ROLE OF PREEXISTING VIRUS-SPECIFIC IgG IN PRIMARY DISEASE AND IN REINFECTION WITH RESPIRATORY SYNCYTIAL VIRUS

Abstract. The aim of the study is evaluation of links between presence in blood of specific pre-existing IgG to respiratory-syncytial virus (RSV), clinical course of RSV infection and character specific to RSV humoral immune response in patients of different ages. The antibodies were detected by ELISA using whole RS virus or synthetic peptides corresponded to the selected determinants of the envelope RSV proteins. It was shown that RS specific maternal IgG antibodies passively transferred to babies in utero can circulate in the blood up to 10 months of life. The analysis of paired sera of 45 babies in the age of 1–10 months revealed firstly that presence of maternal IgG specific antibodies to the conservative B-cell immunogenic determinants of the F-protein (amino acids 221–232) and/or the G-protein (amino acids 152–164 and 184–198) is coupled with more high morbidity of primary RSV infection (89% versus 56%, p = 0.023), and also with more high frequency of complicated by bronchus obstruction course of the disease (81% versus 20%, р = 0.001) in compare with babies who were serologically negative to the maternal determinants specific antibodies. The correlation analysis has shown that the high presence of maternal determinant-specific IgG in the blood in babies till 10 months of life is associated in the case of primary infection with disbalance of humoral anti-viral immune response: intensive synthesis of serum RSV IgA. This is evidence of complicated course of infection with simultaneous suppression of response to RSV specific IgG. As opposed to the primary RSV infection in patients older than 3 years (n = 121) it was not detected links between anamnestic determinant-specific IgG synthesized by own immune system as the results of previous disease episodes and synthesis of anti-RSV IgG, IgM, IgE and IgA in RSV re-infections. In the contrast to babies in more older patients the feedback connection between level of pre-existing determinant-specific “memory IgG” and diagnostics of RSV infection has been established.