Getting a Dog to Make Its Own Anti-Itch Antibodies A Virus Shaped Vaccine for Canine Atopic Dermatitis

Canine atopic dermatitis is a lifelong itch. The current treatments work, and they mostly work by suppressing something, daily, forever. This application takes a different route: display the dog’s own itch signalling protein on the surface of a plant virus shell, inject it, and let the dog’s immune system produce antibodies that neutralise the protein. The applicant is Saiba Animal Health AG, a Swiss veterinary biotech spun out of the University of Zurich.

The Problem

Canine atopic dermatitis affects up to 10 per cent of all dogs, which makes it the second most common allergic skin condition in the species after flea allergy. It is an inflammatory, intensely pruritic disease arising from an interaction of genetic and environmental factors. Signs typically appear young, with peak onset between six months and three years, and show up on the face, ears, paws, extremities, underside and flex zones as reddened, eczematous skin. Dogs scratch, lick their paws, lose hair, break the skin from deep scratching, and pick up secondary infections in the damage they have done to themselves. It is chronic and relapsing, and the veterinary literature is clear that most affected dogs need ongoing, usually lifelong, therapy.

The available drugs all have the same shape of limitation. Antihistamines such as fexofenadine, immunosuppressants such as ciclosporin, and more recently the Janus kinase inhibitor approved for the condition are all effective to varying degrees. All of them carry side effects that constrain long-term use, principally immune suppression and the infections that follow it. Corticosteroids add osteoporosis, endocrine disturbance and cataracts to the list, along with the increased eating, drinking and urination that owners find hard to live with.

There is a practical problem layered on the pharmacological one. Most of these treatments are given orally and daily. For a condition that persists for the animal’s life and depends on an owner’s consistency, daily dosing is a compliance problem as much as a medical one. The alternative currently on the market, an injected monoclonal antibody against interleukin-31, works well but has to be re-administered every few weeks and, like all monoclonals, is expensive to manufacture.

What This Invention Does

The target is interleukin-31, a cytokine that sits close to the centre of the itch pathway. The specification’s account is that in canine atopic dermatitis, immune cells, keratinocytes and direct neuronal stimulation together drive inflammation and pruritus, and that canine IL-31 is the signal that translates that activity into itching. Reduce circulating cIL-31 and you reduce scratching, and by reducing scratching you cut off the downstream cascade of skin damage, inflammation and infection.

The claimed composition has two components held together in a specific way. The first is a core particle carrying at least one attachment site, preferably a recombinant virus-like particle. The second is a canine IL-31 antigen carrying at least one attachment site of its own, defined in the claims by reference to a specific sequence or a variant with at least 90 per cent identity to it. The two are joined through those attachment sites by a non-peptide covalent bond, typically through an introduced cysteine and a hetero-bifunctional cross-linker, rather than by expressing the two as a single fusion protein.

The preferred core particle is a modified virus-like particle of cucumber mosaic virus, a plant virus that infects no vertebrate. The modification is the interesting part: the viral coat protein is engineered to carry a T helper cell epitope derived from tetanus toxin. That borrowed epitope recruits help from T cells the dog already has, from prior vaccination, which strengthens the antibody response to whatever is displayed on the particle’s surface.

That surface display is the mechanism the whole design turns on. IL-31 is a self protein, and the immune system is built not to attack self proteins. Presenting it in a dense, highly repetitive, para-crystalline array on the outside of something that looks unmistakably like a virus is what breaks that tolerance. The particle triggers the response a viral attack would trigger; the antigen bolted to its surface is what the resulting antibodies bind. The specification reports that vaccinated dogs produced cIL-31 specific antibodies and that scratching was strongly reduced, with the reduction correlating with antibody induction, scored against a pruritus visual analog scale running from zero to ten.

Key Features

• Self antigen displayed on a viral shell. Canine IL-31 is presented in a repetitive ordered array on the particle surface, which is what allows the immune system to respond to a protein it would normally ignore.
• Cucumber mosaic virus derived core. The virus-like particle comes from a plant virus with no vertebrate host, produced recombinantly rather than isolated from infected material.
• Borrowed tetanus T helper epitope. The coat protein is modified to carry a T helper cell epitope derived from tetanus toxin, recruiting pre-existing T cell help to boost the antibody response.
• Chemical rather than genetic linkage. Antigen and particle are joined by a non-peptide covalent bond through defined attachment sites, commonly an added cysteine and a hetero-bifunctional cross-linker, rather than as a fusion protein.
• Sequence defined antigen. The claims specify the canine IL-31 antigen by sequence, with a tolerance band down to 90 per cent identity for variants.
• Active rather than passive immunity. The dog produces its own neutralising antibodies, which is a structurally different proposition from repeat injections of a manufactured monoclonal antibody.

Who Is Behind It

Saiba Animal Health AG was founded in 2013 as a spin-off from the University of Zurich and built a pipeline of therapeutic vaccines for chronic conditions in companion animals, all on the same cucumber mosaic virus particle platform. Its programs include vaccines aimed at allergy in cats and dogs and at inflammatory pain in dogs, cats and horses. In 2024 the company was acquired by Boehringer Ingelheim, which folded the platform into its pet therapeutics research portfolio.

The sole named inventor is Kaspars Tars, a structural biologist at the Latvian Biomedical Research and Study Centre in Riga. His group works on bacteriophages and their virus-like particles, and runs the only laboratory in Latvia capable of solving protein structures by crystallography and cryo-electron microscopy. The same group has applied VLP display to vaccine candidates for Lyme borreliosis, dengue and influenza as well as non-communicable disease targets, which places this canine application inside a much broader line of work on the same structural idea.

The application is a divisional of Australian application 2022291431, itself a divisional of 2017256727, which was the national phase of PCT/EP2017/059977, published as WO 2017/186813. Priority runs back to European application 16167264.7, filed on 27 April 2016. The sequence listing filed with the original international application names Benchmark Animal Health as applicant, so the family appears to have changed hands during prosecution before arriving at Saiba.

Why It Matters

Companion animal dermatology is one of the larger revenue lines in veterinary medicine, and canine atopic dermatitis is the condition that drives it. The two products that reshaped the field, oclacitinib and lokivetmab, both arrived in the mid-2010s and both require repeat administration, daily in the first case and every four to eight weeks in the second. A therapeutic vaccine that produces months of endogenous antibody from a small number of injections attacks the cost and compliance problem rather than the efficacy problem, which is a different commercial argument from the usual one about being more effective than the incumbent.

The underlying science is a deliberate inversion of how vaccines are normally understood. Conventional vaccines teach the immune system to recognise something foreign. This one teaches it to attack something it already carries, and the virus-like particle is the device that makes that possible: geometry rather than chemistry does the work, because tolerance is broken by dense repetitive presentation of the antigen rather than by any adjuvant property of the particle. The same trick is being pursued in human medicine against targets including IL-31 itself, and veterinary applications often move first, because the regulatory path is shorter and the ethical calculus around modifying immune tolerance is assessed differently.

The filing history is a long defensive chain. A 2016 European priority, an international filing in 2017, an Australian divisional in 2022 and another in 2026, all still pending. Divisionals taken this far out usually mean a platform rather than a single product: the same particle, the same coupling chemistry and the same tolerance breaking argument can be applied to a different antigen, and keeping claims alive on the first one preserves room to describe the next.

Related Concepts

• Virus-like particle – the empty viral shell that gives the vaccine its repetitive antigen display.
• Cucumber mosaic virus – the plant virus whose coat protein forms the core particle.
• Interleukin 31 – the itch cytokine the induced antibodies are meant to neutralise.
• Lokivetmab – the marketed anti-IL-31 monoclonal antibody this approach is an alternative to.
• Oclacitinib – the daily oral JAK inhibitor that dominates current treatment of the condition.
• Immune tolerance – the mechanism the vaccine is designed to overcome in order to raise antibodies against a self protein.

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AU 2026202093 was published in the Australian Official Journal of Patents on 9 April 2026 and is open for public inspection. Patent applications represent inventions that are sought to be protected and do not necessarily reflect commercially available products.