IgG subclass responses to proinflammatory fraction of Brugia malayi in human filariasis.

Background & objectives: Earlier we demonstrated that immunization with F6, a proinflammatory molecular fraction isolated from the human filarial parasite Brugia malayi, protected the host and eliminated the infection in Mastomys coucha by a Th1/Th2 response including IgG2a antibody response. Whether F6 molecules become accessible to human host during natural course of infection and elicit similar response is not known. The present study was undertaken to determine the profile of IgG subclasses specifically reactive to F6 in different categories of bancroftian filariasis cases to infer any relationship between the levels of a particular F6-specific IgG subclass and the infection or disease status. Methods: Serum samples of normal individuals from filariasis non-endemic regions of India like Jammu & Kashmir, Uttarakhand, and Chandigarh [(NEN-W; n=10), healthy subjects from USA (NEN-U; n=10) and three categories of bancroftian filariasis cases from endemic areas: endemic normals (EN; n=10) with no symptoms and no microfilariae, asymptomatic microfilaremics (ASM; n=10) and chronic symptomatic amicrofilaremics (CL; n=10) were assayed for F6-specific IgG1, IgG2, IgG3 and IgG4 by ELISA using SDS-PAGE-isolated F6 fraction of B. malayi adult worms. Results: Significantly high levels of F6-specific IgG1, IgG2 and IgG3 were found in CL (P<0.001) and EN (P<0.01-0.001) bancroftian filariasis cases compared to NEN-U. Significant levels of F6-specific IgG1 (P<0.01) and IgG2 (P<0.01) but not IgG3 were found in ASM cases compared to NEN-U. The most abundant was IgG2 which when compared to NEN-U, was significantly high in CL (P<0.001) and EN cases (P<0.001), followed by ASM (P<0.01). F6-specific IgG4 response in EN, ASM and CL subjects was not significantly different from the levels of NEN-U. Among the non-endemic normals, the NEN-W subjects showed significant reactivity with IgG2 (P<0.001) but not with IgG1, IgG3 and IgG4 as compared to NEN-U subjects. IgG subclass levels were different in different categories. Interpretation & conclusions: The high levels of F6 reactive IgG1, IgG2 and IgG3 in endemic normals and chronic symptomatic bancroftian patients, and IgG1 and IgG2 in asymptomatic microfilaraemics, suggest that F6 molecules of parasite are accessible in these subjects for IgG subclass-specific immune response and IgG2 may be related to pathogenesis. Studies using individual F6 molecules will be done to identify the molecule(s) involved in infection and protective immunity.

In vitro effect of four herbal plants on the motility of Brugia malayi microfilariae.

BACKGROUND & OBJECTIVE: Disease burden due to lymphatic filariasis is disproportionately high despite mass drug administration with conventional drugs. Usage of herbal drugs in traditional medicine is quite well known but largely empirical. Hence the present study was designed to screen the in vitro antifilarial effect of four herbal plants on Brugia malayi. METHODS: Motility of microfilariae of B. malayi after incubation for 48 h with aqueous/methanol extracts of Vitex negundo L. (roots), Butea monosperma L. (roots and leaves), Ricinus communis L. (leaves), and Aegle marmelos Corr. (leaves) was explored in the concentration range of 20 to 100 ng/ml for possible antifilarial effect by comparing with suitable solvent control. RESULTS: Butea monosperma leaves and roots, Vitex negundo root and Aegle marmelo leaves showed significant inhibition of motility of microfilariae as compared to controls whereas inhibitory activity demonstrated by Ricinus communis L. leaves was not significant. Antifilarial effects imparted by all these extracts were found to be a function of their relative concentrations. Inhibitory concentrations (IC(50)) for the plant extracts with significant antifilarial activity against Brugia malayi microfilariae in in vitro system have been derived to be 82, 83 and 70 ng/ml for Vitex negundo L., Butea monosperma L. and Aegle marmelos Corr. respectively. INTERPRETATION & CONCLUSION: The present study recorded significant antifilarial effect of all plant extracts studied except for Ricinus communis L. leaves and contributes to the development of database for novel drug candidates for human lymphatic filariasis.

Anti-microfilarial activity of methanolic extract of Vitex negundo and Aegle marmelos and their phytochemical analysis.

In the present study, methanolic extracts of roots of Vitex negundo L. and extracts of leaves of Vitex negundo L., Ricinus communis L. and Aegle marmelos Corr. were explored for possible antifilarial effect against Brugia malayi microfilariae. It was observed that among the herbal extracts, root extract of Vitex negundo L. and leaves extract of Aegle marmelos Corr. at 100 ng/ml concentration showed complete loss of motility of microfilariae after 48 hr of incubation. Thin layer chromatography of the extracts revealed the presence of alkaloids, saponin and flavonoids in the roots of Vitex negundo L. and coumarin in the leaves of Aegle marmelos Corr.

Identification of 38kDa Brugia malayi microfilarial protease as a vaccine candidate for lymphatic filariasis.

A FPLC purified 38kDa protease (Bm mf S-7) isolated from B. malayi microfilarial soluble antigen was identified. It showed pronounced reactivity with sera collected from 'putatively immune' asymptomatic and amicrofilaraemic individuals residing in an endemic area for bancroftian filariasis. Further the immune protective activity of Bm mf S-7 antigen was evaluated in susceptible hosts, jirds (Meriones unguiculatus) against B. malayi filarial infection. The antigen showed 89% cytotoxicity against mf and 87-89% against infective (L3) larvae in in vitro antibody dependent cellular cytotoxicity Assay (ADCC) and in situ micropore chamber methods. Bm mf S-7 immunized jirds after challenge infection showed 81.5% reduction in the adult worm burden. The present study has shown that, the 38kDa microfilarial proteases (Bm mf S-7) could stimulate a strong protective immune response against microfilariae and infective larvae in jird model to block the transmission of filariasis. Analysis of IgG subclasses against Bm mf S-7 revealed a significant increase in IgG2 and IgG3 antibodies in endemic normals. Lymphocyte proliferation to Bm mf S-7 was significantly high in endemic normal group as compared to that in clinical and microfilarial carriers. Significantly enhanced levels of IFN-gamma in the culture supernatant of PBMC of endemic normals followed by stimulation with Bm mf S-7 suggest that the cellular response in this group is skewed towards Th 1 type.

Risk factors for acute myocardial infarction in a rural population of central India: a hospital-based case-control study.

BACKGROUND: There is a paucity of data on the relative importance of various traditional risk factors for coronary artery disease among rural Indians. We conducted a prospective case-control study to determine the risk factors for acute myocardial infarction in a rural population of central India. METHODS: We recruited 111 consecutive patients admitted to our hospital with a first episode of acute myocardial infarction and 222 age- and sex-matched controls. Demographics, anthropometric measures, lipids, blood glucose, smoking and other lifestyle factors were compared among cases and controls. Multivariate analyses were used to identify the risk factors independently associated with acute myocardial infarction. RESULTS: Elevated fasting blood glucose (odds ratio [OR] 8.9; 95% confidence interval [CI] 4.5, 17.9), abnormal waist-hip ratio (OR 3.0; 95% CI 1.7, 5.4) and income (OR 4.0 and 5.9 for the high- and middle-income categories, compared to the lowest category) were independently associated with the first episode of acute myocardial infarction. Abnormal triglycerides (OR 1.7; 95% CI 0.9, 3.1) and current smoking (OR 1.9; 95% CI 0.9, 4.0) were risk factors but were not statistically significant. CONCLUSION: Reduction in blood glucose levels and truncal obesity may be important in controlling the burden of coronary artery disease in rural Indians.

Seroreactivity of 31 kDa and 41 kDa mycobacterial secretory proteins isolated from culture filtrate in extra pulmonary tuberculosis.

Despite rapid advances in molecular genetics for detection of mycobacteria, it is clear that interest in serodiagnosis remains high, especially for those situations in which a specimen may not contain the infecting agent in particular in extrapulmonary tuberculosis. Immune response to excretory-secretory (ES) proteins of Mycobacterium tuberculosis (M.tb) has been of diagnostic interest in tuberculosis. In earlier study from our laboratory, a secretory protein M.tb ES-31 has been shown to have diagnostic potential in pulmonary tuberculosis. Further, another M.tb H37Ra ES protein (ES-41) was isolated and purified by trichloroacetic acid solubilization followed by Fast Performance Liquid Chromatography (FPLC). These two protein fractions viz ES-31 and ES-41 secreted by M.tb H37 Ra bacilli were employed in stick indirect penicillinase ELISA to study seroreactivity in extra pulmonary tuberculosis namely tuberculous lymphadenopathy, tuberculous meningitis, abdominal tuberculosis and bone & joint tuberculosis. While using ES-31 antigen 88% (22/25) of tuberculous lymphadenopathy and 90% (9/10) of tuberculous meningitis cases showed positive reaction for tuberculous IgG antibody, ES-41 showed 80% positivity in both groups. In abdominal and bone & joint tuberculosis cases, ES-41 antigen showed better sensitivity of 81.5% (22/27) and 84.6% (22/26) respectively in IgG antibody detection compared to 70% (19/27) and 69.2% (18/26) shown by ES-31. This study is of interest that different antigen protein fractions of M.tb exhibit differential seroreactivity, as ES-31 protein showed good potential in detecting tuberculous IgG antibodies in tuberculous lymphadenopathy (TBLN) & tuberculous meningitis (TBM), while ES-41 in abdominal and bone & joint tuberculosis cases.

Analysis of IgG subclasses and IgE antibodies across the clinical spectrum of bancroftian filariasis in an endemic area.

Analysis of immune response in individuals with different clinical manifestations living in filaria endemic area will be of interest to understand the immunological events associated with the disease development in filaria infected endemic population. The levels of four IgG subclasses and IgE antibodies against Brugia malayi microfilarial excretory-secretory (Bm mf ES) antigen as well as circulating filarial antigen level were evaluated in 84 individuals belonging to different groups in an endemic area for bancroftian filariasis. Microfilaraemics showed significantly elevated levels of IgG4 and IgG3 antibodies compared to endemic normals (P < 0.02). As many as 70% of this group were positive for IgG4 & IgG3 antibodies. While Acute filarial cases had pronounced IgG1 antibodies(P < 0.001), the Grade I chronic cases showed higher levels of IgG3 and IgG4 antibodies (P < 0.02), Occult filarial cases had higher levels of IgG4 and IgG3 (P < 0.02) and also of IgG4 antibodies (P < 0.001). IgE antibodies were found to be elevated in microfilaraemics as well as other clinical filarial groups. Circulating filarial antigen was detected in 95% of microfilaraemics, 60% of acute cases, 75% to 90% of different grades of chronic filarial cases, 100% of occult cases and none of the endemic normals.

Pharmacotherapy for secondary prevention of stroke.

Stroke is a leading cause of mortality worldwide. It has well modifiable risk factors, which makes prevention an effective strategy. Antithrombotics and anticoagulants have been the main pharmacological options in secondary prevention. A number of new antiplatelet drugs have been introduced over the past decade. The more recent concepts in the understanding of stroke and atherosclerosis have paved the way for a number of newer pharmacological interventions like angiotensin enzyme inhibitors, statins and vitamins. The pharmacological armamentarium to treat stroke is expanding.

Immunodiagnosis of pulmonary tuberculosis by concomitant detection of antigen and antibodies of excretory-secretory protein of Mycobacterium tuberculosis H37Ra.

With a view to diagnosing tuberculosis in populations in endemic areas, excretory-secretory antigen fraction (Mtb EST -6) of purified Mycobacterium tuberculosis H37Ra and affinity purified polyclonal antibodies against Mtb EST were used to detect both antibodies and circulating antigen in the sera of patients and disease-free individuals. Indirect stick penicillinase ELISA system using Mtb EST-6 detected antigen-specific IgG antibody in 84% of sputum positive, 77% of sputum negative pulmonary tuberculosis patients and 7% of healthy and 11% of subjects with nontub~rculosis diseases. Similarly, a sandwich penicillinase ELISA system using affinity purified anti Mtb EST antibodies detected circulating antigen in 83% and 61 % of sputum positive and negative pulmonary tuberculosis subjects. In contrast only 24% of healthy and 18% of disease controls showed seropositivity. Antibody assay showed higher sensitivity and specificity (83% and 91 % respectively) compared to antigen detection (sensitivity of 79% and specificity of 79%). However, by concomitant use of both assays it was possible to enhance the specificity of detection to 98%, though sensitivity was reduced marginally to 70%. The present study confirms the presence of both antigen and specific antibodies in the circulation during clinical disease and draws attention to the utility of Mtb EST -6 as a diagnostic marker of pulmonary tuberculosis

Immunoprophylactic studies with a 43 kDa human circulating filarial antigen and a cross reactive 120 kDa Brugia malayi sodium dodecyl sulphate soluble antigen in filariasis.

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.

Detection of filarial antigen by inhibition enzyme linked immunosorbent assay using fractionated Brugia malayi microfilarial excretory secretory antigen.

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.

Diagnostic utility of fractionated urinary filarial antigen.

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.

Immunoprophylaxis against filarial parasite, Brugia malayi: potential of excretory-secretory antigens in inducing immunity.

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.

Differential reactivity of filarial antigens with human sera from bancroftian filariasis endemic zone.

The reacting pattern of circulating filarial antigen fraction-2 from Wuchereria bancrofti and soluble antigen from adult Brugia malayi with bancroftian filarial sera were analysed by immunoblotting technique and enzyme linked immunosorbent assay. Microfilaraemic sera reacted specifically with proteins of molecular weight 200, 120, 97, 56, 54, 43, 26 and 17 kDa of circulating Filarial antigen fraction-2 and 44, 40, 38, 31, 22 and 18 kDa of Brugia malayi adult soluble antigen. Clinical filarial sera identified protein molecules of 56, 54 and 42 kDa of circulating filarial antigen fraction-2 and 19, 16 and 14 kDa of Brugia malayi adult soluble antigen. Some components of both the antigen preparation were also identified by endemic normal sera i.e .proteins 120, 97, 62, 43 and 33 kDa of circulating filarial antigen fraction-2 and 170, 120, 43, 31 and 12 kDa of Brugia malayi adult soluble antigen. One of the sodium dodecyl sulphate-polyacrylamide gel electropherosis fractions of circulating filarial antigen fraction-2 (CFA2-8) and Brugia malayi adult soluble antigen fraction-6 when used in enzyme linked immunosorbent assay could differentiate microfilaraemic sera from endemic normal and clinical filarial sera. The other antigen fractions (CFA2-2, 6 and 7 and BmA-2) showed a high geometric mean titre of filarial immunoglobulin G antibodies in endemic normal sera when compared to microfilaraemia and clinical filarial sera. These proteins need to be further studied to assess their involvement in protecting from filarial infection in an endemic area.

Analysis, characterization and diagnostic use of circulating filarial antigen in bancroftian filariasis.

Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of circulating filarial antigen fraction-2 isolated from plasma of microfilaraemic patients with Wuchereria bancrofti infection has shown 21 bands with molecular weights ranging from 12 to 120 kDa. The gel (12 cm) was sliced at an interval of one cm and the eluates of all the gel slices viz., CFA2–1 to CFA2–12 showed the presence of filarial antigen by sandwich enzyme-linked immunosorbent assay. The low molecular weight circulating filarial antigen fractions were found to share a common epitope with Wuchereria bancrofti microfilariae excretory-secretory antigen and urinary filarial antigen. The 3 antigen fractions CFA2-1, CFA2–9 and CFA2–12 showed higher sensitivity in detecting filarial immunoglobulin Μ antibodies than immunoglobulin G antibodies. However CFA2–9 fraction was found useful in serological differentiation of microfilaraemics from those with disease manifestations when filarial immunoglobulin G antibodies were detected. The antigenic epitope of CFA2–1 appears to be a carbohydrate, whereas CFA2–9 appears to be protein in nature.

Diagnostic utility of monoclonal antibodies raised against microfilarial excretory-secretory antigens in bancroftian filariasis.

Two monoclonal antibodies Wuchereria bancrofti Ε 33 and Wuchereria bancrofli Ε 34 raised against Wuchereria bancrofti microfilarial excretory-secretory antigens were studied for their diagnostic utility. Wuchereria bancrofti Ε 34 monoclonal antibody was found to be relatively specific and sensitive in detection of circulating filarial antigen. When Wuchereria bancrofti Ε 34 monoclonal antibody was used alongwith immunoglobulin G fraction of human filarial serum immunoglobulins in double antibody sandwich enzyme linked immunosorbent assay. 68% of microfilaraemic sera (26 out of 38). 12% of clinical filarial sera (3 out of 25), 13% endemic normal sera (2 out of 15) and none of the 20 non-endemic normal sera showed the presence of filarial antigen. The filarial antigen detected by Wuchereria bancrofti Ε 34 monoclonal antibody in double antibody sandwich enzyme linked immunosorbent assay is possibly associated with the active stage (microfilaraemia) of infection.

Monoclonal antibodies against Wuchereria bancrofti microfilarial excretory-secretory antigens.

A battery of monoclonal antibodies were produced against Wuchereria bancrofti microfilarial excretory-secretory antigens and their specificity was studied using different filarial antigens. Among the 1116 wells plated out, 42 % of the wells developed hybrids and 5 % of the hybrids showed anti Wuchereria bancrofti microfilarial excretory-secretory antigens. Specificity studies on the antibodies produced from 63 cloned and expanded hybrids showed 10 clones which were specifically positive only to Wuchereria bancrofti microfilarial excretory-secretory antigens.

Evaluation of fractionated Wuchereria bancrofti microfilarial excretory-secretory antigens for diagnosis of bancroftian filariasis by enzyme linked immunosorbent assay.

The Wuchereria bancrofti microfilarial excretory-secretory antigens were fractionated into ES1, ES2, ES3 and ES4 by ultra-membrane filtration and evaluated for their diagnostic utility by enzyme linked immunosorbent assay. Three of the four fractions showed antigenic activity (ES2, ES3 and ES4). The antigen fractions ES2 and ES4 were highly active in the detection of filarial IgM antibody in clinical filariasis and microfilaraemia respectively. The chemical characterization of the ES2 and ES4 antigen fractions showed that they were glycoproteins.

Detection of filarial infection using Wuchereria bancrofti microfilariae culture antigen and filter paper blood samples in enzyme linked immunosorbent assay.

Blood collected on filter paper by finger-prick gave results comparable to intravenous serum samples when analysed by enzyme-linked immunosorbent assay (ELISA). All the 100 microfilaraemia, 5 out of 100 endemic normals and none of the 10 nonendemic normal filter paper blood samples showed the presence of filarial antibody when tested by this method,using culture antigen and anti-immunoglubulins, class G, Μ and A — penicillinase conjugate. When the same samples were screened for the presence of IgM antibody, 91 out of 100 microfilaraemia, 13 out of 100 endemic normal and none of the 10 nonendemic normal samples showed a positive reaction. Enzyme linked immunosorbent assay, using culture antigen and filter paper blood samples, appears to work in large field studies for detection of filarial infection.