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Updated: Aug 20, 2026

An In vitro Model to Study Immune Responses of Human Peripheral Blood Mononuclear Cells to Human Respiratory Syncytial Virus Infection
Published on: December 10, 2013
IgG subclass response to human parvovirus B19 infection
R Franssila1, M Söderlund, C S Brown
1Department of Virology, Haartman Institute, P.O. Box 21, FIN-00014, University of Helsinki, Helsinki, Finland.
Background:
IgG antibodies are essential to immunity against human parvovirus B19 and can neutralize infection both in bone marrow cell cultures infected in vitro and in chronically infected immunosuppressed individuals.
Objectives:
To assess the levels and response kinetics of IgG subclasses towards individual structural proteins of human parvovirus B19.
Study Design:
Subclasses of IgG for capsid proteins VP1 or VP2 were quantified by EIA using monoclonal antibodies in 30 acutely infected and 30 convalescent patients, as well as in 32 remotely infected and 20 non-infected controls.
Results:
In all groups of seropositive individuals the predominant subclass for either structural protein was IgG1. Subclass IgG3 was associated with acute infection. By contrast, IgG4 appeared months after infection, and occurred specifically towards VP1. The ratio of VP1-specific subclasses IgG3 and IgG4 provided a diagnostic test for recent infection with a specificity of 98% and a sensitivity of 97%.
Conclusions:
Comparative measurement of VP1-specific IgG3 and IgG4 is useful in diagnosis. The IgG4 results point to long-term expression of immunologically active VP1 and to T-cell help of T(h)2 type for B-cells recognizing VP1.
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