In folklore, the jackalope—a mythical rabbit with the antlers of a deer—has long been a whimsical symbol of the American West. Tales of this elusive creature have been passed down for generations, blurring the line between fact and fiction. But what if the legend of the “horned rabbit” was inspired by a very real, albeit startling, biological phenomenon? The truth is, a specific virus can cause rabbits to develop bizarre, horn-like growths, and the story of its discovery is a fascinating chapter in both wildlife biology and human medicine. This is the tale of the Shope papillomavirus, a remarkable virus that not only gave rise to a popular myth but also paved the way for a major medical breakthrough.
The Scientific Discovery That Validated a Myth
For centuries, stories of horned rabbits appeared in folklore and even early scientific treatises. However, it wasn’t until the 1930s that science began to catch up with the legend. Richard E. Shope, a pioneering cancer researcher, was working in Princeton, New Jersey, when he heard reports from hunters in Iowa about rabbits with strange horn-like protrusions. Intrigued, Shope obtained some of the afflicted rabbits, and his investigation led to a groundbreaking discovery.
In 1933, Shope successfully isolated a virus from the growths, proving that a microorganism was the cause of the tumors. He named the virus the Shope papillomavirus (SPV), and his work provided the first-ever mammalian model for a virus-induced cancer. Shope’s discovery gave the myth of the jackalope a tangible, biological origin, suggesting that hunters and early naturalists had likely been observing animals suffering from this viral infection all along.
The Biology of the “Horned” Rabbit
The Shope papillomavirus is a species-specific virus that primarily infects wild cottontail rabbits. It is a type of DNA virus belonging to the papillomavirus family, which is also responsible for warts in humans. The virus is often transmitted through biting insects like mosquitoes and ticks, or through direct contact between rabbits. Once a rabbit is infected, the virus causes the proliferation of epithelial cells, leading to the formation of tumors.
These growths, which can appear anywhere on the rabbit’s body but are most common on the face and head, are essentially large keratinous carcinomas—hard, wart-like masses made of keratin, the same protein found in hair, skin, and fingernails. While the sight of these “horned” rabbits can be alarming, it’s important to remember that the virus is not transmissible to humans or other common pets.
The Impact on the Rabbit’s Survival
While the tumors caused by SPV are often benign, their location and size can have serious consequences for the infected rabbit. Growths around the eyes can obstruct vision, making it difficult for the rabbit to forage for food and water or to spot predators. Tumors near the mouth can physically block the animal’s ability to eat and drink, leading to malnutrition and ultimately, starvation.
In some cases, the virus can be fought off by the rabbit’s immune system, causing the tumors to regress and fall off. Rabbits that survive the infection often develop immunity to future re-infection. However, in other cases, especially in domestic rabbits, the tumors can become cancerous and spread, leading to a much more severe and often fatal outcome. The outcome of the infection depends heavily on the rabbit’s overall health and the location and size of the growths.
A Legacy That Led to the HPV Vaccine
Perhaps the most astonishing part of the Shope papillomavirus story is its lasting impact on human medicine. For decades after its discovery, the virus served as a crucial model for studying how viruses can cause cancer. Researchers used the “horned rabbit” model to understand fundamental mechanisms of viral oncology, laying the groundwork for future discoveries.
This foundational research on SPV directly contributed to the development of our understanding of Human Papillomavirus (HPV), which is the primary cause of cervical cancer and other cancers in humans. The successful development of the HPV vaccine, a landmark achievement in modern medicine, was built on the knowledge gained from studying this virus in rabbits. In this way, the seemingly bizarre affliction of a wild rabbit became a key to saving human lives.
What to Do If You See a “Horned Rabbit”
If you encounter a wild rabbit with growths that resemble horns, the best course of action is to observe from a distance. Do not attempt to catch or handle the animal, as you could cause it unnecessary stress or injury. While the virus is not a threat to humans, all wild animals can carry other diseases, and it’s always safest to maintain a respectful distance.
If the rabbit appears to be in severe distress, contact a local wildlife rehabilitation center or animal control. They have the expertise and resources to assess the situation and provide professional care if necessary. For domestic rabbits, the virus is much less common but can occur. If you notice any unusual growths on your pet rabbit, a visit to a veterinarian is essential for a proper diagnosis and treatment plan.
Table of Contents
How the First IBM PC Changed Computing Forever – trendsfocus