Cabrera Z et al. (1989) Trop Med Parasitol "Specific detection of human antibodies to Onchocerca volvulus."

Cabrera Z, Yarzabal L, Forsyth K, Pabon R, Gomez Priego A, Parkhouse RM

[Trop Med Parasitol, 1989]

Specific diagnosis of antibodies to Onchocerca was achieved through (1) the construction of direct and indirect ELISA systems, and (2) restricting ELISA assays to the IgG4 class. The direct ELISA was based on the isolation of a surface derived, low molecular weight surface antigen preparation containing two main antigens (M. wt. 16.2 and 12.8 kDA) as defined by Western blot analysis. The direct ELISA system detected antibodies in children of six years old, and may therefore be applicable to detecting reinvasion in OCP areas of Onchocerca volvulus control. The indirect ELISA system was a competitive binding ELISA-based assay using a monoclonal antibody recognising two Onchocerca components (M. wts. 15.6 and 25.9) on a Western blot. The direct and indirect ELISA systems were similarly specific and sensitive when evaluated in a preliminary survey. The direct ELISA system yielded a specificity and sensitivity of: 100% and 100% respectively, using Mexican endemic and Mexican intestinal nematode infection sera as positive and negative controls respectively: 91% and 96% respectively, using Venezuelan endemic and Venezuelan Mansonella ozzardi infection sera as positive and negative controls, respectively: 87% and 93% respectively, using African endemic and Papuan (New Guinea) Wuchereria bancrofti infection sera as positive and negative controls respectively: 93% and 93% respectively, using African endemic and Indian W. bancrofti infection sera as positive and negative controls respectively. Similar specificity and sensitivity levels were obtained when the same comparisons were made using the indirect (inhibition) ELISA assay. These values may be contrasted with the currently used PBS extract of O. volvulus which yielded specificities of less than 10% in all the above comparisons.(ABSTRACT TRUNCATED AT 250 WORDS)

Bartlett A et al. (1975) Tropenmed Parasitol "Preliminary studies on the application of enzyme immunoassay in the detection of antibodies in onchocerciasis."

Bidwell DE, Bartlett A, Voller A

[Tropenmed Parasitol, 1975]

Preliminary enzyme-linked immunosorbent assay (ELISA) with serum from a patient with onchoceriasis revealed extensive cross-reactions with various nematode antigens. Further tests on a batch of sera from people with proven O. volvulus infections using O. gutturosa antigen, showed that almost all the sera gave higher ELISA values than did control African sera.

Wahyuni S et al. Parasite Immunol "Comparison of an enzyme linked immunosorbent assay (ELISA) and a radioallergosorbent test (RAST) for detection of IgE antibodies to Brugia malayi."

Mangali A, Supali T, Van Ree R, Yazdanbakhsh M, Sartono E, Wahyuni S

[Parasite Immunol]

The enzyme linked immunosorbent assay (ELISA) for specific IgE antibodies to Brugia malayi was compared with the radioallergosorbent test (RAST) for use in immunoepidemiological studies of lymphatic filariasis. Sera used were from individuals (aged 5-82 years) living in an area endemic for lymphatic filariasis in South Sulawesi, Indonesia. The percentage of positive IgE ELISA reactions (52.6%) among the population was lower than the percentage of positive RAST (94.5%). Although an overall significant concordance was found between the two assays (P < 0.001), 328 (42.7%) individuals with a positive RAST result were negative in the ELISA, whereas only 6 (0.8%) subjects were positive by ELISA, yet negative by RAST. When the population was divided into those with active infection (positive for anti-filarial IgG4) and those not infected (mf-negative and negative for anti-filarial IgG4), the correlation between the two tests was higher in the IgG4-positive (rho = 0.70) than in the IgG4-negative (rho = 0.52) group. These results indicate that in assessment of B. malayi specific IgE antibody, RAST is superior to ELISA. However, given the use of radioactivity in the RAST method and given our results obtained in subjects with high anti-filarial IgG4, one could consider using the IgE-ELISA in areas with high endemicity for filariasis. In areas with low endemicity or where control programs are implemented, sera will have to be tested by RAST.

Weiss N et al. (1981) Acta Trop "IgE antibodies in human onchocerciasis. Application of a newly developed radioallergosorbent test (RAST)."

Weiss N, Speiser F, Hussain R

[Acta Trop, 1981]

A radioallergosorbent test (RAST) was developed to detect IgE antibodies against adult Onchocerca volvulus antigens coupled to CnBr-activated Sepharose. Twenty-four out of 25 (96%) onchocerciasis sera were reactive. The lower limit of sensitivity was estimated to be at approx. 3 ng/ml IgE antibodies. Tests of sera from patients with non-filarial helminth infections showed much less cross-reactivity with RAST than with an enzyme-linked immunosorbent assay (ELISA) detecting IgG and IgM antibodies against the same antigen preparation. At a specificity comparable to that of RAST, the sensitivity of ELISA was only 61%. A heterologous antigen, prepared from female Dipetalonema viteae worms, was comparatively evaluated with O. volvulus. In RAST and ELISA, onchocerciasis sera were less reactive than against the O. volvulus antigen. Since sera from patients with non-filarial helminth infections were more reactive in RAST and almost equally reactive in ELISA using the D. viteae antigen, sensitivity was 83% for RAST and only 22% for ELISA (compared at the specificity identical to that of the O. volvulus RAST).

Ambroise-Thomas P et al. Bull Soc Pathol Exot Filiales "[Serodiagnosis of onchocerciasis using micro-ELISA. Study of 450 sera and comparison with indirect immunofluorescence]."

Ambroise-Thomas P, Desgeorges PT, Daveau C

[Bull Soc Pathol Exot Filiales]

The microtest ELISA has been used for human Onchocerciasis serological study. The antigens employed were adult Onchocerca volvulus extracts, collected from dissected nodules, delipidized and cleared from human proteins by affinity Chromatography. Under the circumstances, the positivity limit of the test seems excellent (maximum )D: 0,23) defined with 171 negative sera, 66 of them taken from Africans. Specificity controls were studied with 56 heterologous sera; cross-reactions occurred with hydatidosis and especially wit various nematode infections, in particular loasis. With reagents and technical conditions used, the specificity limit of the test corresponds to an OD of 0,4 (measured with a 3 mm optical course). The diagnosis value of the test was verified by studying sera from 90 individuals wit a positive skin biopsy and with sera from 233 adults living in endemic areas. For all the infected people, the global percentage of positivity with ELISA is not greater than that with indirect immunofluorescent antibody test (85%). On the other hand, the micro-test ELISA seems slightly more sensitive in detection of high serological positivities. We did not find any statistically relationship presence and quantity of microfilarial worms in skin biopsy and positivity with the microtest ELISA. Likewise, in some polyinfested patients (with Onchocerca volvulus and Dipetalonema perstans or Wuchereria bancrofti), we did not observe any correlation between the results given the microtest ELISA and the quantity of microfilariae in the blood stream.

Hamilton RG et al. (1981) J Immunol Methods "The quantitation of parasite-specific human IgG and IgE in sera: evaluation of solid-phase RIA and ELISA methodology."

Hussain R, Ottesen EA, Hamilton RG, Adkinson NF

[J Immunol Methods, 1981]

We have developed a non-competitive solid-phase radioimmunoassay (SPRIA) to quantitate both human IgE and IgG antibodies against soluble adult antigens of Brugia malayi (B.m.), a filarial parasite causing extensive infection throughout the tropics. Previously enzyme-linked immunosorbent assays (ELISA) had been used to detect microgram/ml levels of IgG anti-B.m., but IgE antibodies were difficult to detect in this system. Since the SPRIA successfully quantitates both IgG and IgE anti-B.m., we sought to examine the reasons for the SPRIA's apparent superiority in detecting IgE anti-B.m. by extracting specific IgG from sera with high levels of IgE and IgG anti-B.m. antibodies. IgE anti-B.m. was then quantitated in these sera using both the SPRIA and ELISA methods. Results indicate that IgG anti-B.m. does not interfere with detection of specific IgE antibody in the SPRIA but does interfere in the ELISA. While ELISA permits detection of IgE anti-B.m. in the absence of competing IgG anti-B.m., as levels of specific IgG increase, the IgE is no longer detectable. These differences between SPRIA and ELISA can be explained by the SPRIA's antigen excess conditions which assure that there are sufficient antigens both to detect all anti-B.m. antibodies present in the serum and to adequately represent all antigen specificities in the crude B.m. extract. Our findings commend the use of SPRIA methods over ELISA in assessment of B.m.-specific IgE antibody in filariasis and indicate a potential role for SPRIA methods in absolute quantitation of specific serum antibodies.

Schlie-Guzman MA et al. (1989) Trop Med Parasitol "Antigen detection in onchocerciasis: correlation with worm burden."

Schlie-Guzman MA, Rivas-Alcala AR

[Trop Med Parasitol, 1989]

Detection of O. volvulus antigen by indirect ELISA test in the serum and the urine of 169 individuals with residence in the southeast onchocerciasis endemic focus in Chiapas, Mexico was performed. Every individual under study was physically examined for signs of onchocerciasis in particular for subcutaneous nodules, dermic lesions, ocular damage and history of Mazzotti reaction. Of the total cases, 91.7% were positive for skin microfilariae. Only 32.2% of the microfilariae positive cases carried at least one palpable nodule. The sensitivity of the ELISA test was 92.3% for serum and 85.9% for urine. A good correlation between the transformed numbers of skin microfilariae (square root of x + 1) and the positivity of the ELISA test for serum and for urine was found. It was also observed that the ELISA test values for the sera and for the urine showed a good correlation with r = 0.76 and Z0.95 less than 0.005. This serological test can be used for seroepidemiological surveys and for orientating the activity of massive onchocerciasis treatment campaigns.

Lavebratt C et al. (1997) Scand J Infect Dis "Evaluation of serological assays for diagnosis of onchocercosis."

Eriksson T, Thors C, Lavebratt C, Guzman G, Ljungstrom I, Akuffo HO

[Scand J Infect Dis, 1997]

Microscopic analysis of skin snips is the most widely used diagnostic technique for onchocercosis in endemic countries. The invasive nature and low sensitivity of that procedure has called for alternative diagnostic methods for this disease. Presently, serological assays detecting filariosis in general are available for routine analysis. However, serological assays specific for onchocercosis are still not universally available. We have evaluated the performance of a dot blot assay (DBA) as a potential method for specific detection of onchocercosis. The DBA, which detects IgG, as compared with 2 IgG4-immunoblot assays, all employing Onchocerca volvulus antigen. Furthermore, an enzyme-linked immunosorbent assay (ELISA) and an immunofluorescence assay (IFA) based on antigens from Acanthocheilonema viteae and Brugia malayi, respectively, were included in the comparison. Samples from microfilariae-positive patients and negative controls from the onchocercosis-endemic country Ghana were analysed. The DBA was significantly more sensitive and specific than the IgG4-assays and the ELISA, respectively. Furthermore, the anti-filarial Ig was increased in patients 1 month post-ivermectin treatment. Sera from patients with suspected filariosis from different parts of the world were analysed using DBA, ELISA and IFA. Patients responding positively in the DBA (12%) had clinical symptoms compatible with onchocercosis whereas those positive in ELISA and IFA (53% and 48%, respectively) had various clinical symptoms. These results indicate that the DBA is more specific than and as sensitive as the ELISA and the IFA presently used for the diagnosis of onchocercosis.

Egwang TG et al. (1994) Clin Exp Immunol "Evaluation of Onchocerca volvulus-specific IgG4 subclass serology as an index of onchocerciasis transmission potential of three Gabonese villages."

Everaere S, Kombila M, Richard-Lenoble D, Ngari P, Nguiri C, Egwang TG, Duong TH, Gbakima AA

[Clin Exp Immunol, 1994]

The major objective of this study was to evaluate the usefulness of IgG4 ELISA and Western blot analysis, using a crude extract of Onchocerca volvulus adult worms as antigens, for diagnosing onchocerciasis in a Gabonese paediatric population with mixed filarial infections. The subjects had loaisis, streptocercosis or mansonellosis in addition to onchocerciasis. Control sera from loaisis or mansonellosis subjects residing outside the endemic zone were used to provide the cut-off point for positive results. The IgG4 ELISA had a specificity of 96% but a lower sensitivity of 78.7%. It detected 25 onchocerciasis cases out of 65 individuals who were negative on parasitological examination. Furthermore, the ELISA provided a more accurate picture of onchocerciasis transmission in a village with very low skin microfilarial load. A 27.5-kD antigen was identified on Western blots as a marker of onchocerciasis. The paediatric population provided a reliable window for assessing the parasitologic and serologic parameters in the three villages with disparate levels of onchocerciasis transmission.

Cabrera Z et al. (1987) Parasite Immunol "Isolation of an antigenic fraction for diagnosis of onchocerciasis."

Cabrera Z, Parkhouse RM

[Parasite Immunol, 1987]

A surface enriched fraction was prepared from adults of Onchocerca volvulus by brief extraction of entire worms with detergent. This was then gel filtered to yield a low molecular weight fraction which functioned specifically in ELISA analysis. An identical result was also obtained when the related cattle parasite, O. gibsoni, was similarly fractionated and tested. The low molecular weight fraction contained at least four antigenic components when examined by coprecipitation and immunoblotting studies. One ml of packed worms yielded sufficient low molecular weight antigen to examine about 2,000 human sera by the ELISA procedure, and the test was sensitive at human serum dilutions down to 1/400. A preliminary study with individual sera from Onchocerciasis endemic and non-endemic areas of Southern Mexico yielded 0/24 false positives, 3/24 false negatives and a significant ELISA value in 21/24 sera from proven cases of Onchocerciasis.