ANTIBODIES TO PARVOVIRUS B19 NS-1 PROTEIN IN INFECTED INDIVIDUALS

Human parvovirus B19 is the aetiological agent of the common childhood disease erythema infectiosum (fifth disease). The infection is usuall y benign and self-limiting, but in adults cases of severe arthritis wh ich may persist for years have been reported. Neutralizing antibodies directed against the structural proteins are usually produced shortly after the infection. The immune response against the third major prote in, the nonstructural protein NS-1, of parvovirus B19 has not been cha racterized so far. We cloned and expressed the full-length NS-1 protei n and fragments thereof in Escherichia coli. The purified recombinant proteins were used to investigate the presence of antibodies to the NS -1 protein in sera from patients with parvovirus B19 infection. Specif ic antibodies could be detected in sera from patients suffering from s evere parvovirus B19-associated arthritis using Western blot analysis and an ELISA. Sera from patients with acute or past infection without complications did not contain detectable levels of immunoglobulin to N S-1. The use of subfragments of the NS-1 protein allowed localization of the antigenic domains in the carboxy-terminal region of the protein .