Parasitized erythrocyte membrane antigens of Plasmodium brasilianum: relationships with the ring-infected erythrocyte surface antigen of Plasmodium falciparum.

An antigen, designated here as the parasitized erythrocyte membrane antigen (PEMA), is present in the erythrocyte membrane surrounding all intraerythrocytic stages of Plasmodium brasilianum. An antibody specific for PEMA appeared in 21 (50%) of 42 antisera from Saimiri sciureus monkeys naturally infected with P. brasilianum. Of these 42 sera, nine (21.4%) contained antibody to the ring-infected erythrocyte membrane antigen (RESA); of these nine sera, six did not react with PEMA. Sera of humans infected with P. malariae reacted with PEMA and RESA in a similar pattern; i.e., of 83 antisera, 71 (85.5%) reacted with PEMA and 30 (36%) reacted with RESA. Only one of these latter 30 sera were not reactive with PEMA. Of 167 sera from humans infected with P. falciparum but not P. malariae, 133 (79.6%) reacted with RESA; of these, 43 (25.7% of the total) reacted with PEMA but not RESA. Although PEMA was demonstrated with P. brasilianum and RESA with P. falciparum, neither PEMA or RESA could be demonstrated with P. malariae. Interactions of PEMA and RESA and the corresponding antibodies offer a method whereby the two morphologically similar quartan species, P. malariae and P. brasilianum, can be readily distinguished from each other and may furnish clues to genetic separation of the two and the mechanisms of interaction of quartan malaria and P. falciparum where they are coendemic.

Antibodies to the ring-infected erythrocyte surface antigen of Plasmodium falciparum elicited by infection with Plasmodium malariae.

The ring-infected erythrocyte surface antigen (RESA) of Plasmodium falciparum (RESA-P), found in the membrane of erythrocytes infected with young asexual stages of P. falciparum, is a promising vaccine candidate. Antibodies to RESA-P were inducible by infection with another human malaria species, P. malariae. Of 298 serum samples from inhabitants of three isolated localities in Peru where P. vivax and P. malariae were endemic and P. falciparum had never been reported, 26% had anti-RESA-P antibodies as evidenced by a modified immunofluorescent-antibody assay and confirmed by Western blot (immunoblot) analysis. These seroepidemiologic observations were corroborated by the fact that of six chimpanzees infected with P. malariae, three developed anti-RESA-P antibodies after infection. The modified immunofluorescent-antibody-reactive antibodies, purified by adsorption and elution on monolayers of glutaraldehyde-fixed and air-dried P. falciparum-infected erythrocytes, reacted in an immunofluorescent-antibody assay with both parasite structures and erythrocyte membrane in P. falciparum antigen preparations, but only with parasite structures in P. malariae antigen preparations. This serologic cross-reactivity between P. falciparum and P. malariae is of interest in view of the importance of RESA-P as a vaccine candidate and because the two species are coendemic in many areas.

Estudio de marcadores de Hepatitis B en meretrices registradas en el Hospital Regional Base Docente de Trujillo (Perú) / Study of hepatitis B markers in prostitudes registered in the Hospital Regional Base Docente de Trujillo (Perú)

Se estudió serología para Hepatitis B (HBV) en 70 meretrices concurren al Hospital Regional Base Docente de Trujillo (costa norte del Perú). Se utilizó la técnica de microelisa de fase sólida para marcadores HBs-Ag, HBs-Ab, HBc-Ab y HBe-Ab. La prevalencia total fue de 51.5% siendo el 12.9% portadoras asintomáticas y el 2.9% portadoras con antigenemia "e", el rsto, 38.5% presentan marcador de antecedente pasado convalecientes o inmunes. Estas cifras nos demuestran claramente que la prostitución representa un posible foco importante de transmisión del virus de la Hepatitis B

Study of coinciding foci of malaria and leptospirosis in the Peruvian Amazon area.

A hyperendemic malaria focus, found in 1973 in a secluded valley in South-eastern Peru, was restudied in 1975. Tests for antibodies to Plasmodium and Leptospira were performed on blood serum and blood slides collected at three locations on the Rio Ene and confluent streams and at two locations in the neighbouring highlands. The hyperendemic focus of P. vivax-P. malariae found at Mission Cutivirini in 1973 was confirmed in this study. Another hyperendemic focus of predominantly P. vivax was found at the village of Saoreni. Lesser amounts of malaria were found at other locations. Serology indicated past or present contact with Leptospira of from 50 to 75% of individuals at all locations. The two hyperendemic malaria foci therefore were embedded in a much larger hyperendemic focus of leptospirosis. The value of the indirect immunofluorescence test for malarial antibodies as a sero-epidemiological tool was emphasized by this study.

Immunological survey in high altitude: effect on antibody production and the complement system.

In order to asses the effect of acute exposure to natural high altitude on some immunological mechanisms of mice, the primary response to SRBC was studied by the direct Hemolytic Plaque and Hemagglutination Tests. A control group was studied in Lima, Peru, 150 m. At high altitude (Ticlio, Peru, 4843 m), we found fewer spleen plaque-forming cells (PFC) and the maximal peak of PFC was delayed 1 day, as compared with the response at a lower altitude. Conversely, there was a higher serum concentration of 2-ME sensitive and resistant hemagglutinin antibodies at high altitude and the 19-S (2-ME sensitive) response was predominant during the first days at high altitude while the 7-S response was retarded. These results are interpreted as a stimulating effect of hypoxia on the 19-S antibody production rather than a cellular proliferation as far as the SRBC system is concerned. Serum concentrations of Igs G, M, A and the fraction C'3 of the Complement (B1C/B1A globulin) were determined in normal natives from three cities at different altitude levels: Morococha-Ticlio, 4680 m; La Oroya, 3700 m; and Tarma, 3051 m by the Radial Immunodiffusion Test. The serum concentration of C'3 was correlated with the total hemolytic activity of Complement (C'H50 method) in a group of natives from Morococha. The control group was of normal natives from Lima. No significant differences were found between resum concentration of Igs G, M and A in both groups, but there was a tendency for higher values of IgA at higher altitudes, and most sera in the high altitude group were above the normal IgG values for adults. The resum concentration of C'3 and the hemolytic activity of Complement were wound to be diminished in the high altitude group. These results are interpreted as an inhibitory effect of the altitude on the sequential activation and/or lysing capability rather than a reduction in the C'3 concentration.