RESUMO
Aotus monkeys are good models for erythrocyte-induced Plasmodium falciparum and P. vivax infections and have been extensively used in malarial drug and vaccine development. Recently, it has been shown that certain species of Aotus can be infected with sporozoites, and that the degree of susceptibility varies among species. We demonstrate here that Panamanian Aotus lemurinus lemurinus are susceptible to a sporozoite-induced infection, opening the possibility that this species of Aotus could be used as models for testing the efficacy of pre-erythrocytic P. falciparum vaccines and drug candidates directed at the pre-erythrocytic stages of P. falciparum and P. vivax malaria. In this species, we compared sporozoite infection rates. Two of four animals splenectomized prior to infection with sporozoites developed patent parasitemias. Seven of eight animals splenectomized either 7 or 35 days after infection became parasitemic. Additionally, we used a P. falciparum-specific polymerase chain reaction (PCR) method to detect the early appearance of parasitized erythrocytes in the blood prior to detection by conventional microscopy, and found that the parasitemia was detected first in five animals by the PCR method, first in three animals by blood film, with one parasitemia detected simultaneously. We also demonstrated the feasibility of infecting monkeys located in Panama with sporozoites isolated at an insectary in Atlanta, thus documenting the feasibility of similar studies where the insectary and monkey colony are not in the same location. A subsequent attempt to infect these monkeys using sporozoites was not successful, suggesting that this model of human malaria is not yet ready for routine use in vaccine or drug efficacy screening. This model merits further study because of the importance of testing pre-erythrocytic P. falciparum malaria vaccines and drugs in animals.
Assuntos
Aotus trivirgatus/imunologia , Modelos Animais de Doenças , Malária Falciparum/veterinária , Plasmodium falciparum/patogenicidade , Animais , Anopheles/parasitologia , DNA de Protozoário/química , Ensaio de Imunoadsorção Enzimática/veterinária , Feminino , Malária Falciparum/imunologia , Masculino , Hibridização de Ácido Nucleico , Panamá , Parasitemia/sangue , Reação em Cadeia da Polimerase/veterinária , Esplenectomia/veterináriaRESUMO
Infections with the Salvador II strain of Plasmodium vivax in Aotus lemurinus griseimambra monkeys were fed upon by Anopheles freeborni mosquitoes. Periods of mosquito infectivity were determined to establish a model system for the testing of transmission-blocking vaccines. The highest levels of mosquito infection were associated with the ascending asexual parasitemia after reaching 1,000/microl, and before the peak asexual parasite count. Sporozoite-induced infections were more infectious than were trophozoite-induced infections. Secondary episodes of parasitemia were also infectious, indicating the lack of development of naturally developing transmission-blocking immunity to this strain of P. vivax in splenectomized Aotus monkeys following single infections.
Assuntos
Anopheles/parasitologia , Aotidae/parasitologia , Modelos Animais de Doenças , Insetos Vetores/parasitologia , Malária Vivax/parasitologia , Parasitemia/parasitologia , Plasmodium vivax/classificação , Animais , El Salvador , Malária Vivax/prevenção & controle , Malária Vivax/transmissão , Parasitemia/prevenção & controle , Parasitemia/transmissão , Plasmodium vivax/crescimento & desenvolvimento , Plasmodium vivax/imunologia , Vacinas Protozoárias , Estudos Retrospectivos , Esplenectomia , Fatores de TempoRESUMO
A nonimmune American acquired an infection of Plasmodium vivax Type 1 malaria in Brazil in 1994. After returning to the U.S.A., he had a primary attack followed by 3 relapses. The primary attack and first 2 relapses were treated with a standard regimen of chloroquine, followed by 14 days of primaquine (15 mg/day). Following the third relapse, the primaquine treatment was extended to 28 days. No further relapses occurred. The lack of response to primaquine by this strain may recommend it as a suitable candidate for chemotherapeutic study if it can be adapted to an animal model. Anopheles quadrimaculatus mosquitoes infected by feeding on the patient during the first relapse were used to establish the strain in Aotus and Saimiri monkeys. Monkeys supported well the development of long-lasting parasitemia. Anopheles freeborni, Anopheles stephensi, and Anopheles gambiae mosquitoes were readily infected by feeding on the monkeys and by membrane feeding on diluted blood. Monkey-to-monkey transmission was obtained via the bites of infected mosquitoes and the intravenous injection of sporozoites dissected from salivary glands. This parasite is designated as the Brazil I/CDC strain of P. vivax.
Assuntos
Antimaláricos/farmacologia , Aotidae/parasitologia , Malária Vivax/parasitologia , Plasmodium vivax/efeitos dos fármacos , Primaquina/farmacologia , Saimiri/parasitologia , Animais , Anopheles , Antimaláricos/uso terapêutico , Brasil , Cloroquina/farmacologia , Cloroquina/uso terapêutico , Modelos Animais de Doenças , Resistência a Medicamentos , Quimioterapia Combinada , Feminino , Humanos , Insetos Vetores , Malária Vivax/tratamento farmacológico , Malária Vivax/transmissão , Masculino , Parasitemia/tratamento farmacológico , Parasitemia/patologia , Parasitemia/transmissão , Primaquina/uso terapêutico , RecidivaRESUMO
The Santa Lucia strain of Plasmodium falciparum and the Aotus lemurinus griseimembra monkey are proposed as models for the testing of sporozoite vaccines and transmission-blocking vaccines. Approximately 85% of splenectomized monkeys were infected when fed upon by 10 or more heavily infected Anopheles freeborni mosquitoes. Sporozoite-induced infections in monkeys with or without previous infection with P. vivax readily infected mosquitoes, thus making them candidates for testing transmission-blocking vaccines.
Assuntos
Aotus trivirgatus/parasitologia , Modelos Animais de Doenças , Vacinas Antimaláricas , Malária Falciparum/prevenção & controle , Plasmodium falciparum/imunologia , Animais , Anopheles/parasitologia , Pré-Escolar , El Salvador , Feminino , Humanos , Insetos Vetores/parasitologia , Malária Falciparum/parasitologia , Malária Falciparum/transmissão , Parasitemia/parasitologia , Parasitemia/prevenção & controle , Parasitemia/transmissão , Plasmodium falciparum/crescimento & desenvolvimento , EsplenectomiaRESUMO
The Santa Lucia strain of Plasmodium falciparum and the Aotus vociferans monkey were studied as models for the testing of transmission-blocking vaccines. Virulence developed early in the passage history. Despite the use of only small quantities of chlorguanide and/or quinine to control infection coupled with the use of small inocula and delays in splenectomy, mosquito infection was markedly reduced from that seen during primary passage to this species of Aotus. It appears that the model may be most useful during its initial passage from the primary species, Aotus lemurinus griseimembra.
Assuntos
Aotidae , Modelos Animais de Doenças , Vacinas Antimaláricas , Malária Falciparum/prevenção & controle , Plasmodium falciparum/imunologia , Animais , Anopheles/parasitologia , Antimaláricos/uso terapêutico , Pré-Escolar , Feminino , Humanos , Insetos Vetores/parasitologia , Malária Falciparum/tratamento farmacológico , Malária Falciparum/transmissão , Parasitemia/tratamento farmacológico , Parasitemia/prevenção & controle , Parasitemia/transmissão , Plasmodium falciparum/isolamento & purificação , Plasmodium falciparum/patogenicidade , Proguanil/uso terapêutico , Quinina/uso terapêutico , Inoculações Seriadas , Esplenectomia , VirulênciaRESUMO
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.
Assuntos
Antígenos de Protozoários/imunologia , Membrana Eritrocítica/imunologia , Eritrócitos/parasitologia , Plasmodium falciparum/imunologia , Plasmodium/imunologia , Proteínas de Protozoários/imunologia , Animais , Anticorpos Antiprotozoários/análise , Antígenos de Superfície/imunologia , Reações Cruzadas/imunologia , Membrana Eritrocítica/parasitologia , Técnica Indireta de Fluorescência para Anticorpo , Humanos , Malária/imunologia , Malária/veterinária , Malária Falciparum/imunologia , Doenças dos Macacos/imunologia , Plasmodium/classificação , Plasmodium falciparum/classificação , Plasmodium malariae/classificação , Plasmodium malariae/imunologia , SaimiriRESUMO
Sera collected from 164 individuals who had clinical Plasmodium falciparum malaria and came from several areas of Brazil where malaria is endemic were tested for the presence of anti-gametocyte antibodies. Antibodies directed against P. falciparum gametocytes were detected, by IFAT, in the sera of 67.1% of these patients. The prevalence of these antibodies was significantly higher in patients who had undergone multiple attacks of malaria than in those who were experiencing their first attack at the time of serum collection. Although circulating gametocytes were detected in 22% of the patients at this time, there was no difference in the percentages of IFAT positivity between apparent gametocyte 'carriers' and 'non-carriers'. All sera were also tested by ELISA, using a dimer of the nonamer peptide [PEE(L/V)VEEV(I/V)]2, which represents a tandem consensus repeat of the P. falciparum gametocyte antigen, Pfs2400, a target of transmission-blocking antibodies. ELISA demonstrated that 32.9% of the patients had antibodies that reacted with this peptide. Positive ELISA reactions were significantly more frequent amongst the sera of patients who had had multiple malaria attacks than in those undergoing their first malaria episode; positivity was lower in the gametocyte 'carriers' than in their 'non-carriers'. These results demonstrate that anti-gametocyte antibodies, which have already been shown to have potential transmission-blocking activity, are naturally elicited in Brazilian patients, the highest rates of seropositivity occurring after multiple malaria attacks.
Assuntos
Anticorpos Antiprotozoários/sangue , Antígenos de Protozoários/imunologia , Malária Falciparum/imunologia , Proteínas de Protozoários/imunologia , Adolescente , Adulto , Idoso , Antígenos de Protozoários/sangue , Brasil , Ensaio de Imunoadsorção Enzimática , Técnica Indireta de Fluorescência para Anticorpo , Humanos , Pessoa de Meia-Idade , Proteínas de Protozoários/sangue , RecidivaRESUMO
Different species of Saimiri and Aotus monkeys were inoculated with sporozoites of the Salvador I strain of Plasmodium vivax. Of 58 Saimiri inoculated, 45 developed parasitemia (4 following bites and 41 following intravenous inoculation). Prepatent periods ranged from 10 to 63 days. Twelve of 19 monkeys inoculated with sporozoites that had been stored frozen developed patent parasitemia after 16-53 days. Of 41 Aotus monkeys inoculated, only 10 (2 via bites and 8 via intravenous inoculation) developed parasitemia. One of 7 Aotus inoculated with sporozoites that had been frozen developed parasitemia with a prepatent period of 26 days. Mosquitoes were infected by feeding on gametocytes from Aotus and Saimiri monkeys, chimpanzees, and a human. Sporozoites from Anopheles stephensi, Anopheles freeborni, Anopheles dirus, and Anopheles gambiae induced infection.
Assuntos
Malária Vivax/transmissão , Animais , Anopheles/parasitologia , Aotus trivirgatus , Criopreservação , Modelos Animais de Doenças , El Salvador , Humanos , Insetos Vetores/parasitologia , Malária Vivax/sangue , Plasmodium vivax/crescimento & desenvolvimento , Plasmodium vivax/fisiologia , SaimiriRESUMO
We have characterized the circumsporozoite (CS) gene sequences of Plasmodium malariae China-1 CDC, isolated recently from a person who was infected 50 years ago in China, and P. vivax Chesson, isolated 48 years ago from a patient who had returned from New Guinea. These protein sequences were compared with the CS protein sequences of recently isolated P. vivax and P. malariae parasites. In a similar manner, we compared the previously characterized CS protein gene of P. falciparum clone 7G8, derived from a Brazilian isolate collected in 1980, with the CS protein genes of recent P. falciparum field isolates. In the case of the P. malariae CS protein gene, with the exception of an additional copy of major (NAAG) and minor (NDAG) repeat sequences and the presence of one copy of NDEG sequence, the China-1 CDC P. malariae parasite is similar to the Uganda-1 CDC isolate of 1982. In the nonrepeat region, changes were noted in two amino acid residues, one of which is also seen in a closely related monkey malaria parasite, P. brasilianum. In the case of P. vivax CS proteins, the nonrepeat region of the protein in Chesson strain shares identity with nearly 71% of the CS clones characterized from field isolates. In the P. falciparum CS proteins, the 7G8 CS protein sequence is identical to 75% of the genes of recent field isolates in the Th1R-N1 region. In the Th2R and Th3R regions, 34% and 55% of the CS clones analyzed, respectively, had changes at two amino acid residues.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Plasmodium malariae/genética , Plasmodium vivax/genética , Polimorfismo Genético , Proteínas de Protozoários/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Brasil , Clonagem Molecular , Primers do DNA/química , Gâmbia , Variação Genética , Humanos , Dados de Sequência Molecular , Papua Nova Guiné , Plasmodium malariae/química , Plasmodium vivax/química , Proteínas de Protozoários/química , Sequências Repetitivas de Ácido Nucleico , Estudos RetrospectivosRESUMO
Susceptibility to infection of 2 strains of Anopheles gambiae s.s., An. freeborni and An. stephensi, was determined for 2 closely related malaria parasites, Plasmodium malariae and P. brasilianum. Neither strain of An. gambiae supported development of oocyst densities as great as the other 2 anopheline mosquitoes. The ZAN strain of An. gambiae s.s. from Zanzibar was more susceptible to infection with the strain of P. malariae from Uganda than the G-3 strain of An. gambiae s.s. from The Gambia. All species and strains of mosquitoes supported complete development to the presence of sporozoites in the salivary glands.
Assuntos
Anopheles/parasitologia , Plasmodium malariae/fisiologia , Plasmodium/fisiologia , Animais , Aotus trivirgatus , Interações Hospedeiro-Parasita , Pan troglodytes , Saimiri , Especificidade da EspécieRESUMO
Passage of malaria-infected blood through a two-layered column composed of acid-washed glass beads and CF 11 cellulose removes white cells from parasitized blood. However, because use of glass beads and CF 11 cellulose requires filtration of infected blood separately through these two resins and the addition of ADP, the procedure is time-consuming and may be inappropriate for use in the field, especially when large numbers of blood samples are to be treated. Our modification of this process yields parasitized cells free of contaminating leukocytes, and because of its operational simplicity, large numbers of blood samples can be processed. Our procedure also compares well with those using expensive commercial Sepacell resins in its ability to separate leukocytes from whole blood. As a test of usefulness in molecular biologic investigations, the parasites obtained from the blood of malaria-infected patients using the modified procedure yield genomic DNA whose single copy gene, the circumsporozoite gene, efficiently amplifies by polymerase chain reaction.
Assuntos
Separação Celular/métodos , Celulose , Cromatografia/métodos , Vidro , Leucócitos , Malária Falciparum/sangue , Malária Vivax/sangue , Microesferas , Plasmodium falciparum/isolamento & purificação , Plasmodium vivax/isolamento & purificação , Difosfato de Adenosina/farmacologia , Adsorção , Animais , Sequência de Bases , Separação Celular/instrumentação , DNA de Protozoário/genética , DNA de Protozoário/isolamento & purificação , Filtração , Genes de Protozoários , Humanos , Leucócitos/parasitologia , Malária Falciparum/parasitologia , Malária Vivax/parasitologia , Dados de Sequência Molecular , Plasmodium falciparum/genética , Plasmodium vivax/genética , Ativação Plaquetária , Proteínas de Protozoários/genéticaRESUMO
Impaired renal function was observed in sixteen Aotus nancymai 25 and 3 months following infection with the Uganda Palo Alto strain of Plasmodium falciparum. Decrease were noted in the clearance of endogenous creatinine, creatinine excretion, and urine volume while increases were observed in serum urea nitrogen, urine protein, urine potassium, fractional excretion of phosphorus and potassium, and activities of urinary enzymes. The results were suggestive of glomerulonephropathy and chronic renal disease.
Assuntos
Aotus trivirgatus/parasitologia , Rim/fisiopatologia , Malária Falciparum/fisiopatologia , Animais , Sangue/parasitologia , Creatinina/metabolismo , Eletrólitos/metabolismo , Enzimas/urina , Feminino , Taxa de Filtração Glomerular , Glomerulonefrite Membranoproliferativa/etiologia , Glomerulonefrite Membranoproliferativa/urina , Testes de Função Renal , Malária Falciparum/complicações , Malária Falciparum/metabolismo , Malária Falciparum/parasitologia , Masculino , Nitrogênio/metabolismo , Proteinúria/etiologia , Proteinúria/urinaRESUMO
Although several animal models for human cerebral malaria have been proposed in the past, none have shown pathological findings that are similar to those seen in humans. In order to develop an animal model for human cerebral malaria, we studied the pathology of brains of Plasmodium coatneyi (primate malaria parasite)-infected rhesus monkeys. Our study demonstrated parasitized erythrocyte (PRBC) sequestration and cytoadherence of knobs on PRBC to endothelial cells in cerebral microvessels of these monkeys. This is similar to the findings seen in human cerebral malaria. Cerebral microvessels with sequestered PRBC were shown by immunohistochemistry to possess CD36, TSP and ICAM-1. These proteins were not evident in cerebral microvessels of uninfected control monkeys. Our study indicates, for the first time, that rhesus monkeys infected with P. coatneyi can be used as a primate model to study human cerebral malaria.
Assuntos
Modelos Animais de Doenças , Macaca mulatta/parasitologia , Malária Cerebral , Plasmodium/isolamento & purificação , Animais , Sangue/parasitologia , Encéfalo/irrigação sanguínea , Encéfalo/parasitologia , Química Encefálica , Moléculas de Adesão Celular/análise , Endotélio Vascular/parasitologia , Endotélio Vascular/ultraestrutura , Membrana Eritrocítica/ultraestrutura , Eritrócitos/parasitologia , Humanos , Malária Cerebral/parasitologia , Malária Cerebral/patologia , Malária Falciparum , EsplenectomiaRESUMO
South American Aotus and Saimiri monkeys, which are susceptible to infection with human malarias, have been used to develop models for the testing of human malaria vaccines. Studies indicate that blood-stage and sporozoite vaccines can be tested in these monkeys using appropriate strains of parasites.
Assuntos
Aotus trivirgatus/parasitologia , Vacinas Antimaláricas , Malária Falciparum/prevenção & controle , Malária Vivax/prevenção & controle , Plasmodium falciparum/patogenicidade , Plasmodium vivax/patogenicidade , Saimiri/parasitologia , Animais , Aotus trivirgatus/sangue , Aotus trivirgatus/imunologia , Sangue/parasitologia , Culicidae , Suscetibilidade a Doenças , Estudos de Avaliação como Assunto , Humanos , Mordeduras e Picadas de Insetos , Insetos Vetores , Vacinas Antimaláricas/imunologia , Malária Falciparum/parasitologia , Malária Falciparum/transmissão , Malária Vivax/parasitologia , Malária Vivax/transmissão , Plasmodium falciparum/crescimento & desenvolvimento , Plasmodium falciparum/imunologia , Plasmodium vivax/crescimento & desenvolvimento , Plasmodium vivax/imunologia , Saimiri/sangue , Saimiri/imunologia , Especificidade da Espécie , EsplenectomiaRESUMO
Impaired renal function was observed in sixteen Aotus nancymai 25 and 3 months following infection with the Uganda Palo Alto strain of Plasmodium falciparum. Decrease were noted in the clearance of endogenous creatinine, creatinine excretion, and urine volume while increases were observed in serum urea nitrogen, urine protein, urine potassium, fractional excretion of phosphorus and potassium, and activities of urinary enzymes. The results were suggestive of glomerulonephropathy and chronic renal disease
Assuntos
Animais , Cebidae , Rim/patologia , Plasmodium falciparumRESUMO
The new-world monkeys Saimiri sciureus (squirrel monkeys) are currently used as a model to test the efficacy of vaccines against human malaria. To improve our knowledge on this model, we tested the susceptibility of S. sciureus B cells to Epstein-Barr virus (EBV) infection. B-lymphoblastoid cell lines were obtained from six of six healthy animals after infection with the B95-8 source of EBV. The frequency distributions of spleen B cells clonally committed to the production of immunoglobulins M and G, as measured by limiting dilution analysis, were from 1 in 179 to 1 in 1,085 and from 1 in 45 to 1 in 60, respectively, in three monkeys naturally infected with Plasmodium brasilianum. In the same three animals, the frequency of spleen B cells committed to the production of P. brasilianum-specific antibody ranged from 1 in 2,211 to 1 in 9,099. One B-lymphoblastoid cell line producing anti-P. brasilianum-specific antibody was cloned twice, and the immunoglobulin G produced was purified. This monoclonal antibody recognized a parasite component of 197 kDa and was specific for Plasmodium malariae and P. brasilianum parasites. These data document that squirrel monkey B cells naturally primed by an infectious agent can be efficiently used to produce monospecific antibodies against the infectious agent.
Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Antiprotozoários/imunologia , Linfócitos B/imunologia , Malária/imunologia , Plasmodium/imunologia , Saimiri/imunologia , Animais , Antígenos de Protozoários/química , Antígenos de Protozoários/imunologia , Linfócitos B/microbiologia , Western Blotting , Transformação Celular Viral , Herpesvirus Humano 4 , Imunoglobulina G/biossíntese , Imunoglobulina M/biossíntese , Peso Molecular , Proteínas de Protozoários/química , Proteínas de Protozoários/imunologiaRESUMO
A strain of Plasmodium brasilianum was isolated from a naturally infected Saimiri monkey from Peru and subsequently passaged to 21 splenectomized Saimiri sciureus boliviensis monkeys. Nine of 12 attempts to transmit infection by sporozoite inoculation were successful with prepatent periods ranging from 23 to 41 days. Gametocytes were infective to Anopheles freeborni, Anopheles stephensi, Anopheles dirus, Anopheles maculatus, and Anopheles gambiae mosquitoes. The strain demonstrated a high level of resistance to cure with chloroquine.
Assuntos
Anopheles/parasitologia , Cloroquina/uso terapêutico , Malária/veterinária , Doenças dos Macacos/transmissão , Saimiri/parasitologia , Animais , Malária/tratamento farmacológico , Malária/parasitologia , Malária/transmissão , Mefloquina/uso terapêutico , Doenças dos Macacos/tratamento farmacológico , Doenças dos Macacos/parasitologia , RecidivaRESUMO
We describe here the sequence of the circumsporozoite protein gene of the monkey malaria parasite Plasmodium brasilianum and show that the immunodominant repeat domain is the same as that of the human malaria parasite, Plasmodium malariae. The immunodominant epitope on the surface of sporozoites of a third species of human malaria parasite has, therefore, been identified. This genetic based data and the biological similarities between P. brasilianum and P. malariae support their putative zoonotic/anthroponotic relationship. We also show that an ape malaria parasite, Plasmodium reichenowi, and the human malaria parasite, Plasmodium falciparum, have a similar relationship. The implications of these observations are discussed with respect to vaccine development.
Assuntos
Antígenos de Superfície/genética , Plasmodium/genética , Proteínas de Protozoários , Sequência de Aminoácidos , Animais , Antígenos de Protozoários/genética , Antígenos de Superfície/imunologia , Apicomplexa , Sequência de Bases , DNA Recombinante , Reservatórios de Doenças , Imunofluorescência , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Plasmodium falciparum/genética , Plasmodium malariae/genética , Plasmodium vivax/genéticaRESUMO
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.
Assuntos
Anticorpos Antiprotozoários/biossíntese , Antígenos de Protozoários/imunologia , Antígenos de Superfície/imunologia , Malária/imunologia , Plasmodium falciparum/imunologia , Plasmodium malariae/imunologia , Proteínas de Protozoários , Animais , Reações Cruzadas , Imunofluorescência , Humanos , Técnicas de Imunoadsorção , Peso Molecular , Pan troglodytes , PeruRESUMO
Serum samples from 460 patients with existing or previous Plasmodium infections, high antimalarial antibody titres, and no apparent risk of exposure to human T-lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV) were assayed for HTLV-III/LAV antibody; only 1 sample, from a 21-year-old African woman, was strongly reactive by enzyme-linked immunosorbent assay (ELISA) and positive by western blot. Conversely, no sample from 100 HTLV-III/LAV-positive American homosexual men was strongly reactive for antibodies to the four Plasmodium species that infect human beings by an indirect fluorescent antibody technique, or for antibodies to Plasmodium falciparum by an ELISA technique. Thus, exposure to Plasmodium does not result in HTLV-III/LAV seropositivity, and HTLV-III/LAV antibodies are not strongly cross-reactive with malarial antigens.