alter the future mental health of their children?
If the answer is yes, knowing why could guide doctors and scientists to new ways to shield future generations, perhaps by finding the safest time for conception after recovery, or by creating treatments that undo molecular shifts.