ABSTRACT
Bancroftian filariasis is a major public health problem affecting about 120 million people all over the world. Immunoprophylaxis may serve as an additional adjunct along with chemotherapy and anti larval measures for successful filaria control. Circulating filarial antigen fraction (CFA2-6) containing 43 kDa antigen and adult Brugia malayi sodium dodecyl sulphate (S DS) soluble antigen fraction BmA-2 with a 120 kDa molecule were earlier shown to be reactive with endemic normal sera by immunoblotting and indirect ELISA techniques. BmA-2 was found to be highly cross reactive with CFA2-6. Sera raised against both the antigen fractions showed about 9 0 % cytotoxicity to the parasites in the presence of jird peritoneal cells in in vitro as well as by in situ micropore chamber implantation technique. Further in in vivo studies using animal model, jirds CFA2-6 and BmA-2 could induce about 90% protection to infection in immunized animals. In passive transfer studies of immunity it has been observed that BmA-2 induced protection is mainly antibody mediated.
ABSTRACT
Detection of filarial antigen in blood or urine samples would provide an accurate indication of active infection. The absence of a simple, well established animal model and limitations in getting the required amount of parasite material from human sources have been the main obstacles for the diagnosis ofWuchereria bancrofti infection. An inhibition ELISA has been developed for detection of filarial antigen using a partially purified Brugia malayi mf ES antigen (BmE DE1) and its affinity purified antibodies. Filarial antigen was detected in the sera of 88% of microfilaraemic, 60% of chronic filarial, 17% of endemic normal and none of the non-endemic normal subjects. The sensitivity and specificity of the assay were 88% and 89% respectively. Moreover, undiluted urine samples from 82% of microfilaraemic and 17% of endemic normal, but none of the non-endemic normal samples showed the presence of filarial antigen.With the limitations on the availability of sufficient homologous parasite materials, the inhibition ELISA using BmE DE1 and anti BmE DE1 antibodies shows promise for the detection of active infection in bancroftian filariasis in man.Moreover, its detection in urine makes it more possible to test patients in field areas.
ABSTRACT
Different antigen preparations, viz. excretory-secretory antigen (ES Ag), phosphate buffer saline soluble antigen (PBS-S Ag) and sodium dodecyl sulphate soluble antigen (SDS-S Ag) of M. tuberculosis (M.tb) H37Ra strain along with tuberculin purified protein derivative (PPD) were employed in stick indirect ELISA to detect IgG antibodies in sera of sputum positive pulmonary tuberculosis cases. Sera from healthy individuals and individuals with diseases other than tuberculosis (cross-reacting diseases) were used as controls. ES antigen and PPD showed higher antibody titres in tuberculosis cases (GMT-1378 each) compared to PBS-S Ag (GMT-454) and SDS-S Ag (GMT-974). Thereafter, an extensive study was done analysing higher number of sera in each group for the detection of tuberculous IgG antibodies using ES Ag and PPD. The ES Ag showed better sensitivity (87%) and specificity (85%) compared to the sensitivity (73%) and specificity (78%) achieved with PPD. The ES Ag also showed higher IgG antibody titre (GMT-1068) than PPD (GMT-721). From the present study it can be envisaged that ES Ag has high diagnostic potential in tuberculosis.
Subject(s)
Antibodies, Bacterial/blood , Antigens, Bacterial/immunology , Enzyme-Linked Immunosorbent Assay , Humans , Immunoglobulin G/blood , Mycobacterium tuberculosis/immunology , Sensitivity and Specificity , Sputum/microbiology , Tuberculin/immunology , Tuberculosis/bloodABSTRACT
Urinary filarial antigen isolated from urine samples of microfilaraemic patients was analysed for its antigenic activity by immunoblotting and enzyme linked immunosorbent assay techniques. SDS-PAGE fractionation of urinary filarial antigen showed 11 protein bands, of which two showed reactivity with immunoglobulin-G fraction of filarial serum immunoglobulin in immunoblotting. Antigenic analysis of SDS-PAGE fractions of urinary filarial antigen by inhibition enzyme linked immunosorbent assay using filarial serum immunoglobulin-G and Wuchereria bancrofti microfilarial excretory-secretory antigen revealed 3 fractions, numbers 5, 6 and 9 with significant activity. In indirect enzyme linked immunosorbent assay using fractions 5 and 6, filarial immunoglobulin-G antibody was detected in about 90% of microfilaraemics, 80% clinical filariasis and 20% of endemic normal individuals. Further, there was no phosphorylcholine epitope in these fractions. Fractions 5 and 6 can be a candidate antigens for the immunodiagnosis of filariasis.
ABSTRACT
The role of excretory-secretory antigens in inducing immunity in the host against Brugia malayi microfilariae and infective larvae was studied by in vitro antibody dependent cell-mediated reaction as well as in vivo inoculation of filarial parasites within a microchamber in the host. The immune sera of jirds raised against Brugia malayi microfilarial and infective larval excretory-secretory antigens (Bm Mf ESA and Bm L3 ESA) promoted the adherence of peritoneal exudate cells to Brugia malayi microfilariae and infective larvae in vitro and induced cytotoxicity to the parasites within 48 h. The anti Bm Mf ESA serum was more effective than anti Bm L3 ESA serum in inducing cytotoxicity to microfilariae and both antisera had a similar cytotoxic effect on infective larvae. In the microchambers implanted in the immune jirds, host cells could migrate and adhere to the microfilariae and infective larvae and kill them within 48–72 h. Further, Mastomys natalensis immunized against Bm Mf ESA and L3 ESA generated a high degree of protective response against circulating microfilariae. These results suggest that excretorysecretory antigens are effective in inducing resistance against filarial parasites and thus have potential in immunoprophylaxis.