A recent study investigated whether the sole venomous primate of planet Earth may help us understand why so many people are allergic to cats. The researchers believe cat allergies could be the product of an ancient defense mechanism.
Cat allergies affect an estimated 12.1 percent of people over 6 years of age in the United States. Itchy eyes, a runny nose, coughing, sneezing and wheezing are signs.
Most generally, cats ‘ allergic reaction is a response to a protein called FEL D1. All cats contain FEL D1 and release it from certain glands in our saliva. We spread the protein around their bodies as we lick themselves.
New research by scientists from Australia’s University of Queensland may help explain why this condition is so common in humans. Our dissertation focuses on one of the most uncommon mammals in nature— the slow loris.
The slow loris
“Slow lorises are the only known venom primates, and they have been mostly unstudied,” says one of the scientists, Dr. Bryan Fry, who works at Indonesia’s Cikananga Wildlife Centre.
He continues, “Although a mystery to science, they are often imported from the wild and sold in the pet trade, so our rescue center work was the perfect opportunity to do some good in a bad situation.”
When slow lorises battle each other, they raise their arms and rub the brachial glands that contain venom on their upper arms. In doing so, they blend the venom with saliva and use their incisors to inject this mixture into their opponent, if the opportunity arises.
The venom prevents healing of the bite wound which can lead to death of the tissue, blood poisoning and infections.
It causes an entirely different response in humans, as Dr. Fry explains, “when humans are bitten, the victim will show symptoms as if they are going into allergic shock.” Symptoms include a sensation of burning or tingling, difficulty breathing, pain, and, in the worst cases, near-fatal anaphylactic shock.
Thanks to their mixture of more than 200 aromatic molecules, the slow loris excretions have a distinct odour. Although scientists have identified those chemicals, they know little about the venom’s protein content.
Unraveling the protein
The researchers decided to investigate slow loris venom in more depth, taking advantage of their unique exposure to these rare primates, and they studied the protein DNA sequence in it. Their results were published in the journal Toxins.
Ironically, as Dr. Bryan describes, they find that it is “virtually identical with the allergenic protein on cats.”
The authors assume that this near resemblance could not have happened by accident. Assuming that this chemical is used as a protection by the slow loris, they wonder if FEL D1 might have evolved to help defend cats from predators.
The authors note that the similarities between slow loris venom and FEL D1 are “reflective not only of shared molecular evolutionary history, but also indicative of similar functionality.”
“This capacity to cause allergy as a tool may not have been limited to slow lorises, but at the same time may have evolved separately in cats. This is a fascinating hypothesis that we are looking to test in future research.”
– Dr. Bryan Fry
Because human cat allergies are so common, Dr. Fry suggests it would be “a remarkable coincidence if this wasn’t an evolved defensive weapon, like the same protein used by slow lorises.”
Only a small number of mammals, including the platypus and vampire bat, are venous. Scientists know very little about its origin, because nature has not equipped other animals with this type of weaponry. This work adds a new piece of information to the otherwise small portion of study that is devoted to venom evolution in mammals.
