Human monoclonal antibodies to Pf 155, a major antigen of malaria parasite Plasmodium falciparum.

Pf 155, a protein of the human malaria parasite Plasmodium falciparum, is strongly immunogenic in humans and is believed to be a prime candidate for the preparation of a vaccine. Human monoclonal antibodies to Pf 155 were obtained by cloning B cells that had been prepared from an immune donor and transformed with Epstein-Barr virus. When examined by indirect immunofluorescence, these antibodies stained the surface of infected erythrocytes, free merozoites, segmented schizonts, and gametocytes.

Anti-Plasmodium falciparum antibodies acquired by residents in a holoendemic area of Liberia during development of clinical immunity.

Sera from 48 children and adolescents (2-15 years of age), residing in a malaria holoendemic area of Liberia were investigated for specificities and isotypes of anti-P. falciparum antibodies. No clear-cut relationship to the development of clinical immunity was found when the overall antibody activities to total parasite antigens were determined by enzyme-linked immunosorbent assay (ELISA).

Pf 155, a candidate for a blood stage vaccine in Plasmodium falciparum malaria.

Pf 155 is a Mr 155,000 P. falciparum antigen, which is deposited in the erythrocyte membrane at merozoite invasion. The antigen is detected by a modified immunofluorescence assay giving staining of the surface of ring stage infected erythrocytes.

Human antibodies to a Mr 155,000 Plasmodium falciparum antigen efficiently inhibit merozoite invasion.

IgG from a donor clinically immune to Plasmodium falciparum malaria strongly inhibited reinvasion in vitro of human erythrocytes by the parasite. When added to monolayers of glutaraldehyde-fixed and air-dried erythrocytes infected with the parasite, this IgG also displayed a characteristic immunofluorescence restricted to the surface of infected erythrocytes. Elution of the IgG adsorbed to such monolayers gave an antibody fraction that was 40 times more efficient in the reinvasion inhibition assay (50% inhibition titer, less than 1 microgram/ml) than the original IgG preparation.

Antibodies in malarial sera to parasite antigens in the membrane of erythrocytes infected with early asexual stages of Plasmodium falciparum.

Monolayers of human erythrocytes (E) infected with Plasmodium falciparum were briefly fixed with 1% glutaraldehyde and air dried. They were then exposed to sera from patients with P. falciparum malaria or from donors immune to this parasite and tested in an indirect immunofluorescence assay (IFA).

Studies on the specificity of anti-erythrocyte antibodies in the serum of patients with malaria.

Sera from patients with Plasmodium falciparum, P. vivax or P. ovale malaria were selected according to their high levels of antibodies against human erythrocyte membranes as measured in a microELISA.

A comparison of knobby (K+) and knobless (K-) parasites from two strains of Plasmodium falciparum.

Erythrocytes infected with Plasmodium falciparum develop knob-like protrusions on their membranes. Knobby (K+) parasites of the FCR-3 (Gambian) strain have been shown to possess a histidine-labelled protein of apparent molecular weight 80 000 which is absent from knobless (K-) variants of the same strain. Here we report similar findings with K+ and K- parasites of another strain, the Malayan Camp strain, and also with cloned K+ and K- parasites of the FCR-3 strain.

Characterization of the humoral immune response in Plasmodium falciparum malaria. II. IgG subclass levels of anti-P. falciparum antibodies in different sera.

The IgG subclass levels of anti-Plasmodium falciparum antibodies in human sera were determined in ELISA with monoclonal mouse antibodies specific for the human IgG subclasses as analytical reagents. The parasite antigen was a trophozoite/schizont enriched preparation of in vitro cultivated P. falciparum.

Characterization of the humoral immune response in Plasmodium falciparum malaria. I. Estimation of antibodies to P. falciparum or human erythrocytes by means of microELISA.

An enzyme linked immunosorbent assay (ELISA) has been developed to estimate disease related antibodies in sera from malaria patients or individuals living in malaria endemic areas. As antigen, Percoll enriched fractions (mainly late trophozoites, schizonts) from Plasmodium falciparum in vitro cultures were used. An ELISA with ghosts from normal human red blood cells (RBC) was performed in parallel.

Monoclonal anti-parasite and anti-RBC antibodies produced by stable EBV-transformed B cell lines from malaria patients.

To produce human monoclonal antibodies associated with infectious disease, peripheral blood lymphocytes (PBL) from patients with Plasmodium falciparum malaria were transformed with EB-virus in vitro. To enrich for malaria-specific B cells, PBL were incubated for 3 days with unsoluble P. falciparum antigen before EBV-transformation.

Intracranial calcifications probably due to congenital Chagas' disease.

A case of congenital Chagas' disease in which intracranial calcifications were observed on examination at the age of 5 months is described.

Asymptomatic congenital Chagas' disease in a 5-year-old child.

A case of asymptomatic Chagas' disease is a 5-year-old boy is described. The boy was born in Romania in 1975 and had never visited an area where Chagas' disease is endemic. It is important bear in mind the possibility of transplacental transmission, in view of increasing number of immigrants and refugees coming from South and Central America.

Firearm residue detection by instrumental neutron activation analysis.

Work leading to an improved technique for firearm discharge residue detection by neutron activation is described. The troublesome and time-consuming postirradiation chemistry has been eliminated; also, sample size has been minimized to accommodate some 130 samples per irradiation capsule. To put the method in a proper perspective, previous work has been referenced and discussed.