ROLE OF CD4+T CELL SUBSETS IN THE DETERMINATION OF THE CLINICAL OUTCOME OF JAPANESE ENCEPHALITIS INFECTION

Japanese encephalitis is the most common arthropod-borne human encephalitis in the world. JEV clinical outcomes vary from complete recovery to recovery with neuropsychiatric sequelae to death. Contribution of T cells to the control and immunopathology of JEV infection has been reported in various studies. CD4⁺ T cells were found to be major T cells that has role in protection as well as affecting the clinical outcome in murine Japanese encephalitis model. Role of the CD4⁺ T cells subset in determining outcome of JEV infection is incompletely understood. Therefore, we sought to determine how quantitative difference in CD4⁺ T cell subsets influences JEV infection outcome. A total of 544 Acute Encephalitis Syndrome (AES) cases were admitted in ICU and AES ward of Kushinagar District Hospital during a period from Aug 2013 to Dec 2015. A diagnosis of JEV infection was based on clinical symptoms and anti-JEV IgM antibody in the acute phase cerebrospinal fluid (CSF) and serum samples measured by IgM antibody capture (MAC)-ELISA. Blood samples were drawn, and flow cytometry analysis was performed. The outcome was recorded as death, recovered, recovered with sequelae. Percentage of T cell subset CD3⁺ T cells, CD4⁺ IFNγ⁺ (Th1), CD4⁺ IL-4⁺ (Th2), CD4⁺ IL-17⁺ (Th17) and CD4⁺CD25^high+Foxp3⁺ T reg cells were analyzed and compared between patients with different outcome. CD4⁺ Th1 percentage was found to be significantly in recovered patients when compared to other disease groups. A positive correlation was observed between GCS and Tregs cells (r=0.34 P=0.002). We conclude that CD4Th1 might be associated with recovery after JE infection. Treg cells expansion during JEV infection may lead to improvement in neurological manifestation.