ELISA--a possible alternative to establish a therapeutic drug monitoring system in severe and complicated falciparum malaria.

A modification of an enzyme-linked immunosorbent assay (ELISA) for the quantitative determination of plasma quinine levels is described. The test is rapid, sensitive and reproducible.

Serological response of mice to Fusobacterium necrophorum.

Mice immunised with killed or living Fusobacterium necrophorum, by five different regimens, almost invariably failed to produce antibodies demonstrable by a passive haemagglutination test. An enzyme-linked immunosorbent assay (ELISA), however, usually demonstrated a serum antibody response. This suggested that F necrophorum was not in fact immunosuppressive in mice--a possibility that had been entertained to explain the great difficulty in protecting mice immunologically against challenge with F necrophorum.

Malaria chemoprophylaxis with chloroquine in young Nigerian children. II. Effect on the immune response to vaccination.

The immune response of 198 young Nigerian children protected against malaria by chemoprophylaxis with chloroquine to immunization with triple, poliomyelitis, measles, typhoid, meningococcal and BCG vaccines was compared with the immune response to vaccination of 185 control children. Good responses to triple, measles and BCG vaccines were shown by children in both groups; poorer responses were obtained to poliomyelitis, typhoid and meningococcal vaccines. The response to immunization of protected children was similar to that observed among control children for all the vaccines tested except for meningococcal polysaccharide vaccine. Protected children showed a significantly greater antibody response to both group A and group C meningococcal polysaccharides than control children. This finding supports the results of previous studies which have shown that the immune response to meningococcal polysaccharide vaccines is adversely affected both by acute malaria and by asymptomatic malaria parasitaemia.

Malaria chemoprophylaxis with chloroquine in young Nigerian children. I. Its effect on mortality, morbidity and the prevalence of malaria.

One hundred and ninety-eight Nigerian children who received weekly chemoprophylaxis with chloroquine from shortly after birth until the age of one year or two years and 185 age-matched controls were studied. Chemoprophylaxis with chloroquine was partially, but not completely, effective in controlling malaria. Clinical malaria was documented significantly less frequently in protected children than in control children, and only 9% of random blood films obtained from protected children were positive for Plasmodium falciparum while 41% of random blood films from control children were positive for this parasite. Mean malaria antibody levels were lower in protected than in control children; for ELISA and precipitin antibodies the difference between the two groups was less marked at two years than at one year. Mortality was similar among protected and among control children. No rebound mortality or morbidity was observed after chemoprophylaxis was stopped.

Demonstration of cross-reactive antigens in F38 and related mycoplasmas by enzyme-linked immunosorbent assay (ELISA) and immunoblotting.

The ELISA and an immunoblotting technique were used to study F38-type mycoplasmas - an important cause of contagious caprine pleuropneumonia - and a number of related mycoplasma species, subspecies, types or serogroups. Two-way ELISA cross-reactivity was demonstrated between five mycoplasmas, namely strain F38, Mycoplasma mycoides subsp. mycoides (LC strain), M. equigenitalium, M. primatum and bovine serogroup 7. In addition one-way cross-reactivity was demonstrated between F38 and each of the following mycoplasmas: M. mycoides subsp. mycoides (two SC strains), M. mycoides subsp. capri, and bovine serogroup L. F38 and M. capricolum did not cross-react. Immunoblot analysis, unlike ELISA, revealed that F38 and M. capricolum were closely related. At least four major protein antigens were shared between F38, M. mycoides subsp. mycoides (SC and LC strains), M. mycoides subsp. capri and bovine serogroup 7. The ELISA cross-reactions (above) shown by M. equigenitalium and M. primatum with each other, with F38 and with other mycoplasmas were not apparent by immunoblotting.

A comparison of chloroquine and pyrimethamine as malaria chemoprophylactics in young Nigerian children.

The efficacy of chloroquine and pyrimethamine as malaria chemoprophylactics was investigated in young Nigerian children. Chloroquine resistance had not been documented in the study area; pyrimethamine resistance was probably present but uncommon. Children who received weekly chemoprophylaxis with pyrimethamine had a lower prevalence of malaria parasitaemia and malaria antibodies than children who received weekly chemoprophylaxis with chloroquine. Pyrimethamine given monthly gave a comparable degree of protection to chloroquine given weekly. Chloroquine frequently induced vomiting in young children and this may have impaired its efficacy as a prophylactic. We conclude that, in an area where neither chloroquine nor pyrimethamine resistance is prevalent, pyrimethamine is a better chemoprophylactic for young children than chloroquine.

The measurement of human erythrocyte carbonic anhydrase I by the enzyme linked immunosorbent assay (ELISA).

A method is described for the assay of human erythrocyte (RBC) carbonic anhydrase I (HCAI) by the enzyme linked immunosorbent assay. The method was found to be a simple, reliable and precise technique and gave a mean C.V. for 40 samples, assayed in quadruplicate, of 3.32% and a range of 0.84-5.9. The mean erythrocyte HCAI value and standard deviation for 20 normal men and women were respectively 16.9 +/- 3.4 and 15.4 +/- 2.1 mg HCAI/g haemoglobin. The use of heparin as an anticoagulant interfered with the assay resulting in apparent HCAI concentrations as low as 60% of those obtained using EDTA.

Malaria diagnosis by enzyme-linked immunosorbent assays.

Enzyme-linked immunosorbent assays (ELISA) for detecting malarial parasites in blood were tested on uninfected monkeys and in monkeys infected with Plasmodium falciparum. A double antibody sandwich ELISA detected one malarial cell per 10(3) uninfected cells, and an inhibition ELISA detected on infected cell per 10(4) uninfected erythrocytes. These methods are not yet as sensitive as conventional blood-film examinations, in which a well-trained microscopist might be expected to detect one malarial cell per 10(6) erythrocytes. Nevertheless, ELISA offers an objective means of detecting malaria and is particularly advantageous since up to 100 samples may be processed simultaneously.

A comparison of three tests for rubella antibody screening.

Sera from 1000 women attending antenatal clinics were screened for the presence of rubella antibody by haemagglutination inhibition (HI), single radial haemolysis (SRH), and enzyme-linked immunosorbent assay (ELISA). With 925 sera concordant results were obtained with all three tests. There were 46 false-negative HI tests due to the necessity of allowing for residual non-specific inhibitors. With SRH there was one false positive and three that were negative by SRH but HI- and ELISA-positive. By ELISA 14 sera gave a false-positive result (OD 405 nm greater than or equal to 0.2). Ten of these could be eliminated by taking an OD 405 nm of 0.5 as the threshold but then another 10 sera became false negatives.

Comparisons of serological tests for Babesia in British cattle.

A comparison was made between the microplate enzyme linked immunosorbent assay (ELISA) and the indirect fluorescent antibody (IFA) and complement fixation (CF) tests for the detection of antibodies in the serum of cattle experimentally infected with Babesia divergens and B major. Antibodies were detected using all three tests but they were detected earlier using the CF test. However CF titres were consistently lower than those obtained using the other tests. Although there was little to choose between the IFA and ELISA tests, it was suggested that the ELISA may be preferable since it is less subject to operator error and operator stress, and can be adapted readily to field use.

Enzyme immunoassays with special reference to ELISA techniques.

In this review outlines are given on various types of enzyme immunoassay. The applications to such enzyme immunoassays, especially ELISA, are dealth with in detail. It is concluded that these techniques have high sensitivity and will be suitable in due course as routine laboratory tests.

IgM and antibody measurement in the diagnosis and management of Gambian trypanosomiasis.

Serum and cerebrospinal fluid (CSF) IgM were measured in 182 patients at various stages of Gambian sleeping sickness and correlated with antibody levels measured by enzyme-linked immunosorbent assay (ELISA). Each of these tests in serum gave a 30% false negative result, but when both were used this fell to 12%. Measurements of IgM in CSF were raised in 87% of patients with advanced disease and in none of the early cases. The IgM levels fell slowly to normal by 12 months after treatment. A high level at this time, or a rise after treatment, was helpful in diagnosing relapsed patients. Antibody levels in CSF were of no use in diagnosis or prognosis, and were raised in many controls.

Enzyme immunoassays for viral diseases.

Microplate enzyme-linked immunosorbent assays (ELISA) for viral diseases were investigated with special reference to rubella. Standardization of the carrier plates, antigens, conjugates, and substrate was found to be essential. The ELISA results were compared with results of hemagglutination-inhibition tests for rubella, and ELISA was used in an epidemiologic study. Antibodies to cytomegalovirus, measles, adenovirus, coxsackieviruses, and herpesviruses were also assayed by ELISA. ELISA has veterinary applications in detection of respiratory syncytial virus and Newcastle disease virus, and it has been used for assay of plant viruses.

Diagnosis of invasive candidosis by enzyme immunoassay of serum antigen.

Enzyme immunoassay was used to measure Candida albicans-related antigen in sera of rabbits and mice infected with C albicans. A range of heterologous antigens tested gave no cross reactions. Of the three patients who were investigated and gave positive reactions, two were confirmed as having deep candida infections. Enzyme immunoassay is efficient, simple, and sensitive, and may prove valuable in the early diagnosis of invasive candida infections.