new application of ELISA for the diagnosis and study the prevalence of pneumococcal pneumonia cases in children

An ELISA was set up in this work using the whole-cell pneumococcus as coating antigen for the detection of specific pneumococcal antibody[ies] as a marker for the diagnosis of pneumococcal pneumonia cases among children. Serum samples [31] were collected from cases and matched control subjects. The reliability of the test was ensured by repeating the test of the same sample in different settings, by testing second sample of the same patient at different time and by including quality control of each dilution of each tested serum sample and each reagent used in this assay. Using blood culture as the gold standard test for the diagnosis of these cases, sensitivity [90%-100%] and specificity [80%-90%] of this technique were discussed. This assay is an easy technique and does not need any special reagents, equipment or skills. ELISA of this work could be considered as a diagnostic discrimination test for the diagnosis and for the study disease frequency survey of pneumococcal pneumonia cases among children in rural or urban communities

Preparation purification and characterization of neisseria meningitidis group a capsular polysaccharide tetanus toxoid conjugates

Conjugation of Neisseria meningitidis A Capsular polysaccharide [CPS] to tetanus toxiod [TT] was aimed at in this work, with the intention of developing a new vaccine which may be more protective, specially to the age group below 18 months. The CPS was prepared and applied to sepharose CL-48 column. Fractions were collected and monitored for their carbohydrate content. They were divided according to their Kd into two pools [low and high molecular weight pools]. Tetanus toxoid was applied to sephacryl S-300 column and fractions were pooled into three pools. The second pool, having a molecular weight of 150 KD, as determined by SDS-PAG was used as the protein carrier. Conjugation was carried out, using cyanogen bromide activated, adipic acid dihydrazide derivative of the CPS. Binding to TT was achieved by a carbodiimide-mediated reaction. The obtained high and low molecular weight conjugates were subjected to gel filtration on sepherose CL-4B column, and the carbohydrate and protein content in the fractions were monitored. In the low molecular weight conjugates, there was a shift in the elution pattern the left. This indicates an increase in the molecular size. Fractions were pooled and the pools were tested for their antigenicity, against a standard horse anticapsular polysaccharide antibodies. The ratio of carbohydrate to protein in the conjugate was also determined

Antibody response against neisseria meningitidis group A capsular polysaccharide in mice receving meningococcal a capsular polysaccharide-tetanus toxoid conjugates

C 57 BL/6J Mice were used to study the antibody response against neisseria meningitidis group A capsular polysaccharide [CPS]. Four groups [8 mice each] were injected twice subcutaneously [SC] with a 2 microgram equivalent of meningococcal A capsular polysaccharide, and a fifth group received an equal volume of saline diluent and served as the control group. ELISA was done using tyraminated CPS preparation to coat the polyvinyl chloride flexible plates. Results showed that the postimmunization sera of the groups receiving either of the previously prepared high and low molecular weight conjugates, or capsular polysaccharide added to tetanus toxoid had, a better antibody titer than their preimmunization serum. The control group had no change in antibody response, while the group receiving the standard CPS vaccine showed vary little increase. However, only the group receiving the low molecular weight conjugate showed a significant increase in titer as compared to the group receiving CPS added to tetanus toxoid. The high molecular weight conjugate group did not show this difference. Furthermore, the sera of low molecular weight conjugate group are partiaty inhibited when preincubated with CPS before the ELISA assay. The results showed that the low molecular weight conjugate is a better vaccine against meningococcus A than either the CPS alone, CPS added to tetanus toxoid or the high molecular weight conjugate

suggested vaccine formulation for the control of pneumococcal meningitis in Egypt

Mortality rates of pneumococcal meningitis ranges from 13-60% in different parts of the world. Reports of pneumococci with multiple antibiotic resistance add urgency to the need for developing means of primary prevention. A 14-valent pneumococcal vaccine was licensed in 1977, and a 23-valent pneumococcal vaccine in 1983. In the present work 131 strains of pneumococci isolated from meningitis cases in Egypt were identified and serotyped by Quellung reaction. The most frequently isolated serotype was serotype 1 [32%]. Sero-types 6A, 9L, 12A, 19A and 29 were next in prevalence. The age groups 0-18 years were the most frequently affected groups [79%] and over 18 years of age were only 21% of total cases. A vaccine formulation is suggested to have a coverage rate against pneumococcal meningitis cases of 79.3% and 89.3% of a proposed 14-valent vaccine and 23-valent vaccine versus to coverage rate of 48% and 54% of 14-valent and 23-valent International vaccines respectively. According to the age distribution of cases and the isolated serotypes a vaccination could be recommended during the first two years of age in order to protect the most frequently infected groups