Judith K. Kloetzel

Anophelines in the state of Acre, Brazil, infected with Plasmodium falciparum, P. vivax, the variant P. vivax VK247 and P. malariae.

Anophelines collected indoors and in the peri-domiciliary area in 3 localities in the Amazon region, state of Acre, Brazil, from August 1990 to January 1991 were examined by enzyme-linked immunosorbent assay (ELISA) using specific monoclonal antibodies directed against the repeats of the circumsporozoite proteins of Plasmodium falciparum, P. vivax, P. vivax V247, and P. malariae. Of the 3056 specimens collected, 2610 were Anopheles oswaldoi, 362 A. deaneorum, 60 A. triannulatus and 24 were A. darlingi. The infection rates of A. oswaldoi were 3.41% for P. falciparum, 2.26% for P. vivax, 1.22 for P. vivax VK247, and 0.42% for P. malariae. For A. deaneorum, the infection rates were 2.76% for P. falciparum, 0.55% for P. vivax, and 0.82% for P. vivax VK247. All samples of the other 2 species collected (A. triannulatus and A. darlingi) were negative in the ELISA. There were certain differences in the anopheline distribution and infection rates between these localities, and in one only A. oswaldoi was found to be infected. These results strongly point to A. oswaldoi as the main malaria vector in the region. No difference was found between the potential vectors of P. vivax and P. vivax VK247. The significance of these findings for malaria control is discussed.

Influence of male gonadal hormones on the parasitemia and humoral response of male Calomys callosus infected with the Y strain of Trypanosoma cruzi

Abstract Effects of orchiectomy on male Calomys callosus infected with the Y strain of Trypanosoma cruzi were studied. Male C. callosus of the same age and weight were divided into three groups: intact, sham operated, and castrated. After 1 month they were inoculated (i.p.) with 4000 blood trypomastigotes. Parasitemia was lower in orchiectomized animals than in the intact and sham groups. Hormone replacement with decanoate testosterone raised the parasitemia of castrated animals to levels similar to those of their intact and sham counterparts. Antibody levels were monitored by complement-mediated lysis. The trypomastigote lysis percentage varied through the course of infection, according to hormonal status and number of parasites during the acute phase. The most significant differences were found on the 30th day after infection, when lytic antibodies of intact males were high compared to the orchiectomized and sham groups. Higher resistance with lower lysis indexes were observed after orchiectomy, compared to intact and sham males.

Infeccao do Anopheles (Kerteszia) cruzi por Plasmodium vivax e Plasmodium vivax variante VK247 nos Municipios de Sao Vicente e Juquitiba, Sao Paulo

O Estado de Sao Paulo, situado na regiao Sudeste do Brasil, apresenta esporadicamente casos autoctones de malaria que se caracterizam pela presenca de quadro clinico benigno com parasitemias baixas e sintomatologia branda, identificados como malaria vivax. Pouco se sabe a respeito da sintomatologia e resposta imune desenvolvidas pelo ser humano para as variantes Plasmodium vivax VK247 e Plasmodium vivax-like humano. Estas variantes sao transmitidas pelo mosquito Anopheles (Kerteszia) cruzii, uma das especies mais abundantes no Sudeste brasileiro. O objetivo deste trabalho foi verificar a infeccao em anofelinos desta regiao, atraves do teste imunoenzimatico ELISA com utilizacao de anticorpos monoclonais especificos dirigidos contra as regioes repetitivas da proteina circunsporozoita de P. vivax classico, P. brasilianum/P. malariae e P. vivax VK247. Coletas entomologicas foram realizadas no periodo de 1991 a 1993 em Sao Vicente e Juquitiba, municipios localizados em area remanescente da Mata Atlântica do Estado de Sao Paulo. A Mata Atlântica e rica em plantas da familia Bromeliaceae, criadouros de formas imaturas de anofelinos do subgenero Kerteszia. De um total de 1117 especimes de An. (Ker.) cruzii capturados no Municipio de Sao Vicente, 0,179% foram positivos para P. vivax classico. Em Juquitiba, dentre 1161 An. (Ker.) cruzii pesquisados, 0,086% foram positivos para o P. vivax VK247, o que demonstra a presenca da variante na regiao. Embora o indice de infeccao encontrado seja baixo, a alta densidade destes mosquitos e sua voracidade (picam durante as 24 h do dia) poderiam compensar a baixa porcentagem de especimes infectados.

Antibodies anti Bloodstream and Circumsporozoite Antigens (Plasmodium vivax and Plasmodium malariae/P. brasilianum) in Areas of Very Low Malaria Endemicity in Brazil

During 1992-1994, 33 malaria cases were reported in two regions in Brazil where few sporadic atypical cases occur, most of them in home owners, who are weekenders, while home caretakers live there permanently. Indirect Fluorescent Antibody Test (IFAT), with Plasmodium vivax, and Enzime Linked Immunosorbent Assay (ELISA) with repeat peptides of the circumsporozoite (CS) proteins of the 3 known P. vivax variants and P. malarie/P. brasilianum, were performed on 277 sera, obtained within a 5 to 10 km range of malaria cases. Very rarely did any of these donors recall typical malaria episodes. Blood smears of all but 5 were negative. One of the 5 malaria cases included in our serology was of a home owner, I of a permanent resident, 3 from Superintendência de Controle de Endemias employees who went there to capture mosquitoes. In Region 1 the prevalence of IFAT positive sera was 73% and 28% among caretakers, 18% and 9.6% among home owners. In Region 2 (3 localities) no distinction was possible between caretakers and home owners, IFAT positivity being 38%, 28% and 7%. The relative percentage of positive anti-CS repeats ELISA, differed for each of the peptides among localities. Dwellings are in the vicinity of woods, where monkeys are frequently seen. The origin of these malaria cases, geographical differences and high seropositivity is discussed.

Prostaglandin and nitric oxide regulate TNF-α production during Trypanosoma cruzi infection

Abstract The mechanisms that control TNF- α production by macrophages during Trypanosoma cruzi infection are still unknown. Destruction of intracellular forms by cytokine activated macrophages is considered to be a major mechanism of parasite elimination. Although in vitro TNF- α contributes to enhanced parasite destruction by macrophages, previous work in vivo has shown that as the parasite burden increases, serum TNF- α levels decline. In this report we show that TNF- α production by peritoneal adherent cells is elevated at the initial phase of T. cruzi infection. As infection progresses TNF- α production decreases. The observed reduction is partly due to inhibition, largely exerted by endogenous PG and secondarily by NO. Inhibition of their synthesis partially restored the ability to produce high levels of TNF- α to macrophages upon stimulation by LPS. Neither endogenous IL-10 nor TGF- β seem to be involved in the negative regulation of TNF- α production.

Comparative susceptibility of two members of the Anopheles oswaldoi complex, An. oswaldoi and An. konderi, to infection by Plasmodium vivax

We compared the susceptibility of Anopheles oswaldoi and An. konderi to infection by Plasmodium vivax based on the proportion of mosquitoes presenting oocysts and sporozoites. Anophelines were captured in the State of Acre and Rondônia, Brazilian Amazon, and used to obtain F1 progenies. After emergence of adults, male genitalia of mosquitoes of each family were dissected in order to identify them as either An. oswaldoi or An. konderi. F1 progenies of field-captured An. oswaldoi, An. konderi and An. darlingi (used as control) were fed simultaneously on P. vivax-infected blood. Mosquitoes were dissected on day 10-12 after feeding and examined for the presence of oocysts and sporozoites. Both An. oswaldoi and An. konderi developed oocysts in the midguts, however, the percentage of oocyst-positive mosquitoes for An. oswaldoi (13.8%) was higher than for An. konderi (3.3%), and only An. oswaldoi developed salivary infection with sporozoites (6.9% of positivity). Infection rates in An. darlingi ranged from 22.5% to 30.0% for both oocysts and sporozoites. These results indicate that An. oswaldoi can transmit P. vivax and suggest that it is more susceptible than An. konderi. Although An. oswaldoi is an exophilic and zoophilic species, it may be involved in malaria transmission as possibly occurred in the State of Acre.

Macrophage activation and histopathological findings in Calomys callosus and Swiss mice infected with several strains of Trypanosoma cruzi

Peritoneal macrophage activation as measured by H2O2 release and histopathology was compared between Swiss mice and Calomys callosus, a wild rodent, reservoir of Trypanosoma cruzi, during the course of infection with four strains of this parasite. In mice F and Y strain infections result in high parasitemia and mortality while with silvatic strains Costalimai and M226 parasitemia is sub-patent, with very low mortality. H2O2 release peaked at 33.6 and 59 nM/2 x 10(6) cells for strains Y and F, respectively, 48 and 50 nM/2 x 10(6) for strains Costalimai and M226, at different days after infection. Histopathological findings of myositis, myocarditis, necrotizing arteritis and absence of macrophage parasitism were found for strains F and Costalimai. Y strain infection presented moderate myocarditis and myositis, with parasites multiplying within macrophages. In C. callosus all four strains resulted in patent parasitemia which was eventually overcome, with scarce mortality. H2O2 release for strains Y and F was comparable to that of mice-peaks of 27 and 53 nM/2 x 10(6) cells, with lower values for strains Costalimai and M226-16.5 and 4.6 nM/2 x 10(6) cells, respectively. Histopathological lesions with Y and F strain injected animals were comparable to those of mice at the onset of infections; they subsided completely at the later stages with Y strain and partially with F strain infected C. callosus. In Costalimai infected C. callosus practically no histopathological alterations were observed.

Morphological aspects of the myocarditis and myositis in Calomys callosus experimentally infected with Trypanosoma cruzi: fibrogenesis and spontaneous regression of fibrosis

Calomys callosus a wild rodent, is a natural host of Trypanosoma cruzi. Twelve C. callosus were infected with 10(5) trypomastigotes of the F strain (a myotropic strain) of T. cruzi. Parasitemia decreased on the 21st day becoming negative around the 40th day of infection. All animals survived but had positive parasitological tests, until the end of the experiment. The infected animals developed severe inflammation in the myocardium and skeletal muscle. This process was pronounced from the 26th to the 30th day and gradually subsided from the 50th day becoming absent or residual on the 64th day after infection. Collagen was identified by the picro Sirius red method. Fibrogenesis developed early, but regression of fibrosis occurred between the 50th and 64th day. Ultrastructural study disclosed a predominance of macrophages and fibroblasts in the inflammatory infiltrates, with small numbers of lymphocytes. Macrophages had active phagocytosis and showed points of contact with altered muscle cells. Different degrees of matrix expansion were present, with granular and fibrillar deposits and collagen bundles. These alterations subsided by the 64th days. Macrophages seem to be the main immune effector cell in the C. callosus model of infection with T. cruzi. The mechanisms involved in the rapid fibrogenesis and its regression deserve further investigation.

Acquired immunity in mice infected with strains of immunological types A and B of Trypanosoma cruzi

Abstract Groups of 20 mice were inoculated with cultural forms of strains of Trypanosoma cruzi of two distinct immunological types: strains Y and L isolated from humans; M, from a bat (type A); strains 8857 and OPF, from opossums; and 8717, from a wild rat (type B). Parasitemia and mortality rates recorded during 7 weeks showed the human strains to be more infective than the animal strains, the course of parasitemia being, however, quite different when human strains Y and L were compared. A challenge inoculation of blood forms of virulent Y strain was performed in half of the mice previously inoculated with the cultural forms of each strain, the other half being kept as controls. Subsequent observation for 8 weeks revealed that some protection was conferred by all strains, but while no definite differences in mortality rates were verified, the proportion of animals with parasitemia was lower among mice previously infected with cultural forms of the Y (homologous) strain. Protection tests could not distinguish type A and B strains of T. cruzi; this suggests that defense mechanisms do not depend on the antigenic differences responsible for the “ in vitro ” typing of the strains.

Lack of protection against Trypanosoma cruzi by multiple doses of T. lewisi culture forms. A discussion on some strains of "lewisi".

Abstract No protection against Trypanosoma cruzi was afforded to mice by previously inoculating multiple doses of T. lewisi blood stream forms, strain RU or culture forms of the IMT strain. Since these results conflicted with those obtained by other authors, we secured a sample of the strain used by them. This strain, labeled “ T. lewisi ” and which we called “F”, was verified to be actually T. cruzi . It was characterized by its morphologic features in axenic cultures, its capability to infect HeLa cells where the intracellular cycle was completed, by its infectivity for white mice which had amastigotes in their heart muscle, and in which the strain has been maintained by serial passages, and by the completion of its biologic cycle in triatoma bugs. The necessity for carefully testing doubtful strains, and the criteria to be adopted in these cases are discussed.