Besides Lyme or borreliosis, one of the most feared tick-borne diseases is viral encephalitis (TBE). Some of the people who become infected develop very flu-like symptoms that resolve without major problems but develop a rampant neurological disease that can lead to brain swelling, memory loss, and cognitive decline . In Central Europe and Russia, cases are increasing with about 10,000 episodes reported each year.
Current TBE vaccines require three doses spaced two years apart and only provide about five years of protection before a booster shot is required. Furthermore, there is currently no specific treatment for the disease.
Now, a new study published in the Journal of Experimental Medicine reveals a discovery that opens the way to new, more effective vaccines, as well as a possible treatment for viral encephalitis. The work describes a type of antibody capable of neutralizing the virus and that has shown promise in preventing the disease in mice.
Looking for antibodies
The Rockefeller University scientists examined about 800 antibodies obtained from people who had recovered from TBE or had been vaccinated to prevent infection, and selected the most potent, called VH3-48. This type of antibody is capable of neutralizing laboratory-grown TBE virus varieties, as well as other tick-borne diseases , such as Langat, Louping, Omsk hemorrhagic fever, Kyasanur and Powassan forest disease.
The researchers also showed that these powerful antibodies are not common; in fact, most of the antibodies produced by humans exposed to the TBE virus are of inferior quality , and the HV3-48 only appear occasionally. Furthermore, none of the vaccinated patients who participated in the study managed to develop HV3-48. “You would expect the most prevalent antibodies to be the best, but that’s not the case,” explains Marianna Agudelo, lead author. “This could explain how the virus tricks the immune system, misdirecting it to produce inferior antibodies.”
The discovery of VH3-48 offers hope for a more effective TBE vaccine. “Now that we have the structures of these antibodies, we know what to aim for to design more effective vaccines,” explains Michel C. Nussenzweig, director of the Rockefeller Molecular Immunology Laboratory.
Broadly neutralizing antibodies could also provide the first specific treatment for TBE . The test results reveal that TBE-infected mice recover after receiving antibody therapy, although it remains to be seen whether this effect also occurs in humans. “The next step is a clinical trial with the antibodies,” explains Nussenzweig, “perhaps in Europe, where there are many cases, to see if we can improve the symptoms of those with encephalitis.”
