Features of IgG-antibodies production to individual Cytomegalovirus proteins in various eye diseases (age-related macular degeneration and central serous chorioretinopathy)
Age-related macular degeneration (AMD) and central serous chorioretinopathy (CSC) are diseases targeting the posterior segment of the eye that often lead to lowered visual functions. Pathogenesis of such disorders largely remains unclear. Among the risk factors of developing chronic inflammation, various microorganisms are considered, particularly Cytomegalovirus (CMV ). The study was aimed at analyzing the humoral response to individual viral proteins during chronic and reactivated CMV infection in AMD and CSC patients. Materials and methods. 104 CMV-seropositive patients were enrolled in the study including 75 AMD and 29 CSC subjects. IgM- and IgG-antibodies specific to CMV late viral antigens as well as IgG antibodies against the main non-structural immediate early (IE) antigen were evaluated by ELISA. IgG antibodies to individual CMV phosphoproteins such as the main non-structural immediate early protein (IE), the DNA-binding phosphoprotein pp52, and the tegument phosphoproteins (pp150, pp65, and pp28) were assessed by using Line-Immunoassay: recombinant antigens containing immunodominant protein fragments derived from viral antigens (p52, p150, p65, p28) were used. Positive (bands 2+) and strongly positive (bands 3+) data were only used for analysis. Results. It was shown that in both groups patients with chronic CMV infection had comparable rate of detected antibodies specific to individual antigens. The level of seropositivity to CMV р150 and р65 was significantly higher than that to CMV р52 and р28 (p < 0.05). Patients with AMD compared to patients with CSС had significantly higher moderate positive response (2+) to all the antigens examined. Upon reactivation of chronic CMV infection in AMD patients, the level of seropositivity to all antigens was increased, the number of cases with an intensely positive response to individual antigens was elevated, but patients with moderate positive response still prevailed. However, reactivation of chronic CMV infection was observed only in 6 CSС patients, allowing to perform no comparative analysis between these two groups. Conclusion. The main difference between CMV-chronically infected patients with AMD and CSC was not found at the level of seropositivity to individual CMV recombinant antigens, but rather in magnitude of antibody production so that AMD patients in comparison to CSC patients displayed moderate antibody production (bands 2+). A marked difference was related to the level of antibodies against CMV p150: AMD patients showed moderate antibody response (bands 2+), whereas CSC subjects dominated with strong positive response (bands 3+) (p < 0.05). It seems that moderate antibody production to recombinant CMV antigens examined in AMD patients occurs due to a weak expression of such viral antigens during chronic infection, resulting in long-term maintenance of antigenic stimulation leading to prolonged inflammation.