Isolation of St. Louis encephalitis virus from the peripheral blood of a human subject

Abstract

Summary A filtrable virus has been isolated from the blood of a patient whoseclinical manifestations were suggestive of a virus infection with minimal central nervous system involvement. The infectious agent isolated is neutralized by serum of a rabbit immunized to a known strain (Hubbard) of St. Louis encephalitis virus. During the clinical course the patient developed increasing antibody titer to the newly isolated virus and to known St. Louis encephalitis virus (Hubbard). Two criteria for the diagnosis of a virus disease have been satisfied; namely, isolation of an infectious agent from the patient, and development during the course of clinical illness of type-specific humoral antibodies. This work represents the first instance of the isolation of the St. Louisencephalitis virus from a human subject during life. It is the fourth instance in which the St. Louis virus has been isolated from natural sources, the first being the initial isolation from human brain tissue taken at autopsy, 19, 20 the second from mosquitoes collected in nature during an epidemic, 21 the third from the bodies of chicken mites collected in nature during a nonepidemic period. 22 The intraperitoneal injection of young mice with relatively large inoculamay prove to be generally applicable for the isolation of virus, especially for the detection of small amounts.