A common topical antibiotic applied to mice before or shortly after infection with herpes and other viruses triggered an antiviral resistance in the animals, researchers found. A Yale-led research team made this startling discovery while investigating the effect of bacteria on viral infections. The study was published in Nature Microbiology.

The research team, led by immunobiologist Akiko Iwasaki, who is also an investigator of the Howard Hughes Medical Institute, focused on one antibiotic, neomycin, which decreased the herpes virus and symptoms in infected mice. They studied gene expression in the treated mice and observed greater expression of genes that are stimulated by interferons -- proteins that block viral replication. Through further investigation, they determined that neomycin triggered a receptor in the mouse immune cells that responded to the antibiotic as if it was a viral infection.

The research team also confirmed neomycin's antiviral effect in mice infected with the flu and Zika viruses, said Smita Gopinath, the primary author of the study.