Scientists led by Xin Li of University of Rochester School of Medicine and Dentistry have studied the testes of roosters to learn how our bodies fight viruses.
They examined the role of piRNA – a type of ribonucleic acid (RNA) that’s found most readily in the testes and ovaries – in safeguarding the integrity of the genetic information in germ cells.
It’s known that piRNA shields germ cells by silencing the genetic sequences of viral intruders. Defects or mutations in piRNA lead to infertility in humans and other animals.
Chickens acquire and harbor a wide variety of viruses. When a virus infects a host, like a chicken, it does everything it can to survive. One method of survival is inserting its genetic material into the chicken’s genome. Over generations, the inserted virus accumulates mutations and eventually becomes harmless to the animal, but it’s still a part of the chicken’s genetic material.
Li’s team focused on avian leukosis virus, which commonly infects and can lead to cancer in domestic chickens. Through molecular and genetic analysis, they discovered that chickens turn these old, existing viruses into piRNA-producing machines. When faced with a new avian leucosis virus (there are many different viruses in the family), the old viruses pump out piRNAs that defend the germ cells, ensuring the passage of intact genetic material to the next round of offspring.
“Our study shows how a host can turn a virus into a weapon to fight future viruses,” said Li. “Better understanding piRNA may help us target more viruses, both in chickens and in people.”
More knowledge of how the chickens defend themselves against viral infections could increase the productivity of the poultry industry around the world. Future discoveries in this area can also guide researches benefitting human health as other viruses trapped in the chicken’s genetic code are related to similar viruses in humans.