Characteristics and mechanisms of isolated rubella virus, strain JR23: Infection of the central nervous system of BALB/c mice
ABSTRACT To investigate the correlation between rubella virus (RuV) antigen in peripheral lymphocytes, the immune status and RuV infection in the central nervous system (CNS).
BALB/c mice were used as a model and treated with immunoaffecting medicines. Then, the mice were infected with RuV via the abdominal cavity, and the antigen level in peripheral lymphocytes was examined 1, 3, 7 and 14 days postinfection. RuV in the CNS was detected by immunohistochemical methods. BALB/c mice were given dexamethasone and cytoxan before infection with the RuV JR23 strain. Immune functions and RuV invasion of the CNS were assayed on day 21 postinfection via the abdominal cavity, and their relationship was analyzed.
The mean antigen detection rates at different times were 3.1, 4.1, 9.6 and 2.4%, respectively, in the dexamethasone group, and 14.2, 12.7, 9.9 and 3.1%, respectively, in the cytoxan group. In the group without any intervention, the detection rates were 4.63, 10.25, 6.88 and 1.75%, respectively. The antigen detection rates in peripheral lymphocytes among the three groups 24 h postinfection were significantly different (F = 0.0317, p < 0.05). Comparisons between groups showed that antigen detection rates in the cytoxan group were much higher than those in other groups, but there was no difference between the dexamethasone and control groups. The animals with persistent presence of antigen were much more susceptible to cerebral infection than those with short-term presence (p < 0.001). T cell functions of the cytoxan group were significantly lower than those of other groups (p < 0.05), as detected by the MTT method. Infection rates of the dexamethasone, cytoxan and control groups were 60, 90 and 50%, respectively. Cell immune functions of the mice with CNS infection were obviously worse than those of the mice without CNS infection (p < 0.001). RuV-specific antibodies were assayed in all groups by ELISA and the results showed that there were no significant differences among groups (p < 0.05) or between the groups with and without CNS infection.
Cytoxan can affect virus detection rates in peripheral lymphocytes. At the early phase of infection, the persistent presence of RuV in peripheral lymphocytes increases the incidence of CNS infection. RuV infection in the CNS was related to the cell immune situation before specific antibody was produced in the body.
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