Measles virus protein-specific IgM, IgA, and IgG subclass responses during the acute and convalescent phase of infection

The availability of new generation serological assays allowed re‐evaluation of the antibody response to measles virus. IgM, IgA, total IgG, and IgG subclass responses were studied to the three major immunogenic measles virus proteins: the fusion protein (F), haemagglutinin (H), and nucleoprotein (N). Plasma samples were obtained from clinically diagnosed measles cases (n = 146) in Khartoum (Sudan) within a week after onset of the rash. Convalescent phase samples were collected from 32 of 117 laboratory‐confirmed measles cases at different time points after onset of rash. Glycoprotein‐specific IgM, IgG, and IgA antibody levels correlated well to the N‐specific response. For IgG and IgA, responses to F were higher than to H. IgA antibody levels were undetectable in about one third of the laboratory‐confirmed cases during the acute phase, but positive in all patients tested 1–4 weeks after infection. IgM levels declined rapidly and were lost 3–6 months after infection. IgA levels declined slowly during the first year but did not return to background levels during the subsequent 2 years. IgG avidity maturation was detected during a 3–6 month period after infection. The predominant IgG subclasses during the acute phase were IgG1 and IgG3. The latter was lost in the convalescent phase, while the IgG4 isotype showed a slight rise afterwards. Interestingly, acute phase IgG3 and IgA responses were associated, and were only detected in samples with high IgG. This study provides a comprehensive perspective on the antibody response to wild‐type measles virus infection. J. Med. Virol. 72:290–298, 2004. © 2004 Wiley‐Liss, Inc.