Scientists are working hard to make pet-related sneezes and sniffles a distant memory, and there's promising news from researchers analyzing the potential for a vaccine against dog allergies. In what's being described as a first step in developing such a vaccine, a team in Japan has identified certain parts of molecules that may be responsible for causing an allergic reaction in people whenever a dog is around. Once these molecular sections have been spotted and isolated, they can potentially be targeted by a vaccine that lessens the immune response they trigger. These sections are technically known as epitopes – strings of amino acids that compose part of the protein that our bodies perceive as a threat. "We want to be able to present small doses of these epitopes to the immune system to train it to deal with them, similar to the principle behind any vaccine," says molecular biologist Takashi Inui from Osaka Prefecture University in Japan. Here the researchers focussed on a particular dog allergen called Can f 1, one of seven such allergens that have previously been identified, and thought to be responsible for 50-75 percent of reactions in people who are allergic to dogs. Using a technique called X-ray crystallography (where X-ray diffraction reveals the crystal structure of a material), the team was able to determine the structure of the Can f 1 protein in its entirety, something that hasn't been done before. Key differences between Can f 1 and other similar allergens were identified, pointing towards what researchers think are strong candidates for epitopes. Further experimental work should be able to narrow down these candidates even further. "The structure of Can f 1 is similar to that of other dog lipocalin [a family of proteins] allergens," write the researchers in their published paper. "However, the distribution of surface charge on these proteins varies greatly." For someone with a dog allergy, the epitopes the scientists are looking for can be thought of as being like puzzle pieces that fit with matching pieces constructed by our on immune system – antibodies carried by B cells, or T Cells – for easy identification. It's essentially hunting down the cause of the allergic reaction. This epitope-led way of developing a vaccine is by no means a common one, and if scientists are able to make it happen with regards to dog allergies, it's hoped that the same process might be used to develop other types of vaccines in the future. We're still at the very early stages with this, so dog allergy sufferers may have to carry on avoiding close contact with pooches for a while yet – but we could one day look back on this as the first important step towards a working vaccine. "These allergens can cause severe allergic reactions, such as asthma, allergic rhinitis, and allergic conjunctivitis in 5-10 percent of the population," write the researchers. "As contact between dogs and humans becomes more frequent and intimate, dog allergies have become increasingly prominent worldwide, particularly in advanced nations. Source
