Peripheral pathogenicity of a Chinese strain (Beijing P3) of Japanese encephalitis virus in immunodeficient and immunocompetent mice

The inoculation of mice with a Chinese strain (Beijing P3) of Japanese encephalitis (JE) virus by peripheral (subcutaneous) route, produced a fatal disease both in immunodeficient adult BL6 nude (nu/nu) mice, and immunocompetent BL6 +/nu and Swiss mice. All the BL6 nu/nu mice (100%) showed morbidity subsequently followed by mortality as against 29% and 63% BL6 +/nu and Swiss mice, respectively. The virus was recovered from the brain and other organs of sick/dead mice. Biphasic viraemia was recorded in BL6 nu/nu mice but primary viraemia only in BL6 +/nu mice. The virus was not detectable in any of the organs during the period between two viraemic phases in BL6 nu/nu mice. Interestingly, the antibodies were detected in the sera of both the apparently healthy and sick BL6 +/nu and Swiss mice from second week post-infection but none in nu/nu mice. These studies indicate that Beijing P3 strain of JE virus produces encephalitis even in immunocompetent mice whose T cell functions are intact.