Blood brain barrier disturbance and immunoglobulin G levels in the cerebrospinal fluid of the mouse following peripheral infection with the demyelinating strain of Semliki Forest virus.

Immunoglobulin G and albumin levels have been measured in the cerebrospinal fluid and serum of Swiss A2G mice following single intraperitoneal inoculation of Semliki Forest virus. This strain of virus used causes a meningoencephalitis followed by immunologically-mediated demyelination. By the use of the levels of immunoglobulin G and albumin in cerebrospinal fluid and serum to calculate the cerebrospinal fluid: serum ratios and the cerebrospinal fluid immunoglobulin G index, it has been shown that the blood-brain barrier breakdown is mild and restricted to within the first 7-8 days after virus inoculation when the inflammatory response is maximal. Immunoglobulin G index provides a measure of synthesis of immunoglobulin G within the blood-brain barrier. Synthesis has been shown to occur from day 10 onwards up to at least day 61 following infection. Arboviruses are known to persist in central nervous system tissue and it is suggested that a continuing immune response within the central nervous system occurs and is perpetuated by persisting virus. Because of the mode of replication of Semliki Forest virus it is also possible that some of the immune response is directed against central nervous system components.