Full-Length Infectious cDNA Clones of Tick Borne Flavivirus

The tick-borne encephalitis virus complex of flavivirus family includes tick-borne encephalitis (TBEV), Kyasanur forest disease, Langat, Louping ill, Negishi, Omsk hemorrhagic fever and Povassan viruses. These viruses are endemic throughout most of the Northern Hemisphere and except for Langat, cause human disease of varying severity that can have mortality as high as 20 to 30%. Tick-borne encephalitis remains a pressing public health problem in Eastern Europe and Russia, where 9,000 to 12,000 patients are diagnosed annually and there is a need for a vaccine which can prevent this disease.

This invention relates to an infectious full length Langat virus cDNA which has been successfully constructed and can be used to further attenuate this naturally attenuated tick-borne flavivirus. This full length Langat virus can be used as a live attenuated virus vaccine for the prevention of severe, often fatal disease caused by its more virulent tick-borne flavivirus relatives such as tick-borne encephalitis virus.