Measles virus-specific immunoglobulin G subclass response in serum and cerebrospinal fluid.

Background: While many previous studies have focused on the impairment in the cellular immunity during measles virus infection, to date, a limited amount of data is available concerning the virus-specific IgG subclass response during measles virus infection.
Objective: The purpose of this study is to analyze the measles virus infection on the basis of virus-specific IgG subclass (G 1 and G 3).
Study Design: Frozen-stored, serum and/or cerebospinal fluid samples from three groups of patients were tested retrospectively; Group 1 comprised 14 patients with measles primary infection, group 2, ten patients with reinfection/vaccine failure, and group 3, seven patients with subacute sclerosing panencephalitis. The method used was a modified ELISA method utilizing the Enzygnost IgG detection kit with mouse-monoclonal antibodies (clone HP6091 for IgG 1 and clone HP6050 for IgG 3). Avidity testing for each subclass IgG was also performed for selected samples by means of an 8 M urea-denaturation method.
Results: In group 1, the IgG 3 could be detected in serum within 7 days from the onset of rash more frequently than IgG 1. In the cases of group 2, both subclasses were detected in very acute phase serum samples. In these cases, the IgG 1-specific avidity was always higher than that of IgG 3. In group 3, the subclass IgGs detected in the cerebrospinal fluid had a lower avidity than those in the serum.
Conclusions: Our results suggested that in measles virus infection, like other viral infections, the IgG 3 response normally occurs before the IgG 1 response, and plays a major role in the acute phase immunity during the primary infection, while the IgG 1 plays a major role in the maintenance of immunity. Continuously produced IgG 1 and IgG 3 in the central nervous system in cases of subacute sclerosing panencephalitis may be derived from cell populations different from those in the blood.