Published 7.3.2024
Text: Janne Tynell
Image: Vastavalo
Editing: Viestintätoimisto Jokiranta Oy

 

In Finland, some 1,000–2,000 cases of epidemic nephropathy are diagnosed each year as a result of exposure to the secretions of virus-carrying bank voles. Typical symptoms of the disease include a high fever, muscle pain and kidney symptoms. Up to every second patient needs in-patient care at a hospital for an average of five days, which means major costs for public health care.

Epidemic nephropathy is caused by the Puumala virus, a hantavirus with wild bank voles as its natural carriers. In bank voles, the infection is highly common and symptomless. The virus is secreted in urine, stools and saliva. Humans catch the infection typically by inhaling dust that is contaminated with vole secretions, for example, when cleaning up their summer cottages or outbuildings. The Puumala virus does not spread from one human to another.

 

Bait vaccination for small animals

Since there is no vaccine approved for human use, the prevention of epidemic nephropathy is limited to precautionary measures that reduce the risk of exposure. The current research project aims to find out if the incidence of epidemic nephropathy can be reduced by preventing infections in wild bank voles. Especially in the neighbourhood of human communities, bait vaccination might provide an effective strategy for reducing infections.

Bait vaccination of wild animals has been successfully applied to prevent rabies, but the method has not yet been utilised against other zoonotic pathogens. In the bait vaccination against rabies, the bait includes an ampoule containing the virus vector-based vaccine. When an animal bites the bait, the ampoule will break and release the vaccine. The baits are rather sizable and their preparation process is laborious, so the use of this method for small animals or species with large population sizes is challenging. There is, however, a demand for a solution applicable to small animals. Many pathogens with major public-health consequences, such as hantaviruses or bacteria causing borreliosis, are carried by rodents.

 

Nature’s own drug capsule

Ideally, a bait vaccine should be easy to spread out and remain stable in the environment. As an oral vaccine, it should also withstand stomach acids and, preferably, provide protection against an infection through a single dose. Moreover, the vaccine should be easy to produce in large quantities.

Funded by the Sakari Alhopuro Foundation, my research aims at expanding the use of bait vaccination to cover small animals. In collaboration with the Umeå Plant Science Centre, we are developing an oral seed-based vaccine against the Puumala virus. Protection is provided by a vaccine antigen inserted into a plant seed, which serves as a kind of natural drug capsule. The seed itself will protect the antigen from digestive stomach acids and enable it to proceed to the intestine. In the intestinal track, the antigen will be captured by M cells, thus creating a systemic immune response and protection against an infection.

The main advantage in this concept is the stability of the seed in nature, which facilitates the efficient distribution of the seed-based vaccine through extensive bait vaccination campaigns. In addition, seeds are part of bank voles’ natural diet. If my research manages to demonstrate the efficacy of the seed vaccine against the Puumala virus, the same concept could possibly be used for the prevention of other pathogens carried by rodents.

 

 

 

 

PhD Janne Tynell earned his doctoral degree in 2016 with a dissertation concerning the virus-host interaction of the influenza A virus and coronaviruses. During the following six years, he served as a post doc researcher in Sweden, at the Karolinska Institutet in Stockholm and at Umeå University, focusing on stress responses induced by hantavirus infections in host cells and the development of antibody-based medicines against hantavirus infections. Currently, Tynell is working at the Zoonosis Unit, Department of Virology, in the University of Helsinki. His intention is to establish a specific research programme related to the bait vaccination of bank voles.

 

 

 

Links:

https://www.terveyskirjasto.fi/dlk00588 (in Finnish)