Protective immunity spectrum induced by immunization with a vaccine from the TBEV strain Sofjin

Area of Science:

• Virology
• Immunology
• Vaccinology

Background:

• Tick-borne encephalitis (TBE) is a significant public health concern in Eurasia, with up to 10,000 annual cases.
• TBE virus (TBEV) encompasses diverse subtypes and variants, necessitating broad-spectrum vaccine protection.
• Current commercial TBE vaccines utilize inactivated antigens from European or Far-Eastern strains.

Purpose of the Study:

• To evaluate the protective efficacy of the TBE vaccine Moscow against a wide range of TBEV strains and related viruses.
• To assess the influence of vaccination parameters on the vaccine's protective effect in vivo.
• To determine the correlation between viral genetic distance and vaccine-induced protection.

Main Methods:

• Utilized a panel of 14 TBEV strains representing all known subtypes and variants, alongside Omsk hemorrhagic fever virus (OHFV) and Powassan virus.
• Assessed antibody titers in immunized mice using plaque neutralization tests.
• Conducted in vivo experiments to demonstrate protective effects against viral challenge, varying vaccination intervals, challenge doses, and challenge timing.

Main Results:

• TBE vaccine Moscow induced protective antibodies against all tested TBEV strains and OHFV.
• Vaccine efficacy was demonstrated in vivo, showing protection across varied vaccination and challenge parameters.
• No protection was observed against Powassan virus, despite a 0.008-0.069 E protein amino acid distance.
• The E protein amino acid distance did not decisively impact vaccine protection in vitro or in vivo.

Conclusions:

• TBE vaccine Moscow offers a broad protective immune response against diverse TBEV variants and OHFV.
• Vaccine efficacy is robust and not significantly affected by variations in vaccination schedules or challenge conditions.
• The vaccine's protective scope is limited against antigenically distinct viruses like Powassan virus.