The binding of immunoglobulin to carbohydrate epitopes on the surface of Schistosoma mansoni schistosomula was measured with 125I-labelled protein A in sera from 67 Gambian subjects living in a focus of intense S. haematobium transmission. The levels of such antibody differed considerably between subjects and there was significant variation between age groups. The highest mean level, in subjects aged between 8 and 14 years, was significantly greater than that in older subjects. Previous studies have shown that resistance to post-treatment reinfection with S. haematobium is related to age in this focus, and is greatest in those aged 15 or more years. These differing relationships with age suggest that antibodies directed against carbohydrate epitopes on the surface of the schistosomulum do not have a major protective role in man.

Adolescent↗

PubMedDate not supplied

Dissociation of antibody responses during human schistosomiasis and evidence for enhancement of granuloma size by anti-carbohydrate IgM.

Immunoglobulin (Ig) G and IgM antibody levels to soluble egg antigens (SEA), adult worm glycoproteins (AWGP), carbohydrate antigens (CHO) and cationic exchange fraction 6 (CEF6) were measured in serum specimens taken from Brazilian patients with acute, intestinal, hepato-intestinal and hepatosplenic schistosomiasis mansoni. The antibody levels varied among the groups, with the highest anti-egg antigen responses in the acute patients and the highest anti-adult worm responses in patients with chronic disease. The responses to the component parts of the egg antigens were dissociated, with anti-carbohydrate IgG and IgM responses being highest in the acute infection group and anti-CEF6 IgG responses being uniform among the clinical groups. The possibility of a direct role for anti-CHO antibody responses in egg-induced pathology was investigated using the mouse lung model. The anti-carbohydrate monoclonal antibody NIMP/M45 significantly enhanced granuloma formation. Mice given NIMP/M45 produced granulomas larger than those of naive mice or mice given an unrelated monoclonal antibody, and as large as those produced by mice which had been presensitized to egg antigens. The independent regulation of responses to egg antigens may indicate that such responses are minimized to reduce the pathological consequences of infection whilst allowing the development of protective anti-worm responses.

Acute Disease↗

PubMedDate not supplied

Analysis of anti-keyhole limpet haemocyanin antibody in Brazilians supports its use for the diagnosis of acute schistosomiasis mansoni.

Antibody (immunoglobulin (Ig) G) to the haemocyanin of the keyhole limpet (KLH) (Megathura crenulata), which shares a well defined carbohydrate epitope with the surface of schistosomula of Schistosoma mansoni, was determined by enzyme-linked immunosorbent assay (ELISA) in the sera of Brazilians with acute schistosomiasis. Of 53 such individuals tested, 51 had a level of KLH reactivity in excess of the mean +2 standard deviations of that exhibited by chronically infected individuals. This difference in reactivity allowed the acute cases to be readily identified by visual inspection of ELISA plates. The levels of IgG in patients with hepatointestinal and hepatosplenic schistosomiasis, as well as in non-infected, seropositive residents of endemic areas and infected children from endemic areas, were not statistically different from those of intestinal patients. Significant levels of anti-KLH IgG were not detected in patients with leishmaniasis, Chagas disease, ancylostomiasis or ascariasis. The results support the use of KLH as a means of rapidly and easily identifying individuals with acute schistosomiasis.

Adolescent↗

PubMedDate not supplied

The serological differentiation of acute and chronic Schistosoma japonicum infection by ELISA using keyhole limpet haemocyanin as antigen.

Antibodies (immunoglobulin (Ig) G and IgM) that recognize keyhole limpet haemocyanin (KLH), which shares a well defined carbohydrate epitope with the surface of larval schistosomes, were determined by enzyme-linked immunosorbent assay in patients with acute or chronic schistosomiasis japonica. Marked differences in IgG and IgM responses were evident between acute and chronically infected patients at a serum dilution of up to 1:2000. The acute sera had mean (+/- standard deviation) optical density values at 405 nm for IgG and IgM of 0.64 +/- 0.18 and 0.30 +/- 0.19 respectively; the chronic sera had mean readings for IgG and IgM of 0.14 +/- 0.08 and 0.04 +/- 0.03 respectively. Setting the lowest positive limit at 2 standard deviations above the mean value for chronic sera, 41 (98%) of the 42 patients previously diagnosed as having acute schistosomiasis were correctly identified by anti-KLH IgG and 35 (83%) of the 42 patients were correctly identified by anti-KLH IgM detection. Of 17 patients studied longitudinally, IgG optical density values dropped 45% and those of 5 patients fell below the established cut-off level 6 months after treatment. This study supports the use of KLH for rapidly and easily identifying individuals with acute Schistosoma japonicum infection.

Acute Disease↗

PubMedDate not supplied

Antifungal susceptibilities of Cryptococcus neoformans in north-east Thailand.

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AIDS-Related Opportunistic Infections↗

PubMedDate not supplied

Randomly amplified polymorphic DNA (RAPD) and isoenzyme analysis of Trypanosoma rangeli strains.

Sixteen Trypanosoma rangeli strains were compared by isoenzyme and randomly amplified polymorphic DNA (RAPD) analysis. Eight strains were isolated from either Rhodnius prolixus or Homo sapiens from Honduras, Colombia and Venezuela. Another eight strains were isolated from either Panstrongylus megistus or the rodent Echimys dasythrix from the State of Santa Catarina, southern Brazil. All six T. rangeli strains isolated from P. megistus were co-infections with Trypanosoma cruzi, demonstrating an overlap of the sylvatic cycles of these parasites and that the accurate identification of species is of utmost importance. Both isoenzyme and RAPD analysis revealed two distinct groups of T. rangeli strains, one formed by the strains from Santa Catarina and the other, by the strains from Honduras, Colombia and Venezuela. With the five enzymes used, all the strains from Santa Catarina had identical profiles which overlapped with those of the other regions only in the pattern obtained with malic enzyme. Analysis of 138 RAPD bands by means of an unweighted pair group method analysis (UPGMA) phenogram using the Dice similarity coefficient allowed the separation of the two groups based on their divergence at a lower level of similarity than the phenon line. We show that the identification of T. cruzi and T. rangeli in naturally mixed infections is readily achieved by either RAPD or isoenzyme analysis.

Alanine Transaminase↗

PubMedDate not supplied

[Susceptibility to chemotherapeutic agents of Schistosoma mansoni isolates from patients treated with oxamniquine and praziquantel and not cured].

Ten inhabitants of Itaquara, Bahia, Brazil treated with oxamniquine and subsequently praziquantel were not cured. Schistosoma mansoni isolates derived from these patients were studied. Snails were infected with miracidia derived from the feces of these patients and the cercariae produced used to infect albino mice. The animals were then treated with a single oral dose of oxamniquine (25, 50 and 100mg/kg) or praziquantel (100, 200 and 400 mg/kg). The response to chemotherapy was significantly different in some of the isolates although it was not possible to characterize any of them as resistant. In addition, DNA analysis of the isolates by means of "Random Amplified Polymorphic DNA" indicated a low degree of variability as compared with a laboratory strain, LE. Thus, it was not possible to characterize these organisms at a genetic level as a distinct strain.

Adolescent↗

PubMedDate not supplied

[Monitoring AIDS patients for the development of cytomegalovirus (CMV) disease using multiplex PCR].

The human cytomegalovirus is an important pathogen in patients infected with the human immunodeficiency virus (HIV). The CMV viral load seems to be predictor of the development of the CMV disease in these patients. We used a multiplex PCR protocol that also provides quantitative information in those samples from which a single band is amplified and contains fewer viral genomes than those from which both targets are amplified. Monthly blood samples were collected from 270 AIDS patients. From twenty patients, two CMV targets were amplified three or more consecutive times and these patients developed CMV related disease during the study. In contrast, patients who did not result positive for both viral targets, for three or more consecutive times, or who had alternating positive and negative samples during the follow up did not present CMV related disease. The results suggest that the PCR multiplex can be used for the identification of HIV positive patients with higher risk of development of CMV disease.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

DNA polymorphism of schistosomes and their snail hosts.

Analysis of the genomes of schistosomes and one of their intermediate hosts, Biomphalaria glabrata, using Random Amplified Polymorphic DNA (RAPD) demonstrated that intraspecific genetic polymorphism in the parasite is limited but in the snail is highly pronounced. This suggests an important role for the snail in the determination of the epidemiology of the disease. In addition to their intraspecific stability, schistosome derived RAPDs exhibit a high level of interspecific polymorphism and are thus ideal for the construction of phylogenetic trees. For the detection of intraspecific polymorphisms extensive variation in the mitochondrial DNA is being exploited for the development of a PCR based test for Schistosoma mansoni. Gene level polymorphisms are being analyzed by Low Stringency Single Specific Primer PCR.

Animals↗

PubMedDate not supplied

Sequencing and identification of expressed Schistosoma mansoni genes by random selection of cDNA clones from a directional library.

We have initiated a gene discovery program in Schistosoma mansoni based on the technique of Expressed Sequence Tags (ESTs), i.e. partial sequences of cDNAs obtained from single passes in automatic DNA sequences. ESTs can be used to identify genes on the basis of their homology with sequences from other species deposited in DNA or protein databases. Transcripts with sequences without matches in the databases may represent novel parasite-specific genes. This approach has shown to be very efficient and in less than two years a broad range of novel genes has already been ascertained, more than doubling the number of known S. mansoni genes.

Animals↗

PubMedDate not supplied

The schistosome genome project: RNA arbitrarily primed PCR allows the accelerated generation of expressed sequence tags.

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Amino Acid Sequence↗

PubMedDate not supplied

A low stringency polymerase chain reaction approach to the identification of Biomphalaria glabrata and B. tenagophila, intermediate snail hosts of Schistosoma mansoni in Brazil.

The low stringency-polymerase chain reaction (LS-PCR) with a pair of specific primers for the amplification of the 18S rRNA gene was evaluated as a means of differentiating between the two Schistosoma mansoni intermediate host species in Brazil: Biomphalaria glabrata and B. tenagophila. Individual snails obtained from different states of Brazil were used and the amplification patterns obtained showed a high degree of genetic variability in these species. Nevertheless, 4 and 3 clearly defined specific diagnostic bands was observed in individuals from B. glabrata and B. tenagophila respectively. The detection of snail specific diagnostic bands suggests the possibility of reliable species differentiation at the DNA level using LS-PCR.

Animals↗

PubMedDate not supplied

Contrasting genomic variability between clones from field isolates and laboratory populations of Schistosoma mansoni.

The extent of genomic variability of clones of Schistosoma mansoni obtained from field isolates was compared with that of strains that have been laboratory maintained. Analysis was undertaken using randomly amplified polymorphic DNAs (RAPDs) generated with three primers. Phenograms showing the similarity among the clones were constructed. The data showed that while the laboratory strain is highly homogeneous the clones derived from the field populations were highly variable with 43% of RAPDs exhibiting polymorphisms among 23 clones. Clones isolated from the same infected individual were always more closely grouped than clones from different individuals. The data clearly demonstrated that earlier analyses of the genomic variability in S. mansoni have underestimated this phenomenon due to the failure to examine field isolates.

Animals↗

PubMedDate not supplied

Evidentiation of paramyosin (Sm-97) as a modulating antigen on granulomatous hypersensitivity to Schistosoma mansoni eggs.

A Schistosoma mansoni adult worm anionic fraction (PIII) has previously been shown to protect mice against challenge infection and to reduce pulmonary and hepatic granulomatous hypersensitivity. Serum from PIII-immunized rabbit was used to screen a lambda gt11 cDNA library from S. mansoni adult worm in order to identify antigens capable of modulating granulomatous hypersensitivity. We obtained four clones with 400 (Sm-III.11), 900 (Sm-III.16), 1100 (Sm-III.10) and 1300 (Sm-III.12) bp of length. All clone-specific antibodies were able to recognize most of the PIII components. The sequence analysis showed that these clones presented high homology with S. mansoni paramyosin (Sm-97). These findings ascribe a new function to this antigen with an important role in modulation of granulomatous hypersensitivity to S. mansoni eggs.

Animals↗