CELLULAR IMMUNE RESPONSE TO OMSK HEMORRHAGIC FEVER AND TICK-BORNE ENCEPHALITIS VIRUS

Bersabeh Tigabu, DVM, Ph.D., T. Juelich, B.S., M. Holbrook, Ph.D.

Department of Pathology, UTMB

Background: Omsk hemorrhagic fever virus (OHFV) and Russian spring-summer encephalitis virus (RSSEV) are tick-borne flaviviruses that cause viscerotropic and neurotropic diseases, respectively. Objective: To examine the interactions between OHFV/RSSEV and splenocytes and bone marrow DC to identify responses that contribute to pathogenesis of tick-borne flaviviruses. Methods: C57BL/6 and Balb/c mice were challenged with 1000pfu RSSEV or OHFV and, for in vitro experiments, bone marrow DC were infected with 1MOI of RSSEV or OHFV. Results: Infection of mice with RSSEV doesn’t significantly affect lymphocyte populations while OHFV infected balb/c mice have decreased T lymphocytes. In vitro infection of bone marrow DC with OHFV/RSSEV did not significantly activate DC maturation markers. Conclusions: The functional maturation of DC in response to OHFV/RSSEV infection is modified, leading to a reduction of the capacity of DC antigen presentation and, consequently, reduced T-cell activation. (Supported by the Western Regional Center of Excellence (U54AI056157).