A whale of a mystery
Of the 60 mammals whose genomes were compared recently by School of Medicine researchers, only toothed whales, like dolphins and orcas, lack functional Mx genes — the source of key antiviral proteins that fight viruses such as HIV, measles and flu.
“Given how important the Mx genes seem to be in fighting off disease in humans and other mammals, it’s striking to see a species lose them both and go about its business for millions of years,” says Gill Bejerano, PhD, associate professor of developmental biology, of computer science and of pediatrics. He hypothesizes that the common ancestor of these mammals was subjected to a virus that exploited the Mx genes, and “their option was to lose both genes or die.”
Bejerano is the senior author of the study, published in June 2015 in the Proceedings of the National Academy of Sciences. The researchers hope others will investigate whether toothed whales’ immune systems are compromised — a possible explanation for recent die-offs — or whether they’ve developed compensatory mutations. Ultimately, this could lead to new treatments for human autoimmune disorders.
“We’re putting the genomic discovery out there, and we hope immunologists will follow up on it,” says Bejerano. “This is an amazing time to be a thoughtful genomicist. And hopefully, we’ve helped make it a slightly better time to be a toothed whale.”