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On the horizon: A single-dose solution for leptospirosis?

It’s possible.

According to a new study in hamsters, scientists have designed a single-dose universal vaccine that could protect against many forms of Leptospira bacteria.

Leptospirosis is a life-threatening disease with flu-like symptoms that’s caused by bacteria of the genus Leptospira. The disease is spread in the urine of animals such as dogs, livestock, and wildlife. Humans can contract leptospirosis when they come in contact with urine-contaminated water and soil.

Although vaccines are available for animals, it only protects against a few types of the disease-causing Leptospira bacteria.

Previous research has shown that inactivating a Flagellar-coiling protein (FcpA), which is necessary for Leptospira mobility, can stop the bacteria from infecting hamsters. More importantly, when these animals were exposed to the mutant bacteria, they didn’t get sick—and they didn’t develop the disease.

The researchers decided to test whether bacteria lacking the FcpA protein could be used as an attenuated vaccine (a vaccine that contains a weakened form of the live bacteria that causes the disease that is weak enough to be harmless but still strong enough to train the immune system to produce long-lasting antibodies).

The result: A single dose of the vaccine was enough to prevent hamsters and mice from dying of leptospirosis.

NEWStat reached out to lead author Elsio Wunder, PhD, MS, DVM, a research scientist in the Department of Epidemiology of Microbial Diseases at Yale University’s School of Public Health, to find out more.

NEWStat: Dogs require an initial two doses of the leptospirosis vaccine three to four weeks apart and an annual revaccination. How effective is the single-dose vaccine you and your colleagues are working on?

Elsio Wunder: A single dose of our attenuated vaccine induced an immune response strong enough to protect vaccinated animals against disease and death caused by leptospirosis infection. On mice models, it showed also that it can protect animals against colonization, which could potentially stop the spread of the disease.

NEWStat: How does your vaccine differ from those that are currently available?

EW: Our study showed that the immune response induced by our attenuated vaccine is against leptospiral proteins, a contrast from the current vaccines that [provide] immunity against the lipopolysaccharide of the bacteria. Since proteins can be conserved among different species, this advantage is evidenced by the ability of our vaccine model to protect against different species of pathogenic Leptospira.

NEWStat: Is this a vaccine that could be used for dogs?

EW: Definitely. This vaccine has the potential to be used for dogs and other animals.

NEWStat: What’s the next step in your research?

EW: We are currently working to determine how effective this vaccine is in dogs and other animals. We recently partnered with a veterinary company to make this a product available for animals in the near future.

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