43 kDa and 66 kDa, two blood stage antigens induce immune response in Plasmodium berghei malaria.

The hunt for an effective vaccine against malaria still continues. Several new target antigens as candidates for vaccine design are being explored and tested for their efficacy. In the present study the sera from mice immunized with 24,000 × g fraction of Plasmodium berghei has been used to identify highly immunogenic blood stage antigens. The protective antibodies present in immune sera were covalently immobilized on CNBr activated sepharose 4B and used for affinity chromatography purification of antigens present in blood stages of P. berghei. Two polypeptides of 66 and 43 kDa molecular weights proved to be highly immunogenic. They exhibited a strong humoral immune response in mice as evident by high titres in ELISA and IFA. Protective immunity by these two antigens was apparent by in vivo and in vitro studies. These two proteins could further be analysed and used as antigens in malaria vaccine design.

Estudo sobre a eventual utilidade de raios gama na profilaxia da malária transmissível por transfusäo de sangue / Study to evaluate the utilization of gamma irradiation in the prophylaxis of transmissible malaria by blood transfusion

O estudo foi realizado com o objetivo de avaliar a eventual utilidade de raios gama na profilaxia da malária transmissísel por transfusäo de sangue, tendo sido, para isso, usados camundongos infectados pelo Plasmodium berghei. Na primeira fase, quando submetemos sangue deles retirado a 2.500 e 5.000 rad, com associaçäo ou näo de metronidazol, näo obtivemos sucesso, já que todos os animais antes sem a parasitose apresentaram parasitemia e morreram após inoculaçäo do sangue irradiado. Porém, ocorreu êxito parcial na segunda fase, ao serem empregados 10.000 e 15.000 rad, porquanto 20 por cento e 40 por cento dos roedores, respectivamente, embora tenham ficado infectados, sobreviveram, com posterior negativaçäo quanto à presença do P. berghei.

Temporary appearance of a circulating granulocyte-macrophage colony-stimulating factor in lethal murine malaria.

Infection of mice with Plasmodium berghei engendered a temporary appearance of granulocyte-macrophage colony-stimulating factor (GM-CSF) in the serum. The peak of GM-CSF levels was detected at day 2 post-infection, and then gradually decreased. On the other hand, the number of committed stem cells for granulocytes and macrophages (CFU-GM) in bone marrow transiently decreased at day 2 post-infection, and then increased and peaked at day 6 post-infection. When the serum of P. berghei-infected mice was fractionated by gel chromatography on Sephacryl S-300, GM-CSF activity was detected as a single peak with an apparent molecular weight of 64 KDa. GM-CSF was entirely adsorbed to concanavalin A-Sepharose 4B affinity chromatography, and was sensitive to pronase digestion, indicating its glycoprotein nature. These results suggest that the circulating GM-CSF would contribute the increase of granulocyte-macrophage hemopoiesis in the early phase of malaria.

Estudo sobre eventual influencia do estimulo para producao de macrofagos, por meio da proteose-peptona, na infeccao experimental de camundongos pelo Plasmodium berghei / Study about eventual influence of macrophage stimulation by means of proteose-peptone in experimental infection caused by Plasmodium berghei in mice

A disponibilidade de modelo experimental, baseado na infeccao de camundongos pelo Plasmodium berghei, permitiu a realizacao do presente estudo, no qual procurou-se verificar possivel diminuicao da parasitemia e consequente alteracao quanto a mortalidade como decorrencia de exacerbacao macrofagica inespecifica, apos estimulo por meio de proteose-peptona a 10 por cento. Os resultados nao demonstraram a cogitada acao sobre os protozoarios, mantendo-se o nivel de parasitemia e a mortalidade proximos ao verificado no grupo de animais infectados, sem participacao do indutor da producao de macrofagos. Assim, pelo menos de acordo com a metodologia empregada, nao ocorreu a contencao da protozoose, sugerida por informacoes registradas em publicacoes anteriores.

Comparative and sequential histopathology of plasmodium chabaudi-infected balb/c mice

1. Rodent experimental models have been useful to study severe malaria but few serial and controlled studies have been conducted. In the presente investigation, we describe the histopathology of lethal and non-lethal rodent malaria induced by Plasmodium berghei and P. chabaudi. P. berghei malaria shows a uniformly lethal course, while P. chabaudi malaria produces a non-lethal acute infection with recovery and periodical recurdescences. Sequential histopathological changes were also characterized in P. chabaudi malaria to determine the evolution of the lesions. 2. P. berghei-infected mice have a more severe organ involvement and lower blood regenerative changes than P. chabaudi-infected mice. Two patterns of organ involvement were observed by cimparing the two infections. The first is related to nonspecific parasitized red blood cell clearance by liver and spleen. The second is related to specific changes due to a specific parasite strain interaction with the host, such as those found in the lungs. 3. Sequential changes in P. chabaudi-infected mice were characterized by perihepatocytic reticulin fiber deposition during the recovery from infection, which faded in subsequent stages. Other organs had a similar regressive evolution, except splenic lymphoid tissue which underwent histological restoration or even hypertrophy after depletion in the acute stage. No brain or heart lesions were observed in either model during the acute and subsequent stages. 4. P. chabaudi infection, whose histopathology is described here for the first time, should be useful as a non-lethal experimental model to study the evolution of histological alterations in malaria

Infradian modulation of liver nucleic acid and lipid content of adult female Lewis/S rats

Infradian modulation with periods of 168 h and 120 h characterizes the RNA, DNA and lipid content of the liver in adult female Lewis/S rats. Multilinear analysis shwos that the fit of an infradian cosine curve with these periods is statistically significant below the 5% level (P = 0.011;P = 0.007 and P = 0.013) and that they account for 19.0, 22.7 and 20.1% of the overall variability, respectively

Protection of athymic (NU/NU) BALB/c mice against Plasmodium berghei by splenocytes from normal (NU/+) BALB/c mice

Camundongos atímicos BALB/c (Nu/Nu) sucumbem entre 7-13 dias após a inoculaçäo (DAI) da cepa NK65 de Plasmodium berghei. Todavia, seus singenêicos heterozigotos (Nu/+) morrem em 7-8 DAI. Camundongos nude (Nu/Nu) reconstituídos com 2x10 esplenócitos de camundongos heterozigotos singenêicos normais näo infectados (Nu/+) 20 dias antes de inoculaçäo a (DBI) do parasita, sucumbem 2 dias antes que os animais controles. Camundongos nude reconstituídos 10 ou 2 DBI, vivem 2-4 dias a mais que os animais controles e alguns deles sobrevivem. Esses achados indicam que a cepa NK65 de P. berghei induz, no mínimo, dois imunofenômenos dependentes de linfócitos T; um supressivo e outro estimulatório. A reconstituiçäo de camundongos nude com células T de camundongos BALB/c (Nu/+) parece reduzir ou "Bypass" a atividade supressora das células T, o qual leva à formaçäo de uma resposta imune protetora por alguns dos camundongos nude