University of Khartoum

Evaluation of Immune Response of Selected Sudanese Population To A and C Meningococcal Polysaccharide Vaccine During Meningitis Epidemic in Sudan

Evaluation of Immune Response of Selected Sudanese Population To A and C Meningococcal Polysaccharide Vaccine During Meningitis Epidemic in Sudan

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Title: Evaluation of Immune Response of Selected Sudanese Population To A and C Meningococcal Polysaccharide Vaccine During Meningitis Epidemic in Sudan
Author: Ahmed, Adil
Abstract: The present study was carried out in greater Khartoum the capital of the Sudan. The study was undertaken during group A meningococcal epidemic 1999. This study evaluated the immune response ofselected Sudanese population to A and C meningococcal polysaccharide vaccine during serogroup A meningococcal epidemic in Sudan, and compared the immune response of Sudanese adults and North American adults to the unconjugate meningococcal polysaccharide vaccines. Convenient blood samples were collected from one hundred thirty seven healthy Sudanese individuals pre-immune ,10 days, one month, and one year after vaccination with A+C meningococcal polysaccharide vaccine in the period between May 1999 and June 2000 Serum samples collected from healthy American adults pre-vaccination and one month after vaccination with A, C, Y, W135 polysaccharide vaccine were stored at -80 Cº used in this study. The sera wereinvestigated using different laboratory methods to measure the concentrations of antibody level and antibody activity, including Radio Antigen Binding Assay (RABA), Enzyme Linked Immuno Sorbent Assay (ELISA), and Bactericidal assay. Serum group A anticapsular antibody concentrations measured by RABA had statistically significant difference, from the pre-immunization and 30 days postimmunization sera for the different Sudanese age groups (P<0.001, P<0.005, ANOVA), whereas the 10 days and one year after immunization were not statistically different (P=0.1, P=0.9, ANOVA), the same results were occurred when the antibody concentrations were measured by ELISA technique (P<0.001, P<0.02, ANOVA),(P=0.13, P=0.24, ANOVA). The correlation between RABA vs ELISA in Sudanese individuals of different age groups was good for pre-immunization and 30 days post-immunization points(R 2 =0.93, R 2 =0.74) but not remarkable at 10 days or one year after vaccination with A+C meningococcal polysaccharide vaccine for subjects 3-10 years( R 2 =0.62). Whereas age group > 10 years for the Sudanese subjects showed the same correlation (R 2 =0.75, R 2 =0.69, R 2 =0.79, R 2 =0.69). Before immunization, , serum group A anticapsular antibody concentrations were 10-fold higher in adults, and 4-fold higher in the youngest and teenagers age group from the Sudan than adults from North American (geometric means of 29 µg/ml and 13 µg/ml, respectively, vs. 3 µg/ml, P<0.001). Seventy-five percent of the Sudanese had serum bactericidal titers that correlate with protection (>1:128). Nearly all Sudanese with low antibody levels developed protective bactericidal antibody responses after vaccination, and the magnitude of the anticapsular antibody responses of the Sudanese was similar to that of the immunized North Americans, The high levels of naturally-acquired antibody in the Sudanese may reflect widespread exposure to group A N. meningitidisduring the epidemic and due to difficulties of instituting immunization before exposure occurs
Description: 139 page
URI: http://hdl.handle.net/123456789/8049
Date: 2015-04-01


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