Measles antibodies in nasal secretions and sera of children with measles.

Measles antibodies were determined, in the course of measles, in sera and nasal secretions of 54 and 27 children, respectively. The examinations were performed on the 3rd or 4th day (1st period) and between the 10th and 14th day (2nd period) after onset of rash in both sera and nasal secretions and after 25 to 60 days (3rd period) in sera only. Geometric mean titres of antibodies in sera determined by haemmagglutination inhibition (HI) and neutralization tests in the 1st period were 126.3 and 115.3 respectively. For the 2nd period the respective figures were 318.4 and 396.1 and for the 3rd period--388.0 and 445.6. Fractionation on Sephadex G-200 of sera from the 1st period revealed HI and neutralizaing antibodies associated mainly with the IgM serum globulin class. Measles HI and neutralizing antibodies were also found in nasal secretions of all 27 children, but their titres were much lower than in serum. The antibodies determined by indirect immunofluorescence in nasal secretions were associated with IgA in 26 and with IgG immunoglobulin in 15 of the 27 subjects. No IgM antibodies were found.