Distribution of immunoglobulin classes and IgG subclasses against a culture filtrate antigen of Burkholderia pseudomallei in melioidosis patients.

The class and subclass distribution of antibody response to the culture filtrate antigen (CFA) of Burkholderia pseudomallei was examined in the sera of 45 septicaemic and 17 localised melioidosis cases and 40 cases clinically suspected of melioidosis and the results were compared with those from high-risk and healthy control groups. The geometric mean titre index (GMTI) values for all classes and subclasses of immunoglobulins examined were higher for sera from the proven and clinically suspected melioidosis cases than for the control groups. However, the highest response in the three patient groups was that of IgG with GMTIs ranging from 219.4 to 291.6 and the lowest was for IgM with GMTIs of 22.5, 24.3 and 28.7. The IgA response was intermediate with GMTIs ranging from 119.2 to 170. The GMTIs were highest for IgG in septicaemic and localised infections and for IgA and IgM in localised infections. As regards IgG subclass distribution, IgG1 and IgG2 were the predominant subclasses produced against the CFA in contrast to IgG3 and IgG4, which were produced in low amounts. None of the sera from the control groups had any significant titres of antibodies.

Detection of immunoglobulins M and G using culture filtrate antigen of Burkholderia pseudomallei.

IgM and IgG based ELISA systems were developed using the culture filtrate antigen (CFA) of Burkholderia pseudomallei. The assays were evaluated using 95 sera from 66 septicemic cases and 47 sera from 20 cases with localized melioidosis. In addition 65 sera from culture negative cases that were also serologically negative for other endemic infections clinically suspected of melioidosis were included. These were compared with sera from 260 non-melioidosis cases, 169 sera from individuals with high risk of acquiring the infection and 48 sera from healthy controls. The IgG-ELISA was 96% sensitive and 94% specific. All sera from cases with septicemic and localized infections and 61 of 63 sera from clinically suspected melioidosis cases were positive for IgG antibody. The geometric mean titre index (GMTI) values of IgG antibody in melioidosis cases were significantly higher (p < 0.0005) compared to that of healthy subjects, high risk group and subjects with non-melioidosis infections. The sensitivity and specificity of IgM ELISA was 74 and 99% respectively. The GMTI value of IgM antibody in the sera of melioidosis cases was significantly higher as compared to that of non-melioidosis disease controls (p < or = 0.001). These results demonstrate that the detection of IgG is a better indicator of the disease in the diagnosis of melioidosis.

Evaluation of a new commercially available immunoglobulin M and immunoglobulin G immunochromatographic test for diagnosis of melioidosis infection.

An immunochromatographic test for the rapid determination of immunoglobulin M (IgM) and IgG antibodies to Burkholderia pseudomallei was evaluated by using sera from bacteriologically confirmed melioidosis patients and high-risk and clinically suspected patients, along with disease control groups. The sensitivities were 100 and 93% for the IgG and IgM tests, respectively, while the specificity was 95% for both assays. The test was rapid and simple to perform, with results obtained in 10 min.

Diagnostic potential of fractionated Brugia malayi microfilarial excretory/secretory antigen for bancroftian filariasis.

Due to the non-availability of sufficient parasite material from Wuchereria bancrofti, a heterologous filarial antigen from Brugia malayi has been investigated for the diagnosis of bancroftian filariasis. B. malayi microfilarial excretory/secretory antigen (BmmfES) effectively inhibited the binding of circulating filarial antigen fractions (CFA2-1, 9, 11 and 12) from microfilaraemic cases, and of W. bancrofti microfilarial excretory/secretory antigen, to the immunoglobulin G (IgG) fraction of anti-filarial serum immunoglobulins. BmmfES was separated by ion-exchange chromatography on DEAE cellulose into 2 fractions, BmE DE1 and BmE DE2. BmE DE1 was marginally superior to whole BmmfES and BmE DE2 in detecting filarial IgG antibodies in human sera. 230 human sera from different groups of patients were screened against BmE DE1, which detected specific IgG in 83% of sera from microfilaraemic donors, 83% of sera from patients with clinical filariasis, 17% of sera from normal residents of an endemic area, and in none of the sera from persons living in a non-endemic area. The assay system using BmE DE1, with a sensitivity of 83% and specificity of 83%, should be very useful in detecting microfilaraemia, particularly in active clinical infections where the parasite is usually not seen.

Analysis and diagnostic use of Brugia malayi adult antigen in bancroftian filariasis.

Detergent-soluble antigens of Brugia malayi adult worms (BmA SDS S Ag) were analysed for their antigenic activity and potential use in diagnosis of bancroftian filariasis. Analysis of SDS-PAGE fractions of BmA SDS S Ag against antifilarial antibodies, that is, human filarial serum immunoglobulin G and anti BmA SDS S Ag antibody, revealed two active antigen fractions: BmA-6 and BmA-9. Antibodies raised to BmA-6 and BmA-9 were tested with antigens isolated from infected human body fluids such as circulating filarial antigen (CFA2), urinary filarial antigen (UFAC2) and hydrocele fluid antigen (HFA). Both antibodies showed high reactivity with CFA2-1, 6 and 9 as well as UFAC2-5, 6 and 9 antigenic fractions. In immunoblotting studies, anti BmA-6 antibody detected specific antigens of high microfilaraemic reactivity such as 120, 54, 26 and 22 kDa. In inhibition ELISA using anti BmA SDS S Ag antibody and antigen fraction BmA-6, filarial antigen was detected in 85% of microfilaraemic, 35% of clinical filarial and 20% of endemic normal sera samples. When anti BmA SDS S Ag antibody and BmA-9 were used, 80% of microfilaraemic, 35% of clinical filarial and 25% of endemic normal sera showed positive reaction for filarial antigen. The analysis of urine samples showed the presence of filarial antigen in 76 and 72% of microfilaraemic cases using BmA-6 and BmA-9 fractions respectively while only 20% of endemic normals were positive using both the antigen fractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunoprophylactic potential of a 120 kDa Brugia malayi adult antigen fraction, BmA-2, in lymphatic filariasis.

A 120 kDa antigen containing SDS-PAGE fraction BmA-2 isolated from Brugia malayi adult parasite was highly reactive with normal sera from filarial endemic area. BmA-2 was analysed for its prophylactic potential in in vitro and in vivo. Sera collected from BmA-2 immunized jirds induced a significant level (80 to 90%) of protection against infective larvae and microfilariae in in vitro ADCC assay as well as in in situ micropore chamber implantation studies. Mastomys natalensis immunized with BmA-2 showed a significant level of protective response against circulating microfilariae by clearing 90% of them from circulation by fifth day after challenge infection. Immunization of jirds with BmA-2 resulted in an enhanced level of antibody response against BmA-2 and 88% reduction in the development of the parasites to the adult stage. Passive transfer of immunesera from jirds immunized with BmA-2 to naive jirds resulted in 71% reduction in adult worm recovery as observed 90 days after challenge infection with B. malayi. On the other hand the passive transfer of non-adherent spleen cells from immune jirds did not show any significant effect on the development of parasite. Administration of jirds anti BmA-2 serum to microfilaraemic jirds showed a temporary decrease in microfilarial count which was increased to pretherapeutic level within 100 days and there was no effect on the adult worms. This implies that the immune protective effect of BmA-2 is mainly antibody dependent and active immunization with BmA-2 is effective against filarial infection.

Detection of tuberculous IgG antibodies using Mycobacterium tuberculosis H37Ra, excretory secretory antigen and tuberculin-purified protein derivative.

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.