Urara Kawazoe

Sequence of the gene encoding an immunodominant microneme protein of Eimeria tenella

A heterodisperse family of antigens, previously detected on sporozoites and merozoites of Eimeria tenella, has been localised to the microneme organelles within the sporozoite. Sequencing of genomic and cDNA clones shows that the gene for this antigen family contains 4 exons separated by 3 short (519, 226 and 156 nucleotides) intervening sequences and that the predicted polypeptide from the longest open reading frame has 4 structural domains. One of these contains 5 copies of the thrombospondin-like motif, previously identified in the partial sequence of the gene, which is conserved in a variety of molecules which have been demonstrated to have adhesive properties. A second domain of the polypeptide has strong similarity to a conserved region that occurs in another group of molecules which have adhesive properties, including the alpha subunits of several integrins, complement factor Bb and a number of extracellular matrix glycoproteins. Overall the antigen resembles the thrombospondin-related anonymous protein identified in the erythrocytic stage of Plasmodium falciparum. The structure of the gene supports a role for this microneme antigen in cell-cell or cell-matrix interactions.

Avian anticoccidial activity of a novel membrane-interactive peptide selected from phage display libraries

In the present work, we describe the discovery of PW2, a novel peptide presenting in vitro activity against Eimeria acervulina and E. tenella sporozoites. PW2 was selected from phage display (Ph.D.) peptide libraries by an alternative method of panning using living purified E. acervulina sporozoites as targets. Our results showed that the peptide disrupts the sporozoite pellicle, resembling the effect caused by most natural antimicrobial peptides. PW2 peptide was also effective against fungi and showed low activity against Toxoplasma gondii tachyzoites, but no activity against Trypanosoma cruzi, Crithidia fasciculata epimastigotes, and bacteria. Additionally, the parasiticidal concentrations of PW2 produced a very low lytic effect on mammalian and avian cells. The effectiveness against Eimeria sporozoites and the absence of adverse effects to host cells indicates that PW2 may be used as a model to generate new drugs for the control of avian coccidiosis.

Schistosomiasis mansoni in the municipality of Pedro de Toledo (São Paulo, Brazil) where the Biomphalaria tenagophila is the snail host: I - Prevalence in human population (

Due to the scarce information about the epidemiological features of schistosomiasis in which the vector is Biomphalaria tenagophila, an investigation was carried in Pedro de Toledo in 1980 where such peculiarity is observed. Stool examinations (Kato-Katz method) were performed in 4,741 individuals (22.8% positive to Schistosoma mansoni eggs) of this 583 had previously received chemotherapy and 4,158 remainders, untreated. The schistosomiasis prevalence in those two groups where respectively 31.7% and 21.6%. Epidemiological investigation showed that 83.6% were autochthonous cases from the studied area: the autochthonous prevalence rate, and the intensity of infection in the untreated autochthonous cases were higher in males than in females; the intensity in the latter untreated group was low, 58.5 eggs/g feces (geometric mean). Moreover, according to the age groups the intensity of infections correlated well (rs = 0.745) with the prevalence rates. Schistosomiasis was verified to occur mostly during the leisure time and by the use of water streams for housework in rural zone. Only 0.4% out of 1,137 snails was positive for S. mansoni cercariae, apparently unchanged from the 1978 study when the human prevalence was 12.0%. The studied area presented differences and similarities in relation to the other Brazilian areas were the main intermediate host is B. glabrata.

Resistance to diclazuril in field isolates of Eimeria species obtained from commercial broiler flocks in Brazil

The efficacy of the anticoccidial drug diclazuril against field isolates of Eimeria spp. collected from broiler farms in four different sites of the South and Southeastern regions of Brazil were investigated. The effect of the drug was measured by an assessment of weight gain, lesion score and oocyst production. Two reference laboratory strains not previously exposed to diclazuril were sensitive to the drug. Two field isolates were judged to be sensitive to diclazuril, four were partly resistant and six were resistant to the drug. The response of the isolates to diclazuril varied depending upon the extent of exposure and type of drug programme in use at the farms.

Prevalence of porcine neonatal isosporosis in Brazil

The prevalence of Isospora suis and clinical signs of isosporosis were observed in 33 swine farms from 20 sites in the southeastern state of São Paulo, Brazil. The study was performed by collecting 177 faecal samples from nursing and weaned piglets. A history of clinical neonatal isosporosis, as well as the type of farrowing and nursery houses and the pig management in the farms were correlated to the prevalence of I. suis oocysts. Six faecal samples were collected in each of the farms (two from groups of 10- to 19-day-old piglets, two from groups of 20- to 29-day-old and another two from groups of 30- to 50-day-old pigs). Faecal consistency was also registered at the time of their collection. Chi-square tests were used for statistical analysis. Oocysts were more prevalent in farms with a history of neonatal isosporosis than in those without previous cases. Faecal consistency was not related to oocyst elimination. In farms with a history of clinical isosporosis, faecal samples from groups of 10- to 19-day-old piglets showed a higher prevalence of oocysts than the groups of other ages studied. There was no difference in the prevalence of oocysts between nursing and weaned piglets. Oocysts were more prevalent in faecal samples collected from dirty-cemented floors than from self-cleaning floors in the farrowing houses. Types of floor and pig management in nursery houses were not associated with the presence of oocysts in weaned pigs.

Volutin Granules of Eimeria Parasites are Acidic Compartments and Have Physiological and Structural Characteristics Similar to Acidocalcisomes

The structural organization of parasites has been the subject of investigation by many groups and has lead to the identification of structures and metabolic pathways that may represent targets for anti‐parasitic drugs. A specific group of organelles named acidocalcisomes has been identified in a number of organisms, including the apicomplexan parasites such as Toxoplasma and Plasmodium, where they have been shown to be involved in cation homeostasis, polyphosphate metabolism, and osmoregulation. Their structural counterparts in the apicomplexan parasite Eimeria have not been fully characterized. In this work, the ultrastructural and chemical properties of acidocalcisomes in Eimeria were characterized. Electron microscopy analysis of Eimeria parasites showed the dense organelles called volutin granules similar to acidocalcisomes. Immunolocalization of the vacuolar proton pyrophosphatase, considered as a marker for acidocalcisomes, showed labeling in vesicles of size and distribution similar to the dense organelles seen by electron microscopy. Spectrophotometric measurements of the kinetics of proton uptake showed a vacuolar proton pyrophosphatase activity. X‐ray mapping revealed significant amounts of Na, Mg, P, K, Ca, and Zn in their matrix. The results suggest that volutin granules of Eimeria parasites are acidic, dense organelles, and possess structural and chemical properties analogous to those of other acidocalcisomes, suggesting a similar functional role in these parasites.

The epidemiology and control of schistosomiasis mansoni where Biomphalaria tenagophila is the snail host

Desde 1980, esta-se estudando a epidemiologia e o controle da esquistossomose mansonica no Municipio de Pedro de Toledo (Estado de Sao Paulo, Brasil). Em 1980 a prevalencia avaliada por exame de fezes (metodo de Kato-Katz) foi de 22,8%. Estatisticamente, ao nivel de 5%, nao houve diferenca nas prevalencias observadas nas zonas rural e urbana. A intensidade de infeccao foi baixa (media geometrica de 58,5 ovos por grama de fezes). As maiores prevalencias e intensidades de infeccao foram registradas na faixa etaria de 5 a 29 anos. Geralmente a transmissao da endemia verificou-se durante o lazer. Apenas 0,4% de B. tenagophila mostraram-se positivos para cercarias de S. mansoni. A maioria dos portadores era assintomatico. O programa de controle foi intensificado apos avaliacao dos dados de 1980, resultando em diminuicao acentuada da prevalencia de 22,8% em 1980 para 6%. Esta prevalencia residual vem se mantendo ate 1987. Agora iniciamos estudos para investigar as possiveis causas dessa prevalencia residual.

Importância epidemiológica de alguns animais silvestres na esquistossomose mansônica

The importance of some wild rodents as possible reservoir hosts of S. mansoni related to the epidemiologic chain of this parasite and some biological aspects of these rodents were studied in semi-natural habitats. The experiment was performed in an enclosed area of about 1,000 m2 situated in Taubate, State of S. Paulo, one of the endemic area of human schistosomiasis, during a period of three years and six months (from August 1973 to December 1976). Wild rodents of the following species were used as definitive hosts: Holochilus brasiliensis leucogaster, Zygodontomys lasiurus, Oryzomys nigripes eliurus and Cavia aperea aperea. Biomphalaria tenagophila and B. glabrata were used as intermediate hosts. From August 1973 to January 1976 it was not possible to find any B. tenagophila eliminating S. mansoni cercariae nor any rodents infected with the same parasite. In August, 1975, egg patches of B. glabrata snails were accidentaly introduced into the area and in 1976 some adult snails were eliminating S. mansoni cercariae. In that same year, two Holochilus that were born in the area were discharging S. mansoni eggs in their feces. Some biological data were collected from 41 H. b. leucogaster of which 28 individuals were introduced into and 14 were born in the area. The majority of body weights of rodents born in the area and captured for the first time was between 20 and 50 grams. In this group of 41 rodents observed, body weight continued to increase throughout the life span of each individual sampled. Z. lasiurus and C. a. aperea did not show any infection with S. mansoni and they did not leave any progeny in the area. O. n. eliurus reproduced in the area and remaining there for about 100 days did not show any infection with the parasite. Thus, H. b. leucogaster and B. tenagophila, in the absence of infected humans, will hardly maintain the life cicle of schistosomiasis but Holochilus together with B. glabrata would probably maintain the life cicle of S. mansoni in nature without the presence of infected man, since in the area there is a suitable strain of S. mansoni, both for definitive and intermediate hosts.Com o intuito de averiguar a importância de alguns roedores como possiveis reservatorios do S. mansoni, na ausencia do homem parasitado, foi realizada pesquisa, visando contribuir para o esclarecimento de aspectos ligados a cadeia epidemiologica da esquistossomose, bem como conhecer alguns parâmetros da biologia de certos roedores, em seu habitat semi-natural. O experimento foi realizado num viveiro de 952 m², no municipio de Taubate, Sao Paulo (Brasil), numa area endemica de esquistossomose mansonica humana, e teve a duracao de tres anos e seis meses (agosto de 1973 a dezembro de 1976). Foram utilizados como hospedeiros definitivos, Holochilus brasiliensis leucogaster, Zygodontomys lasiurus, Oryzomys nigripes eliurus e Cavia aperea aperea; como hospeideiro intermediario, Biomphalaria tenagophila e posteriormente B. glabrata. Entre agosto de 1973 e janeiro de 1976, nao houve encontro de B. tenagophila eliminando cercarias de S. mansoni; nao se verificou, tambem, infeccao natural de roedores. Em agosto de 1975, houve introducao acidental de desovas da B. glabrata, cujos adultos, em 1976, apresentaram infeccao por S. mansoni em tres ocasioes, com indices de 2,0; 1,6 e 0,8%. No mesmo ano de 1976, dois Holochilus, nascidos no Viveiro, eliminaram ovos viaveis de S. mansoni. Foi possivel obter dados de 41 H. b. leucogaster, 28 introduzidos e 14 nascidos no local. O exemplar que sobreviveu mais tempo completou 346 dias. Os animais nascidos no Viveiro e capturados pela primeira vez pesavam, em media, 20 a 50 g. Notou-se que o peso corporal aumentou com o tempo e parece nao estacionar ate a morte do animal. Z. lasiurus e C. a aperea nao procriaram e nem adquiriram infeccao ao S. mansoni. O. n. eliurus, procriou e permaneceu vivo, em media, menos de 100 dias; nao foi observada eliminacao de ovos do parasita. E pouco provavel que H. b. leucogaster e B. tenagophila mantenham o ciclo da esquistossomose na ausencia da contaminacao humana, na natureza. Porem, e possivel que, futuramente, H. b. leucogaster na presenca de B. glabrata, possa servir de reservatorio da esquistossomose, na natureza, quando encontrados em abundância e desde que adaptados com cepas adequadas do parasita.

Alguns aspectos da biologia de Biomphalaria glabrata (Say, 1818) e Biomphalaria tenagophila (D'Orbigny, 1835) (Pulmonata, planorbidae): II - Fecundidade e fertilidade

Foi realizada, comparativamente, a avaliacao do numero de capsulas oviferas e ovos por caramujo e do numero de ovos por desova (fecundidade) e a verificacao da taxa de eclosao e de ovos ferteis (fertilidade) de Biomphalaria glabrata e Biomphalaria tenagophila, no periodo de um ano, em condicoes de laboratorio. Verificou-se que a media do numero de ovos por desova foi significativamente maior em B. glabrata (19,9) do que em B. tenagophila (16,2), constatando-se que ambas as especies apresentavam maior fecundidade no mes de abril, embora os fatores ambientes tenham influido pouco no parâmetro em questao. A fecundidade traduzida pelo numero de desovas por caramujo-dia, mostrou-se maior em B. glabrata (0,65) do que em B. tenagophila (0,56), o mesmo acontecendo em relacao ao numero de ovos por caramujo-dia pois B. glabrata apresentou media de 13,4 e B. tenagophila media de 9,9. Considerando-se a fertilidade como a percentagem de eclosao dos caramujos, B. glabrata apresentou media de 95,8% e B. tenagophila a media de 90,5% de eclosao, sendo esta diferenca significativa ao nivel de 5%. As taxas mais elevadas de eclosao em B. glabrata foram verificadas nos meses de nomais elevadas de eclosao em B. glabrata foram verificadas nos meses de novembro a janeiro (98,0%) e em B. tenagophila nos meses outubro-novembro (95,0%) embora nao tenham sido observados ritmo sazonal nem influencia da temperatura na eclosao dos planorbideos estudados.

Competição biológica entre Biomphalaria glabrata (Say, 1818) e Biomphalaria tenagophila (d'Orbigny, 1835) em criadouros naturais no município de Ourinhos, SP (Brasil)

Foram feitas observacoes sobre a provavel competicao entre Biomphalaria tenagophila e Biomphalaria glabrata, em tres criadouros do tipo vala, situados no Municipio de Ourinhos (SP), durante o periodo de 27-11-73 a 20-02-79. As coletas foram realizadas trimestralmente ate dezembro de 1976 e de 1977 a 1979, semestralmente, num total de 17 capturas. Foram coletados 5.249 exemplares de B. tenagophila e 353 de B. glabrata no criadouro 1; no criadouro 2 o total de exemplares foi de 1.703 e 64 para B. tenagophila e B. glabrata, respectivamente e no criadouro 3, 1.249 e 4 exemplares de B. tenagophila e E. glabrata, respectivamente. Apenas os dados relativos ao primeiro criadouro forneceram informacoes relacionadas com o deslocamento de B. glabrata e B. tenagophila, sendo que a analise estatistica sugeriu ter havido competicao entre as duas especies estudadas, com tendencia a exclusao de B. glabrata. A substituicao parece ter ocorrido num periodo de pelo menos cinco anos. Apesar de terem sido observadas evidencias de deslocamento competitivo entre as duas especies, nao foi possivel detectar o mecanismo do fenomeno.Possible competition between Biomphalaria glabrata and Biomphalaria tenagophila were observed at three natural breeding sites in Ourinhos (SP) between November 27, 1973 and February 20, 1979. The snails were collected every three months until 1976; after this period they were every six months. A total of B. tenagophila 5,249 snails and 353 B. glabrata were collected at the first study site (irrigation ditch); at the second environment 1,703 B. tenagophila and 64 B. glabrata were collected, in the third environment 1,249 B. tenagophila and 4 B. glabrata were collected. Only the data from the first freshwater environment furnished information relating to the displacement of B. glabrata and B. tenaglophila. Statistical analysis suggested competition between the two species with a tendency for B. glabrata to be excluded. It seems that the displacement took place over a period of at least five years. Although the evidence for competitive displacement between B. glabrata and B. tenagophila is clear, we were not able to determine the exact mechanism for this phenomenon.