New evidence in the fight against TBE

– There is currently no other defense against tuberculosis than protecting oneself from ticks and making sure to get vaccinated, but hopefully the research will lead to a better understanding of how the virus enters the brain, and thus we will find therapeutic treatments for the infected person, says Ebba Rosendahl, a doctoral student at Umea University.

In her thesis in Virology at Umeå University, Ebba Rosendahl studied how the TBE virus interacts with the body’s immune system and what causes the disease symptoms that occur with TBE. Eba Roosendaal and the research group she is part of in the Department of Clinical Microbiology have determined how the virus infects the brains of mice with or without an early immune response.

Brain immune cells

They could then see that in cases where the brain’s immune system could not be activated, completely different parts of the brain were infected, for example the cells that produce cerebrospinal fluid and the brain’s immune cells, microglia. This shows how important the immune system is to those with TBE and provides clues about how it can help the body fight infection.

“It’s about basic research, but it presents a small piece of the puzzle so that in the long term we can beat this pesky virus and possibly create better treatments for people who aren’t lucky enough to be infected,” says Ebba Rosendahl.

In another part of the thesis, the so-called pathogens of the TBE virus were examined. Researchers have discovered that small, naturally occurring changes in the virus’ genome can alter the surface structure of the virus and thus its ability to cause disease. By comparing several closely related TBE viruses, a Swedish variant of the virus was identified that caused unusually severe disease in mice. This virus strain, so far named 93/783, has two unusual changes in its surface protein. The study showed that these changes affected the ability of the virus to infect neurons, cause disease in mice, and how well the vaccine-induced antibodies could neutralize the virus.

some disease

This finding may be a clue as to why some people who contract tuberculosis from tick bites get sicker than others. Researchers don’t yet know how common this newly discovered variant is. The problem for researchers is that once patients seek care for neurological problems caused by the tick-borne TBE virus, the consequences have developed so far that it is difficult to find the underlying virus in a patient.

Because of the dangerous nature of the TBE virus, it may only be handled by trained personnel in specialized biosafety laboratories. This makes some analyzes and methods difficult and time consuming. Because the Umeå researchers are particularly interested in the surface proteins of the TBE virus, a new model system has been developed in one of the subprojects to study these proteins. For this purpose, a relative of the non-hazardous TBE virus to humans, Langat virus, was used, but its surface proteins were replaced by those of the TBE virus.

The resulting virus looks like TBE virus, but behaves like Langat virus in cell culture and in mice. This makes it a very useful tool for studying various aspects associated with the surface structure of a virus, such as the antibody response after vaccination against TBE.

Tick-borne encephalitis, TBE, is a neurological disease caused by the TBE virus. Every year, 300-500 cases of tuberculosis are reported in Sweden alone. The consequences of infection can be very serious and lead to long-term functional impairments.

Ebba Rosendal grew up on a stud farm outside Fagersta in Västmanland. Before coming to Umeå to research viruses, she studied engineering in Lund.