Effects of Cyclophosphamide on the Antibody Response in Mice Immunized with Japanese Encephalitis Virus Vaccine

Abstract

A formalin-inactivated Japanese encephalitis virus (JEV) vaccinewas inoculated into mice treated with cyclophosphamide (CY) at various intervals, and its effectson the antibody response were investigated. CY treatment in a few days after immunization delayed the appearance of the HI and NT antibodies in sera and decreased the maximum levels of the antibody titers.As for the immunoglobulin classes of the HI antibody, however, the pattern that IgM appeared first then IgG became predominant was the same as that observed in non-CY-treated mice.
In another experiment, live JEV was inoculated into CY-treated mice after immunization with formalin-inactivated vaccine.A few mice died of encephalitis after a single injection of CY and more mice after double injections suggesting that the delayed antibody response at the early stage of JEV infection might lead to serious consequences in experimentally infected animals.
After a single injection of CY, peritoneal exudate cells (PEC) decreased in number during day 4 through day 7, and random migration of PEC was suppressed during day 1 through day 8 suggesting that macrophages were also damaged by CY at a dose of 240μg/g of mouse body weight.